Histidine-containing Phosphotransfer Research Articles

Exogenous GR24 Inhibits Strawberry Tillering by Affecting the Phytohormone Signaling and Sugar Metabolism Pathways

Tillering is an important part in strawberry growth, and strawberries can reproduce nutritionally through stolons to generate genetically stable offspring. However, excessive tillering during the fruit-growing stage can negatively impact fruit yield and quality. In this study, different concentrations of exogenous rac-GR24 (GR24) are used to treat the strawberry plants. It was found that GR24 effectively inhibited the sprouting of strawberry stolons, while promoting the growth of the stems and leaves. Among the treatments, the most effective concentration was found to be 5 μmol/L GR24. This treatment resulted in a decrease in the glucose content in the strawberry crowns and also caused changes in the contents of two endogenous phytohormones, gibberellic acid (GA3) and trans-zeatin riboside (tZR). Transcriptome data further suggested that exogenous GR24 may inhibit strawberry plant tillering by affecting various phytohormone signaling pathways and the sugar metabolism pathway. In 5 μmol/L GR24-treated plants, the expression level of type-B response regulator (B-ARR) was down-regulated and the expression level of CYTOKININ RESPONSE 1 (CRE1), histidine-containing phosphotransfer protein (AHP), and type-A response regulator (A-ARR) were up-regulated, suggesting the inhibition of the cytokinin (CTK) signaling pathway. The down-regulation of auxin (AUX) and auxin response factor (ARF), as well as the up-regulation of auxin/indole-3-acetic acid (AUX/IAA), led to the inhibition of the indole-3-acetic acid (IAA) signaling pathway. Additionally, the up-regulation of pyrabactin resistance 1/ pyrabactin resistance 1-like (PYR/PYL), non-fermenting 1-related protein kinase 2 (SnRK2), and ABRE binding factors (ABF) and the down-regulation of protein phosphatase 2C (PP2C) were observed in the up-regulated abscisic acid (ABA) signaling pathways. In the sugar metabolism pathway, the up-regulation of invertase (INV), hexokinase (HK), and fructokinase (FRK) and the down-regulation of trehalase (TREH) and beta-amylase (BMY) led to a decreased glucose synthesis and an increased glucose consumption. Therefore, GR24 can effectively inhibit strawberry plant tillering through these pathways, making it an effective reagent for tillering inhibition.

Genome-Wide Gene Expression Analyses of the AtfA/AtfB-Mediated Menadione Stress Response in Aspergillus nidulans.

The bZIP transcription factors (TFs) govern regulation of development, secondary metabolism, and various stress responses in filamentous fungi. In this work, we carried out genome-wide expression studies employing Illumina RNAseq to understand the roles of the two bZIP transcription factors AtfA and AtfB in Aspergillus nidulans. Comparative analyses of transcriptomes of control, ΔatfA, ΔatfB, and ΔatfAΔatfB mutant strains were performed. Dependence of a gene on AtfA (AtfB) was decided by its differential downregulation both between the reference and ΔatfA (ΔatfB) strains and between the ΔatfB (ΔatfA) and the ΔatfAΔatfB strains in vegetatively grown cells (mycelia) and asexual spores (conidia) of menadione sodium bisulfite (MSB)-treated or untreated cultures. As AtfA is the primary bZIP TF governing stress-response in A. nidulans, the number of differentially expressed genes for ΔatfA was significantly higher than for ΔatfB in both mycelial and conidial samples, and most of the AtfB-dependent genes showed AtfA dependence, too. Moreover, the low number of genes depending on AtfB but not on AtfA can be a consequence of ΔatfA leading to downregulation of atfB expression. Conidial samples showed much higher abundance of atfA and atfB mRNAs and more AtfA- and AtfB-affected genes than mycelial samples. In the presence of MSB, the number of AtfB- (but not of AtfA-) affected genes decreased markedly, which was accompanied with decreased mRNA levels of atfB in MSB-treated mycelial (reference strain) and conidial (ΔatfA mutant) samples. In mycelia, the overlap between the AtfA-dependent genes in MSB-treated and in untreated samples was low, demonstrating that distinct genes can be under AtfA control under different conditions. Carbohydrate metabolism genes were enriched in the set of AtfA-dependent genes. Among them, AtfA-dependence of glycolytic genes in conidial samples was the most notable. Levels of transcripts of certain secondary metabolitic gene clusters, such as the Emericellamide cluster, also showed AtfA-dependent regulation. Genes encoding catalase and histidine-containing phosphotransfer proteins showed AtfA-dependence under all experimental conditions. There were 23 AtfB-dependent genes that did not depend on AtfA under any of our experimental conditions. These included a putative α-glucosidase (agdB), a putative α-amylase, calA, which is involved in early conidial germination, and an alternative oxidase. In summary, in A. nidulans there is a complex interaction between the two bZIP transcription factors, where AtfA plays the primary regulatory role.

