Putative Methyltransferase Gene Research Articles

Comparative Genomics and Functional Studies of Putative m6A Methyltransferase (METTL) Genes in Cotton.

N6-methyladenosine (m6A) RNA modification plays important regulatory roles in plant development and adapting to the environment, which requires methyltransferases to achieve the methylation process. However, there has been no research regarding m6A RNA methyltransferases in cotton. Here, a systematic analysis of the m6A methyltransferase (METTL) gene family was performed on twelve cotton species, resulting in six METTLs identified in five allotetraploid cottons, respectively, and three to four METTLs in the seven diploid species. Phylogenetic analysis of protein-coding sequences revealed that METTL genes from cottons, Arabidopsis thaliana, and Homo sapiens could be classified into three clades (METTL3, METTL14, and METTL-like clades). Cis-element analysis predicated the possible functions of METTL genes in G. hirsutum. RNA-seq data revealed that GhMETTL14 (GH_A07G0817/GH_D07G0819) and GhMETTL3 (GH_A12G2586/GH_D12G2605) had high expressions in root, stem, leaf, torus, petal, stamen, pistil, and calycle tissues. GhMETTL14 also had the highest expression in 20 and 25 dpa fiber cells, implying a potential role at the cell wall thickening stage. Suppressing GhMETTL3 and GhMETTL14 by VIGS caused growth arrest and even death in G. hirsutum, along with decreased m6A abundance from the leaf tissues of VIGS plants. Overexpression of GhMETTL3 and GhMETTL14 produced distinct differentially expressed genes (DEGs) in A. thaliana, indicating their possible divergent functions after gene duplication. Overall, GhMETTLs play indispensable but divergent roles during the growth of cotton plants, which provides the basis for the systematic investigation of m6A in subsequent studies to improve the agronomic traits in cotton.

Rice Putative Methyltransferase Gene OsPMT16 Is Required for Pistil Development Involving Pectin Modification.

Pectin synthesis and modification are vital for plant development, although the underlying mechanisms are still not well understood. Furthermore, reports on the function of pectin in the pistil are limited. Herein, we report the functional characterization of the OsPMT16 gene, which encodes a putative pectin methyltransferase (PMT) in rice. The cell walls of rice leaves contain less pectin, and chemical analysis of pectin in the flower organ had not been previously performed. Therefore, in the present study, the amount of pectin in the reproductive tissues of rice was investigated. Of the reproductive tissues, the pistil was especially rich in pectin; thus, we focused on the pistil. OsPMT16 expression was confirmed in the pistil, and effects of pectin methylesterification regulation on the reproductive stage were investigated by studying the phenotype of the T-DNA insertion mutant. The ospmt16 mutant showed significantly reduced fertility. When the flowers were observed, tissue morphogenesis was abnormal in the pistil. Immunofluorescence staining by pectin-specific monoclonal antibodies of the pistil revealed that total pectin and esterified pectin were decreased among ospmt16 mutants. These results indicate that OsPMT16 contributes significantly to pistil development during reproductive growth.

Characterization of the Putative Cytosine RNA Methyltransferase TbCRMT5 from Trypanosoma brucei

RNA methylation is a type of posttranscriptional modification that plays an important role in controlling gene expression. The organism Trypanosoma brucei, the protozoan parasite responsible for Human African Trypanosomiasis, does not seem to have abundant promoter regions or transcriptional regulation machinery. Thus, RNA methylation may play an especially important role in regulating gene expression in this organism. Recently, we have identified seven putative cytosine RNA methyltransferase (CRMT) genes in T. brucei. One of the putative CRMTs, termed CRMT5, is required for maximum parasite growth. The purpose of this research is to provide evidence for genuine RNA methyltransferase activity. CRMT5 was expressed in E. coli with an N‐terminal 6x‐histidine tag and purified using a His‐affinity column. Purified CRMT5 was used in a series of methyltransferase assays using luciferase activity as a readout. CRMT5 addition resulted in luciferase activity in the presence of cytosine‐containing RNA (T. brucei total RNA and Poly‐IC RNA). There was little to no luciferase activity observed in the presence of RNA that lacks cytosine or when a mock purification from E. coli without the CRMT5 gene was used. Furthermore, a CRMT5 mutant was created changing a putative active site cysteine to alanine (C439A). We expect the mutant to show reduced luciferase activity in the methyltransferase assay. Future experiments will include performing a methyltransferase reaction with CRMT5 and subsequently isolating the RNA for bisulfite sequencing to confirm the methylation of cytosine bases, performing methyltransferase assays with different substrates to determine if there is a binding preference, and confirming our methyltransferase assay results with a radioactivity assay. Evidence for the presence of 5‐methylcytosine and RNA methyltransferases indicates the presence of a process to create an epitranscriptome in T. brucei.Support or Funding InformationNIH grant 1R15AI133428‐01 to KTM

Identification of RNA Modification Enzymes in Trypanosoma brucei

RNA methylation is a type of posttranscriptional modification that plays an important role in controlling gene expression. The organism Trypanosoma brucei, the protozoan parasite responsible for Human African Trypanosomiasis, does not seem to have abundant promoter regions or transcriptional regulation machinery. Thus, RNA methylation may play an especially important role in regulating gene expression in this organism. We have identified the presence of 5‐methylcytosine in T. brucei RNA using both mass spectrometry and sodium bisulfite sequencing. Recently, we have identified seven putative cytosine RNA methyltransferase (CRMT) genes in T. brucei. All seven CRMTs are expressed in bloodstream and procyclic form parasites, as detected by qRT‐PCR. Two of the putative CRMTs, termed CRMT4 and CRMT5, are required for maximum parasite growth. Although we suspect these genes to be RNA methyltransferases, we do not have evidence for RNA methyltransferase activity. Both CRMT4 and CRMT5 were expressed in E. coli with N‐terminal 6x‐histidine tags. CRMT4 was produced in E. coli but was difficult to purify. SDS‐PAGE results for an N‐terminal His tagged protein indicate CRMT4 insolubility. Our next step will be to use PCR to create smaller fragments of CRMT4, which may be soluble. CRMT5 was produced in E. coli with an N‐terminal His tag and purified using a His‐affinity column. Purified CRMT5 was used in a series of methyltransferase assays using luciferase activity as a readout. CRMT5 addition results in luciferase activity in the presence of cytosine‐containing RNA (T. brucei total RNA and Poly‐IC RNA). There was little to no luciferase activity observed in the presence of RNA that lacks cytosine or when a mock purification from E. coli without the CRMT5 gene was used. Our next step will be to perform a methyltransferase reaction with CRMT5 and subsequently isolate the RNA for bisulfite sequencing to confirm the methylation of cytosine bases. Evidence for the presence of 5‐methylcytosine and RNA methyltransferases indicates the presence of a process to create an epitranscriptome in T. brucei.Support or Funding InformationNIH, 1R15AI133428‐01This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

The SCO1731 methyltransferase modulates actinorhodin production and morphological differentiation of Streptomyces coelicolor A3(2)

Streptomyces coelicolor is a Gram-positive microorganism often used as a model of physiological and morphological differentiation in streptomycetes, prolific producers of secondary metabolites with important biological activities. In the present study, we analysed Streptomyces coelicolor growth and differentiation in the presence of the hypo-methylating agent 5′-aza-2′-deoxycytidine (5-aza-dC) in order to investigate whether cytosine methylation has a role in differentiation. We found that cytosine demethylation caused a delay in spore germination, aerial mycelium development, sporulation, as well as a massive impairment of actinorhodin production. Thus, we searched for putative DNA methyltransferase genes in the genome and constructed a mutant of the SCO1731 gene. The analysis of the SCO1731::Tn5062 mutant strain demonstrated that inactivation of SCO1731 leads to a strong decrease of cytosine methylation and almost to the same phenotype obtained after 5-aza-dC treatment. Altogether, our data demonstrate that cytosine methylation influences morphological differentiation and actinorhodin production in S. coelicolor and expand our knowledge on this model bacterial system.