Expression study of stress-related genes in salinity-treated transgenic Arabidopsis harboring soybean Response Regulator 34

Owing to their sessile nature, plants are easily affected by various extenal factors. Among those, drought and salinity are considered as the most common stresses, which often pose a threat to plant growth and development. Major effects of the drought and salinity are interconnected and drive similar series of molecular changes in plants. These alterations in response to the stress are under the regulation of various signaling pathways, including the engangement of evolutionarily conserved two-component systems (TCSs). Three components with distinct functions can be found in a functional TCS, which are histidine kinases (HKs), histidine-containing phosphotransfer proteins (HPts), and response regulator proteins (RRs). Previous research revealed that the soybean (Glycine max) GmRR34 acts as an important regulatory protein in plants under drought stress conditions. In this project, the investigation on the role of GmRR34 in osmotic stress responses was extended to salinity by examining the expression of a subset of salinity-responsive genes using RT-qPCR method. Our analyses showed that the transgenic Arabidopsis plants ectopically expressing GmRR34 displayed enhanced expression of several important stress-related genes, including Catalase 1 (CAT1), Stromal ascorbate peroxidase 1 (sAPX1), Copper/zinc superoxide dismutase 1 (CSD1), Sodium/hydrogen exchanger 1 (NHX1) and Salt overly sensitive 2 (SOS2). These results indicate that GmRR34-transgenic plants might be more salt-tolerant thanks to stronger activities of antioxidant enzymes and better capacity in maintaining cytosolic ion homeostasis. Therefore, it is highlighted the necessity to perform further studies to fully characterize the GmRR34 biological functions as well as explore its application potential in enhancing the salt tolerance of crop plants.

Diurnal control of intracellular distributions of PAS-Histidine kinase 1 and its interactions with partner proteins in the moss Physcomitrium patens

In multi-step phosphorelay (MSP) signaling, upon reception of various environmental signals, histidine kinases (HKs) induce autophosphorylation and subsequent phosphotransfer to partner histidine-containing phosphotransfer proteins (HPts). Recently, we reported that (i) two Per-Arnt-Sim (PAS) domain-containing HKs (PHK1 and PHK2) of the moss Physcomitrium (Physcomitrella) patens suppressed red light-induced branching of protonema tissue, and (ii) they interacted with partner HPts (HPt1 and HPt2) in the nucleus in the dark while cytoplasmic interactions also occurred under red light. Here we demonstrate that PHK1 is diurnally regulated, i.e., it is localized and interacts with HPt1 and HPt2 in the nucleus at night whereas these activities reversibly expand and become nucleocytoplasmic in the day. In the dark, PHK1 interacts with HPts only in the nucleus, even in subjective daytime, indicating that endogenous regulation by the circadian clock is not involved. These results suggest that PHK1 is a regulator of moss’ adaptation to a light environment on a daily timescale. We discuss a possible regulatory mechanism for the branching of protonema.

Influence of Light of Different Spectral Compositions on the Growth, Photosynthesis, and Expression of Light-Dependent Genes of Scots Pine Seedlings.