Identification of a putative methyltransferase gene of Babesia bigemina as a novel molecular biomarker uniquely expressed in parasite tick stages

BackgroundBovine babesiosis is caused by apicomplexan pathogens of the genus Babesia such as B. bigemina and B. bovis. These tick-borne pathogens have a complex life-cycle involving asexual multiplication in vertebrate hosts and sexual reproduction in invertebrate vectors. In the tick midgut, extracellular Babesia parasites transform into gametes that fuse to form zygotes. Understanding the mechanisms that underlie formation of extracellular Babesia tick stages is an important step towards developing control strategies for preventing tick infection and subsequent parasite transmission.ResultsWe induced B. bigemina sexual stages in vitro by exposing parasites to Tris 2-carboxyethyl phosphine (TCEP). Subsequently, we identified a novel putative methyltransferase gene (BBBOND_0204030) that is expressed uniquely in all B. bigemina tick stages but not in blood stages. In vitro TCEP-exposed B. bigemina presented diverse morphology including parasites with long projections, round forms and clusters of round forms indicative of sexual stage induction. We confirmed the development of sexual stages by detecting upregulation of previously defined B. bigemina sexual stage marker genes, ccp2 and 3, and their respective protein expression in TCEP-induced B. bigemina cultures. Next, transcription analysis of in vitro TCEP-induced B. bigemina culture based on an in silico derived list of homologs of Plasmodium falciparum gamete-specific genes demonstrated differential expression of the gene BBBOND_0204030 in induced cells. Further examination of ex vivo infected ticks demonstrated that BBBOND_0204030 is transcribed by multiple stages of B. bigemina during parasite development in tick midgut, ovary and hemolymph. Interestingly, ex vivo results confirmed our in vitro observation that blood stages of B. bigemina do not express BBBOND_0204030 and validated the in vitro system of inducing sexual stages.ConclusionsHerein we describe the identification of a B. bigemina gene transcribed exclusively by parasites infecting ticks using a novel method of inducing B. bigemina sexual stages in vitro. We propose that this gene can be used as a marker for parasite development within the tick vector. Together, these tools will facilitate our understanding of parasite-tick interactions, the identification of novel vaccine targets and, consequently, the development of additional strategies to control bovine babesiosis.

Cloning and Expression Analysis of ZmERD3 Gene From Zea mays.

BackgroundStresses (such as drought, salt, viruses, and others) seriously affect plant productivity. To cope with these threats, plants express a large number of genes, including several members of ERD (early responsive to dehydration) genes to synthesize and assemble adaptive molecules. But, the function of ERD3 gene hasn’t been known so far.ObjectivesThe purpose of the present study was to clone the stress-resistance gene: ZmERD3, and to analyze its expression pattern in the maize plant organs at different stages and under various stress treatments.Materials and MethodsMaizeGDB database search together with the bioinformatics analysis led to the identification of ZmERD3 gene in Zea mays. The cDNA sequence and promoter of ZmERD3 gene were obtained through PCR. Bioinformatics analysis was performed through online tools. The tissue-specific expression profile of the ZmERD3 gene in maize plant was carried out using the quantitative real time PCR (qRT-PCR) technique and its expression pattern in response to stress treatments (such as PEG, NaCl, ABA, and low temperature) was also analyzed through qRT-PCR method.ResultsBased on the homology alignment with AtERD3 (XP_002867953) in MaizeGDB (http://www. maizegdb.org/), the cDNA sequence and promoter region of the ZmERD3 gene were obtained. The bioinformatic analysis showed that ZmERD3 protein has one specific hit of methyltransferase and a high probability of location in the cytoplasm, and there are many cis-regulatory elements responsive to light, heat, cold, dehydration, as well as other stresses in its promoter sequence. Expression analysis revealed that the amount of ZmERD3 mRNA is different in all indicated organs of the maize plant. In addition, the ZmERD3 expression could be induced by abiotic stress treatments. Compared to the control, treatment with NaCl or PEG-6000 could significantly enhance the expression ability of ZmERD3 gene. As well, its expression level was increased about 20 times above the control after exposure to NaCl and PEG-6000 treatments for 3-6 h.ConclusionsOne putative methyltransferase gene, ZmERD3 was cloned. ZmERD3 expression exhibited an obvious tissue-specificity, and its expression could make a significant response to NaCl and PEG-6000 treatments.

The highly heterogeneous methylated genomes and diverse restriction-modification systems of bloom-forming Microcystis

The occurrence of harmful Microcystis blooms is increasing in frequency in a myriad of freshwater ecosystems. Despite considerable research pertaining to the cause and nature of these blooms, the molecular mechanisms behind the cosmopolitan distribution and phenotypic diversity in Microcystis are still unclear. We compared the patterns and extent of DNA methylation in three strains of Microcystis, PCC 7806SL, NIES-2549 and FACHB-1757, using Single Molecule Real-Time (SMRT) sequencing technology. Intact restriction-modification (R-M) systems were identified from the genomes of these strains, and from two previously sequenced strains of Microcystis, NIES-843 and TAIHU98. A large number of methylation motifs and R-M genes were identified in these strains, which differ substantially among different strains. Of the 35 motifs identified, eighteen had not previously been reported. Strain NIES-843 contains a larger number of total putative methyltransferase genes than have been reported previously from any bacterial genome. Genomic comparisons reveal that methyltransferases (some partial) may have been acquired from the environment through horizontal gene transfer.

METTL21B Is a Novel Human Lysine Methyltransferase of Translation Elongation Factor 1A: Discovery by CRISPR/Cas9 Knockout

Lysine methylation is widespread on human proteins, however the enzymes that catalyze its addition remain largely unknown. This limits our capacity to study the function and regulation of this modification. Here we used the CRISPR/Cas9 system to knockout putative protein methyltransferases METTL21B and METTL23 in K562 cells, to determine if they methylate elongation factor eEF1A. The known eEF1A methyltransferase EEF1AKMT1 was also knocked out as a control. Targeted mass spectrometry revealed the loss of lysine 165 methylation upon knockout of METTL21B, and the expected loss of lysine 79 methylation on knockout of EEF1AKMT1 No loss of eEF1A methylation was seen in the METTL23 knockout. Recombinant METTL21B was shown in vitro to catalyze methylation on lysine 165 in eEF1A1 and eEF1A2, confirming it as the methyltransferase responsible for this methylation site. Proteomic analysis by SILAC revealed specific upregulation of large ribosomal subunit proteins in the METTL21B knockout, and changes to further processes related to eEF1A function in knockouts of both METTL21B and EEF1AKMT1 This indicates that the methylation of lysine 165 in human eEF1A has a very specific role. METTL21B exists only in vertebrates, with its target lysine showing similar evolutionary conservation. We suggest METTL21B be renamed eEF1A-KMT3. This is the first study to specifically generate CRISPR/Cas9 knockouts of putative protein methyltransferase genes, for substrate discovery and site mapping. Our approach should prove useful for the discovery of further novel methyltransferases, and more generally for the discovery of sites for other protein-modifying enzymes.

FIRST REPORT OF GRAPEVINE SYRAH VIRUS 1 IN GRAPEVINE IN TURKEY

Grapevine Syrah virus-1 (GSyV-1) is a member of the genus Marafivirus, family Tymoviridae. This virus, originally reported from the USA, has now been reported from several Europan countries (Glasa et al., 2015) and more recently from Chile, Brazil and South Africa. Dormant canes of grapevine cvs. Syrah, Palieri and Antep karasi were collected in Turkey and screened by RT-PCR for the presence of GSyV-1, Grapevine Pinot gris virus (GPGV), Grapevine virus A (GVA) and Grapevine rupestris stem pitting-associated virus (GRSPaV). Three of the 302 samples (cvs. Syrah and Antep karasi) were found to be infected with GSyV-1 using two different primers, GSyV-1Det-F/Det-R (the putative methyltransferase gene) (Al Rwahnih et al., 2009) and GVQCP-F/R (partial CP gene) (Sabanadzovic et al., 2009). GSyV-1 was detected using both primers in cv. Syrah, whereas it was detected by only GSyV-1Det-F/Det-R in cv. Antep karasi. All PCR products were sequenced and the sequences were deposited in GenBank. Comparison of the partial methyltransferase gene sequences (KY558548 and KY558550) showed 90-98% nucleotide identity to different GSyV-1 sequences available in GenBank, while the partial CP gene sequence (KY558549) revealed 89-97% nucleotide identity to the database sequences. Nucleotide sequences of both genes shared the highest sequence identity at the nucleotide level (97-98%) with different European GSyV-1 isolates. Among the GSyV-1-positive samples, two were also infected by GPGV, GVA and GRSPaV. No particular virus-like symptoms were observed on GSyV-1-infected grapevines. To our knowledge this is the first report of GSyV-1 in Turkey.