Varying the spectral composition of light is one of the ways to accelerate the growth of conifers under artificial conditions for the development of technologies and to obtain sustainable seedlings required to preserve the existing areas of forests. We studied the influence of light of different quality on the growth, gas exchange, fluorescence indices of Chl a, and expression of key light-dependent genes of Pinus sylvestris L. seedlings. It was shown that in plants growing under red light (RL), the biomass of needles and root system increased by more than two and three times, respectively, compared with those of the white fluorescent light (WFL) control. At the same time, the rates of photosynthesis and respiration in RL and blue light (BL) plants were lower than those of blue red light (BRL) plants, and the difference between the rates of photosynthesis and respiration, which characterizes the carbon balance, was maximum under RL. RL influenced the number of xylem cells, activated the expression of genes involved in the transduction of cytokinin (Histidine-containing phosphotransfer 1, HPT1, Type-A Response Regulators, RR-A) and auxin (Auxin-induced protein 1, Aux/IAA) signals, and reduced the expression of the gene encoding the transcription factor phytochrome-interacting factor 3 (PIF3). It was suggested that RL-induced activation of key genes of cytokinin and auxin signaling might indicate a phytochrome-dependent change in cytokinins and auxins activity.

Defective cytokinin signaling reprograms lipid and flavonoid gene-to-metabolite networks to mitigate high salinity in Arabidopsis

Significance The regulatory roles of cytokinin (CK) signaling on metabolic plasticity of plant response to salt stress remain widely unknown. A comprehensive metabolome and transcriptome analysis of CK-signaling–defective Arabidopsis thaliana histidine-containing phosphotransfer protein ahp2,3,5 and type-B Arabidopsis response regulator arr1,10,12 triple mutants under nonsaline and saline conditions revealed that CK signaling induces a reprogramming of gene-to-metabolite networks involved in Arabidopsis response to salinity. CK signaling modulates prestress and poststress accumulations of sugars, amino acids, and anthocyanins as well as membrane lipid reprogramming as an emerging mechanism of salinity adaptation in Arabidopsis . Our results provide insights into CK-signaling–mediated regulation of gene-to-metabolite networks in response to salt stress, enabling the efficient application of CK biology in stress tolerance-oriented plant biotechnology.

3D Domain Swapping Dimerization of the Receiver Domain of Cytokinin Receptor CRE1 From Arabidopsis thaliana and Medicago truncatula.

Cytokinins are phytohormones regulating many biological processes that are vital to plants. CYTOKININ RESPONSE1 (CRE1), the main cytokinin receptor, has a modular architecture composed of a cytokinin-binding CHASE (Cyclases/Histidine kinases Associated Sensory Extracellular) domain, followed by a transmembrane fragment, an intracellular histidine kinase (HK) domain, and a receiver domain (REC). Perception of cytokinin signaling involves (i) a hormone molecule binding to the CHASE domain, (ii) CRE1 autophosphorylation at a conserved His residue in the HK domain, followed by a phosphorelay to (iii) a conserved Asp residue in the REC domain, (iv) a histidine-containing phosphotransfer protein (HPt), and (v) a response regulator (RR). This work focuses on the crystal structures of the REC domain of CRE1 from the model plant Arabidopsis thaliana and from the model legume Medicago truncatula. Both REC domains form tight 3D-domain-swapped dimers. Dimerization of the REC domain agrees with the quaternary assembly of the entire CRE1 but is incompatible with a model of its complex with HPt, suggesting that a considerable conformational change should occur to enable the signal transduction. Indeed, phosphorylation of the REC domain can change the HPt-binding properties of CRE1, as shown by functional studies.

Downregulation of the ypdA Gene Encoding an Intermediate of His-Asp Phosphorelay Signaling in Aspergillus nidulans Induces the Same Cellular Effects as the Phenylpyrrole Fungicide Fludioxonil.