Characterization of the biosynthetic gene cluster (ata) for the A201A aminonucleoside antibiotic from Saccharothrix mutabilis subsp. capreolus.

Antibiotic A201A produced by Saccharothrix mutabilis subsp. capreolus NRRL3817 contains an aminonucleoside (N6, N6-dimethyl-3'-amino-3'-deoxyadenosyl), a polyketide (α-methyl-p-coumaric acid) and a disaccharide moiety. The heterologous expression in Streptomyces lividans and Streptomyces coelicolor of a S. mutabilis genomic region of ~34 kb results in the production of A201A, which was identified by microbiological, biochemical and physicochemical approaches, and indicating that this region may contain the entire A201A biosynthetic gene cluster (ata). The analysis of the nucleotide sequence of the fragment reveals the presence of 32 putative open reading frames (ORF), 28 of which according to boundary gene inactivation experiments are likely to be sufficient for A201A biosynthesis. Most of these ORFs could be assigned to the biosynthesis of the antibiotic three structural moieties. Indeed, five ORFs had been previously implicated in the biosynthesis of the aminonucleoside moiety, at least nine were related to the biosynthesis of the polyketide (ata-PKS1-ataPKS4, ata18, ata19, ata2, ata4 and ata7) and six were associated with the synthesis of the disaccharide (ata12, ata13, ata16, ata17, ata5 and ata10) moieties. In addition to AtaP5, three putative methyltransferase genes are also found in the ata cluster (Ata6, Ata8 and Ata11), and no regulatory genes were found.

Rice putative methyltransferase gene OsTSD2 is required for root development involving pectin modification.

Pectin synthesis and modification are vital for plant development, although the underlying mechanisms are still not well understood. Here, we report the functional characterization of the OsTSD2 gene, which encodes a putative methyltransferase in rice. All three independent T-DNA insertion lines of OsTSD2 displayed dwarf phenotypes and serial alterations in different zones of the root. These alterations included abnormal cellular adhesion and schizogenous aerenchyma formation in the meristematic zone, inhibited root elongation in the elongation zone, and higher lateral root density in the mature zone. Immunofluorescence (with LM19) and Ruthenium Red staining of the roots showed that unesterified homogalacturonan (HG) was increased in Ostsd2 mutants. Biochemical analysis of cell wall pectin polysaccharides revealed that both the monosaccharide composition and the uronic acid content were decreased in Ostsd2 mutants. Increased endogenous ABA content and opposite roles performed by ABA and IAA in regulating cellular adhesion in the Ostsd2 mutants suggested that OsTSD2 is required for root development in rice through a pathway involving pectin synthesis/modification. A hypothesis to explain the relationship among OsTSD2, pectin methylesterification, and root development is proposed, based on pectin's function in regional cell extension/division in a zone-dependent manner.

Characterization of a DNA Adenine Methyltransferase Gene of Borrelia hermsii and Its Dispensability for Murine Infection and Persistence.

DNA methyltransferases have been implicated in the regulation of virulence genes in a number of pathogens. Relapsing fever Borrelia species harbor a conserved, putative DNA methyltransferase gene on their chromosome, while no such ortholog can be found in the annotated genome of the Lyme disease agent, Borrelia burgdorferi. In the relapsing fever species Borrelia hermsii, the locus bh0463A encodes this putative DNA adenine methyltransferase (dam). To verify the function of the BH0463A protein product as a Dam, the gene was cloned into a Dam-deficient strain of Escherichia coli. Restriction fragment analysis subsequently demonstrated that complementation of this E. coli mutant with bh0463A restored adenine methylation, verifying bh0463A as a Dam. The requirement of bh0463A for B. hermsii viability, infectivity, and persistence was then investigated by genetically disrupting the gene. The dam- mutant was capable of infecting immunocompetent mice, and the mean level of spirochetemia in immunocompetent mice was not significantly different from wild type B. hermsii. Collectively, the data indicate that dam is dispensable for B. hermsii viability, infectivity, and persistence.

Characterization of Three Tailoring Enzymes in Dutomycin Biosynthesis and Generation of a Potent Antibacterial Analogue.

The anthracycline natural product dutomycin and its precursor POK-MD1 were isolated from Streptomyces minoensis NRRL B-5482. The dutomycin biosynthetic gene cluster was identified by genome sequencing and disruption of the ketosynthase gene. Two polyketide synthase (PKS) systems are present in the gene cluster, including a type II PKS and a rare highly reducing iterative type I PKS. The type I PKS DutG repeatedly uses its active sites to create a nine-carbon triketide chain that is subsequently transferred to the α-l-axenose moiety of POK-MD1 at 4″-OH to yield dutomycin. Using a heterologous recombination approach, we disrupted a putative methyltransferase gene (dutMT1) and two glycosyltransferase genes (dutGT1 and dutGT2). Analysis of the metabolites of these mutants revealed the functions of these genes and yielded three dutomycin analogues SW140, SW91, and SW75. The major product SW91 in Streptomyces minoensis NRRL B-5482-ΔDutMT1 was identified as 12-desmethyl-dutomycin, suggesting that DutMT1 is the dedicated 12-methyltransferase. This was confirmed by the in vitro enzymatic assay. DutGT1 and DutGT2 were found to be responsible for the introduction of β-d-amicetose and α-l-axenose, respectively. Dutomycin and SW91 showed strong antibacterial activity against Staphylococcus aureus and methicillin-resistant S. aureus, whereas POK-MD1 and SW75 had no obvious inhibition, which revealed the essential role of the C-4″ triketide chain in antibacterial activity. The minimal inhibitory concentration of SW91 against the two strains was 0.125 μg mL(-1), lower than that of dutomycin (0.25 μg mL(-1)), indicating that the antibacterial activity of dutomycin can be improved through biosynthetic structural modification.

Maize OXIDATIVE STRESS2 Homologs Enhance Cadmium Tolerance in Arabidopsis through Activation of a Putative SAM-Dependent Methyltransferase Gene.

Previously the Arabidopsis (Arabidopsis thaliana) zinc finger protein OXIDATIVE STRESS2 (AtOXS2) and four OXS2-like (AtO2L) family members were described to play a role in stress tolerance and stress escape. For stress escape, SOC1 was a target of AtOXS2. However, for stress tolerance, the downstream targets were not identified. We cloned two OXS2 homolog genes from sweet corn, ZmOXS2b and ZmO2L1 Both genes are transiently inducible by Cd treatment. When expressed in Arabidopsis, each enhances tolerance against cadmium. Further analysis showed that ZmOXS2b and ZmO2L1 proteins enhance Cd tolerance in Arabidopsis by activating at least one target gene, that encoding a putative S-adenosyl-l-Met-dependent methyltransferase superfamily protein (AT5G37990), which we named CIMT1 This activation involves the in vivo interaction with a segment of the CIMT1 promoter that contains a BOXS2 motif previously identified as the binding element for AtOXS2. More importantly, CIMT1 is induced by Cd treatment, and overexpression of this gene alone was sufficient to enhance Cd tolerance in Arabidopsis. The connection of ZmOXS2b and ZmO2L1 to Arabidopsis CIMT1 suggests a similar network may exist in maize (Zea mays) and may provide a clue to possibly using a CIMT1 maize homolog to engineer stress tolerance in a major crop.

Involvement of rRNA biosynthesis in the regulation of CUC1 gene expression and pre-meristematic cell mound formation during shoot regeneration.