Many eukaryotic histidine-to-aspartate (His-Asp) phosphorelay systems consist of three types of signal transducers: a His-kinase (HK), a response regulator (RR), and a histidine-containing phosphotransfer intermediate (HPt). In general, the HPt acts as an intermediate between the HK and the RR and is indispensable for inducing appropriate responses to environmental stresses. In a previous study, we attempted but were unable to obtain deletion mutants of the ypdA gene in order to characterize its function in the filamentous fungus Aspergillus nidulans. In the present study, we constructed the CypdA strain in which ypdA expression is conditionally regulated by the A. nidulans alcA promoter. We constructed CypdA strains with RR gene disruptions (CypdA-sskAΔ, CypdA-srrAΔ, and CypdA-sskAΔsrrAΔ). Suppression of YpdA induced by ypdA downregulation activated the downstream HogA mitogen-activated protein kinase cascade. YpdA suppression caused severe growth defects and abnormal hyphae, with features such as enhanced septation, a decrease in number of nuclei, nuclear fragmentation, and hypertrophy of vacuoles, both regulated in an SskA-dependent manner. Fludioxonil treatment caused the same cellular responses as ypdA suppression. The growth-inhibitory effects of fludioxonil and the lethality caused by ypdA downregulation may be caused by the same or similar mechanisms and to be dependent on both the SskA and SrrA pathways.

Red light-regulated interaction of Per-Arnt-Sim histidine kinases with partner histidine-containing phosphotransfer proteins in Physcomitrium patens.

Multi-step phosphorelay (MSP) is a broadly distributed signaling system in organisms. In MSP, histidine kinases (HKs) receive various environmental signals and transmit them by autophosphorylation followed by phosphotransfer to partner histidine-containing phosphotransfer proteins (HPts). Previously, we reported that Per-Arnt-Sim (PAS) domain-containing HK1 (PHK1) and PHK2 of the moss Physcomitrium (Physcomitrella) patens repressed red light-induced protonema branching, a critical step in the moss life cycle. In plants, PHK homolog-encoding genes are conserved only in early-diverging lineages such as bryophytes and lycophytes. PHKs-mediated signaling machineries attract attention especially from an evolutionary viewpoint, but they remain uninvestigated. Here, we studied the P. patens PHKs focusing on their subcellular patterns of localization and interaction with HPts. Yeast two-hybrid analysis, a localization assay with a green fluorescent protein, and a bimolecular fluorescence complementation analysis together showed that PHKs are localized and interact with partner HPts mostly in the nucleus, as unprecedented features for plant HKs. Additionally, red light triggered the interactions between PHKs and HPts in the cytoplasm, and light co-repressed the expression of PHK1 and PHK2 as well as genes encoding their partner HPts. Our results emphasize the uniqueness of PHKs-mediated signaling machineries, and functional implications of this uniqueness are discussed.

Histidine Kinases: Diverse Functions in Plant Development and Responses to Environmental Conditions.

The two-component system (TCS), which is one of the most evolutionarily conserved signaling pathway systems, has been known to regulate multiple biological activities and environmental responses in plants. Significant progress has been made in characterizing the biological functions of the TCS components, including signal receptor histidine kinase (HK) proteins, signal transducer histidine-containing phosphotransfer proteins, and effector response regulator proteins. In this review, our scope is focused on the diverse structure, subcellular localization, and interactions of the HK proteins, as well as their signaling functions during development and environmental responses across different plant species. Based on data collected from scientific studies, knowledge about acting mechanisms and regulatory roles of HK proteins is presented. This comprehensive summary ofthe HK-related network provides a panorama of sophisticated modulating activities of HK members and gaps in understanding these activities, as well as the basis for developing biotechnological strategies to enhance the quality of crop plants.

Sugars enhance parthenocarpic fruit formation in cucumber by promoting auxin and cytokinin signaling

Parthenocarpy is an important agricultural trait that determines the yield of cucumber. The role of sugars in parthenocarpic fruit formation is unknown. Therefore, we investigated these factors by using one highly parthenocarpic line DDX and one weakly parthenocarpic line ZK. To identify the possible effect of photosynthesis on parthenocarpy, leaf of ZK and DDX were covered for limiting the synthesis of carbohydrates. Leaf covering inhibited parthenocarpic fruit initiation and growth. Sugars (sucrose, fructose and glucose) contents in CPPU-induced, pollinated fruit of ZK and non-pollinated fruit of DDX were higher than those in non-pollinated fruit of ZK. The exogenous application of sugars (especially fructose and sucrose) significantly induced the parthenocarpic fruit set and growth. Transcriptomes of fruits treated with and without exogenously applied sugars showed that genes involved in auxin signaling and cytokinin signaling were more strongly expressed in the treated fruits. Auxin responsive gene IAA14, and cytokinin responsive genes encoding histidine-containing phosphotransfer protein 4 and two-component response regulator 17 were upregulated in sugar-induced parthenocarpic fruits. These results show that parthenocarpic fruit formation is regulated by the interplay among sugars and the plant hormones auxin and cytokinin.

The Journey from Two-Step to Multi-Step Phosphorelay Signaling Systems.

BackgroundThe two-component signaling (TCS) system is an important signal transduction machinery in prokaryotes and eukaryotes, excluding animals, that uses a protein phosphorylation mechanism for signal transmission.ConclusionProkaryotes have a primitive type of TCS machinery, which mainly comprises a membrane-bound sensory histidine kinase (HK) and its cognate cytoplasmic response regulator (RR). Hence, it is sometimes referred to as two-step phosphorelay (TSP). Eukaryotes have more sophisticated signaling machinery, with an extra component - a histidine-containing phosphotransfer (HPT) protein that shuttles between HK and RR to communicate signal baggage. As a result, the TSP has evolved from a two-step phosphorelay (His–Asp) in simple prokaryotes to a multi-step phosphorelay (MSP) cascade (His–Asp–His–Asp) in complex eukaryotic organisms, such as plants, to mediate the signaling network. This molecular evolution is also reflected in the form of considerable structural modifications in the domain architecture of the individual components of the TCS system. In this review, we present TCS system's evolutionary journey from the primitive TSP to advanced MSP type across the genera. This information will be highly useful in designing the future strategies of crop improvement based on the individual members of the TCS machinery.

Annotation of Plant Genome: A Case Study of Oryza sativa

Rice! A perennial claim crop of the world. Besides satisfying the eager of energy rice, has also been known to support worlds trade economy. Hence, being a crop of such crucial importance its examinational study at genome level will serve in multiplying its production and quality to irrigate the burning crave of humanity. Likewise, the senescence gene of rice is responsible for its age duration. Hence, understanding its property at 360° will help us to modify or to alter its function in positive portion. Using Insilco analysis mode, the present study is an attempt to examine various characteristics conformation of senescence causing gene in rice. The two gene chosen were HCP and RR because, the interaction in between these two led to the onset of senescence in rice. Two gene that is HCP (Histidine-containing phosphotransfer protein 1) and RR (Two-component response regulator) are responsible for attaining the stage of senescence in rice. Understanding their molecular and structural property will be going to let us closer to perform successful adjustments. Moreover, their specific property is also responsible for their specific interaction which led to generation of such signals that triggers senescence. Therefore, this analysis was aimed to understand the features of the two genes as well as their interaction by the means of computational technique. Understanding the features, function and flow of gene will lead us to stabilized effective measure in order to get a beneficiary outcome while going for alteration in its characters. As the pure data for the structure conformation of the selected genes are not available so, we have at first, searched the most similar homolog of the query sequence and the search was based on similar sequence homology on the platform of local alignment tool. And further analysis was carried out on the base conformation of the most relevant homologs (structure/sequence) found. We have analyze the query gene sequence by various dry lab analysis tool to explore its structural and molecular features with the motive to contribute a little knowledge for the sake of further studies to delay senescence in rice plant in order to increase grain productivity.