At an early stage of shoot regeneration from calli of Arabidopsis, pre-meristematic cell mounds develop in association with localized strong expression of CUP-SHAPED COTYLEDON (CUC) genes. Previous characterization of root initiation-defective 3 (rid3), an Arabidopsis mutant originally isolated as being temperature-sensitive for adventitious root formation, with respect to shoot regeneration implicated RID3 in the negative regulation of CUC1 expression and the restriction of cell division in pre-meristematic cell mounds. Positional cloning has identified RID3 as a WD40 repeat protein gene whose molecular function was not investigated before. Here we performed in silico analysis of RID3 and found that RID3 is orthologous to IPI3, which mediates pre-rRNA processing in Saccharomyces cerevisiae. In the rid3 mutant, rRNA precursors accumulated to a very high level in a temperature-dependent manner. This result indicates that RID3 is required for pre-rRNA processing as is IPI3. We compared rid3 with rid2, a temperature-sensitive mutant that is mutated in a putative RNA methyltransferase gene and is impaired in pre-rRNA processing, for seedling morphology, shoot regeneration, and CUC1 expression. The rid2 and rid3 seedlings shared various developmental alterations, such as a pointed-leaf phenotype, which is often observed in ribosome-related mutants. In tissue culture for the induction of shoot regeneration, both rid2 and rid3 mutations perturbed cell-mound formation and elevated CUC1 expression. Together, our findings suggest that rRNA biosynthesis may be involved in the regulation of CUC1 gene expression and pre-meristematic cell-mound formation during shoot regeneration.

Bacteriophage adenine methyltransferase: a life cycle regulator? Modelled usingVibrio harveyimyovirus like

The adenine methyltransferase (DAM) gene methylates GATC sequences that have been demonstrated in various bacteria to be a powerful gene regulator functioning as an epigenetic switch, particularly with virulence gene regulation. However, overproduction of DAM can lead to mutations, giving rise to variability that may be important for adaptation to environmental change. While most bacterial hosts carry a DAM gene, not all bacteriophage carry this gene. Currently, there is no literature regarding the role DAM plays in life cycle regulation of bacteriophage. Vibrio campbellii strain 642 carries the bacteriophage Vibrio harveyi myovirus like (VHML) that has been proven to increase virulence. The complete genome sequence of VHML bacteriophage revealed a putative adenine methyltransferase gene. Using VHML, a new model of phage life cycle regulation, where DAM plays a central role between the lysogenic and lytic states, will be hypothesized. In short, DAM methylates the rha antirepressor gene and once methylation is removed, homologous CI repressor protein becomes repressed and non-functional leading to the switching to the lytic cycle. Greater understanding of life cycle regulation at the genetic level can, in the future, lead to the genesis of chimeric bacteriophage with greater control over their life cycle for their safe use as probiotics within the aquaculture industry.

Identification of a New Gene Required for the Biosynthesis of Rhodoquinone in Rhodospirillum rubrum

Rhodoquinone (RQ) is a required cofactor for anaerobic respiration in Rhodospirillum rubrum, and it is also found in several helminth parasites that utilize a fumarate reductase pathway. RQ is an aminoquinone that is structurally similar to ubiquinone (Q), a polyprenylated benzoquinone used in the aerobic respiratory chain. RQ is not found in humans or other mammals, and therefore, the inhibition of its biosynthesis may provide a novel antiparasitic drug target. To identify a gene specifically required for RQ biosynthesis, we determined the complete genome sequence of a mutant strain of R. rubrum (F11), which cannot grow anaerobically and does not synthesize RQ, and compared it with that of a spontaneous revertant (RF111). RF111 can grow anaerobically and has recovered the ability to synthesize RQ. The two strains differ by a single base pair, which causes a nonsense mutation in the putative methyltransferase gene rquA. To test whether this mutation is important for the F11 phenotype, the wild-type rquA gene was cloned into the pRK404E1 vector and conjugated into F11. Complementation of the anaerobic growth defect in F11 was observed, and liquid chromatography-time of flight mass spectrometry (LC-TOF-MS) analysis of lipid extracts confirmed that plasmid-complemented F11 was able to synthesize RQ. To further validate the requirement of rquA for RQ biosynthesis, we generated a deletion mutant from wild-type R. rubrum by the targeted replacement of rquA with a gentamicin resistance cassette. The ΔrquA mutant exhibited the same phenotype as that of F11. These results are significant because rquA is the first gene to be discovered that is required for RQ biosynthesis.