Structural insights into the histidine-containing phosphotransfer protein and receiver domain of sensor histidine kinase suggest a complex model in the two-component regulatory system inPseudomonas aeruginosa

In Pseudomonas aeruginosa, an important opportunistic pathogen that causes numerous acute and chronic infections, the hybrid two-component system (TCS) regulates the swarming ability and biofilm formation with a multistep phospho-relay, and consists of hybrid-sensor histidine kinase (HK), histidine-containing phospho-transfer protein (Hpt) and response regulator (RR). In this work, two crystal structures of HptB and the receiver domain of HK PA1611 (PA1611REC) of P. aeruginosa have been determined in order to elucidate their interactions for the transfer of the phospho-ryl group. The structure of HptB folds into an elongated four-helix bundle - helices α2, α3, α4 and α5, covered by the short N-terminal helix α1. The imidazole side chain of the conserved active-site histidine residue His57, located near the middle of helix α3, protrudes from the bundle and is exposed to solvent. The structure of PA1611REC possesses a conventional (β/α)5 topology with five-stranded parallel β-sheets folded in the central region, surrounded by five α-helices. The divalent Mg2+ ion is located in the negatively charged active-site cleft and interacts with Asp522, Asp565 and Arg567. The HptB-PA1611REC complex is further modeled to analyze the binding surface and interactions between the two proteins. The model shows a shape complementarity between the convex surface of PA1611REC and the kidney-shaped HptB with fewer residues and a different network involved in interactions compared with other TCS complexes, such as SLN1-R1/YPD1 from Saccharomyces cerevisiae and AHK5RD/AHP1 from Arabidopsis thaliana. These structural results provide a better understanding of the TCS in P. aeruginosa and could potentially lead to the discovery of a new treatment for infection.

The Interaction Network and Signaling Specificity of Two-Component System in Arabidopsis.

Two-component systems (TCS) in plants have evolved into a more complicated multi-step phosphorelay (MSP) pathway, which employs histidine kinases (HKs), histidine-containing phosphotransfer proteins (HPts), and response regulators (RRs) to regulate various aspects of plant growth and development. How plants perceive the external signals, then integrate and transduce the secondary signals specifically to the desired destination, is a fundamental characteristic of the MSP signaling network. The TCS elements involved in the MSP pathway and molecular mechanisms of signal transduction have been best understood in the model plant Arabidopsis thaliana. In this review, we focus on updated knowledge on TCS signal transduction in Arabidopsis. We first present a brief description of the TCS elements; then, the protein–protein interaction network is established. Finally, we discuss the possible molecular mechanisms involved in the specificity of the MSP signaling at the mRNA and protein levels.

Acetylation of BcHpt Lysine 161 Regulates Botrytis cinerea Sensitivity to Fungicides, Multistress Adaptation and Virulence.

BcHpt is a core element of the high-osmolarity glycerol (HOG) transduction pathway in Botrytis cinerea. In contrast to other elements of the pathway, which have been characterized and proven to play important roles in vegetative differentiation, fungicide resistance, the multistress response, and virulence in B. cinerea, BcHpt (Histidine-containing phosphotransfer) is essential but uncharacterized in B. cinerea. Our previous study reported the first lysine acetylation site (Lys161) in BcHpt. In this study, the functions of this lysine acetylation site in BcHpt were characterized using site-directed mutagenesis. To mimic Lys161 acetylation, we generated the mutant strain ΔBcHPt + BcHptK161Q-GFP, which exhibited a slower growth rate; lower pathogenicity; higher sensitivity to multiple stresses, including osmotic and oxidative stresses, dicarboximides, and demethylation inhibitors (DMIs); and lower BcSak1 phosphorylation levels than wild-type B. cinerea. Constitutive acetylation of BcHpt Ly161 apparently inhibits hyphal growth, the multistress response, and sensitivity to fungicides in B. cinerea. Moreover, the lysine acetylation site affected phosphorylation of the MAPK BcSak1.

Nitric Oxide Enters Quorum Sensing via the H-NOX Signaling Pathway in Vibrio parahaemolyticus.