Expression analysis of DNA methyltransferase and co-repressor genes in Quercus suberphellogen: an attempt to correlate with cork quality

Background Cork oak (Quercus suber) is one of the most important forest species in Portugal. Cork oak produces a thick cork bark which is harvested for industrial uses. Cork quality is the most important factor that affects its uses technical performance and economic value. Cork quality is associated with many features, the most relevant being the porosity resulting from the phellogen’s differentiation in filling tissue which will degenerate to lenticels. Good cork has few pores of very thin diameter being the opposite valid for low cork quality. Aiming to understand the mechanisms responsible for controlling of the molecular machinery involved in cork production, namely at the epigenetic level, it is relevant to study the expression profiles of the enzymes involved in DNA methylation in the phellogen. Methylation of cytosines in the DNA, achieved by DNMT methyltransferases, is one of the most important factors in the regulation of gene expression [1]. In plants three DNMT classes have been identified, each one with its function: the CMT (chromomethylase) class found only in plants, is responsible for maintaining the methylation in CpHpG sequences [2]; the DRM (DomainRearranged-Methyltransferase) class is associated with de novo methylation in any context [3]; and the MET class, responsible for the maintenance of methylation in CpG zones [1]. Proteins, such as the DNA methyltransferase-associated protein (DMAP1), are known to form stable complexes with DNMTs and act as co-repressors of gene expression. In this work, we report the transcriptional profile of three putative DNA methyltransferase genes from the CMT, DRM and MET classes, and one DMAP in Q. suber phellogen of trees producing good or bad quality cork.

First Report of Grapevine Syrah virus-1 in Chilean Grapevines.

At least 58 viruses have been reported to infect grapevines, causing economic damage globally. Our lab has reported previously the presence of more than 10 viral species in Chilean grapevines (2,3). Grapevine Syrah virus-1 (GSyV-1) is a novel marafivirus recently described in California vineyards (1). Grapevine virus Q (GVQ) was described shortly after GSyV-1 and both genomes share more than 99% nucleotide identity (4). Since GSyV-1 and GVQ correspond to the same viral species, the name GSyV-1 will be used in the current note to avoid confusion. Forty dormant cane samples from 12 different cultivars were collected from different regions of Chile and screened by reverse transcription-PCR. One of the 40 samples (cv. Syrah) collected from the VI region of Chile was found to be infected with GSyV-1 using two different pairs of GSyV-1-specific primers. The first pair of primers GSyV-1Det-F: 5'-CAAGCCATCCGTGCATCTGG -3' and GSyV-1Det-R: 5'-GCCGATTTGGAACCCGATGG -3' (1), was used to amplify a 297-bp fragment corresponding to a partial region of the putative methyltransferase gene. The sequence (GenBank Accession No. GU566025) shared 87% nucleotide and 100% amino acid identities with the corresponding fragment of a Californian GSyV-1 isolate (GenBank Accession No. FJ436028). Since there are no commercial antibodies available for GSyV-1 detection, a second pair of primers, GVQCP-F: 5'-TCCCAGCTTCAGGGTGAATT -3' and GVQCP-R: 5'-GCATTGCTGCGCATTGGAGG -3' (4), that amplified a 720-bp fragment of the putative coat protein gene was also used. The sequence of 720 bp from the Chilean sample (GenBank Accession No. GU566024) shared 92% nucleotide and 98% amino acid identities with the corresponding fragment of a Californian GSyV-1 isolate (GenBank Accession No. FJ436028). The GSyV-1-positive sample was also infected with Grapevine fleck virus and Grapevine rupestris stem pitting-associated virus that have been reported previously in Chile. To our knowledge, this is the first report of GSyV-1 in Chile. Further studies will help to establish the incidence and effects of this virus in Chilean grapevines.