Nitric oxide (NO) plays a major role in the regulation of mammalian biological functions. In recent years, NO has also been implicated in bacterial life cycles, including in the regulation of biofilm formation, and the metabolism of the bacterial second messenger signaling molecule cyclic-di-GMP. In a previous study, we reported the discovery of an NO-responsive quorum sensing (QS) circuit in Vibrio harveyi. Here, we characterize the homologous QS pathway in Vibrio parahaemolyticus. Spectroscopic analysis shows V. parahaemolyticus H-NOX is an NO sensory protein that binds NO in 5/6-coordinated mixed manner. Further, we demonstrate that through ligation to H-NOX, NO inhibits the autophosphorylation activity of an H-NOX-associated histidine kinase (HqsK; H-NOX-associated quorum sensing kinase) that transfers phosphate to the Hpt (histidine-containing phosphotransfer protein) protein LuxU. Indeed, among the three Hpt proteins encoded by V. parahaemolyticus, HqsK transfers phosphate only to the QS-associated phosphotransfer protein LuxU. Finally, we show that NO promotes transcription of the master quorum sensing regulatory gene opaR at low cell density.

Phenotypic and molecular traits determine the tolerance of olive trees to drought stress

Olive trees are known for their capacity to adapt to drought through several phenotypic and molecular variations, although this can vary according to the different provenances of the same olive cultivar. We confronted the same olive cultivar from two different location in Spain: Freila, in the Granada province, with low annual precipitation, and Grazalema, in the Cadiz province, with high annual precipitation, and subjected them to five weeks of severe drought stress. We found distinctive physiological and developmental adaptations among the two provenances. Thus, trees from Freila subjected to drought stress exhibited increasing root dry weights and decreasing leaf numbers and relative stem heights. On the other hand, the treatment with drought in Grazalema trees reduced their leaf chlorophyll contents, but increased their relative stem diameter and their root hydraulic conductivity. The physiological responses of Freila tree roots to drought were linked to different molecular adaptations that involved the regulation of genes related to transcription factors induced by ABA, auxin and ethylene signaling, as well as, the action of a predicted membrane intrinsic protein (MIP). On the other hand, the responses of Grazalema trees were related with different root genes related to oxidation-reduction, ATP synthesis, transduction and posttranslational regulation, with a special mention to the cytokinins signaling through the transcript predicted as a histidine-containing phosphotransfer protein. Our results show that olive trees adapted to dry environments will adjust their growth and water uptake capacity through transcription factors regulation, and this will influence the different physiological responses to drought stress.

Light-Regulated Alternative Splicing of Pseudo-Histidine Phosphotransfer Protein 3 in Oryza sativa

The two-component system is involved in several developmental events and different responses to the environment. Histidine-containing phosphotransfer proteins (HPs) play a critical role in transferring the phosphoryl group in the nucleus and regulating downstream effectors. Two authentic-HPs (OsAHPs) and three pseudo-HPs (OsPHPs) have been identified in rice. The conserved phosphorylation residue does not occur in OsPHPs, which are proposed as negative regulators in the cytokinin two-component system. One of the OsPHPs, OsPHP3, in rice is highly expressed at root caps. However, the roles of OsPHP3 have not been investigated in rice. We detected two major alternative splicing mRNAs of OsPHP3 and determined the expression in response to different environmental stimuli. The ratio of the two major alternative splicing OsPHP3 variants was significantly altered in response to a light signal and tissue specificity. Additionally, the results also indicated the positive regulation of auxin in the transcription of OsPHP3 in the root, and the ratio of the expression of the two major alternative splicing OsPHP3s was altered. OsPHP3 was also involved in auxin- and cytokinin-regulated lateral root development. Collectively, these results indicate a possible regulation of alternative splicing OsPHP3 isoforms by light and their roles in rice lateral root development.

Chemical shift assignments of the catalytic and ATP-binding domain of HK853 from Thermotoga maritime.

HK853 is a transmembrane protein from Thermotoga maritime, which belongs to HK853/RR468 two-component signal transduction system (TCS) and acts as a sensor histidine kinase. HK853 is mainly composed of a transmembrane domain, dimerization and histidine-containing phosphotransfer domain (HK853DHp), catalytic and ATP-binding domain (HK853CA) and several linkers. HK853 can be completely autophosphorylated, which is the first step for signal transduction of TCS. HK853CA is an essential domain for its kinase function, since HK853CA could bind with ATP and convert it to ADP. Here, we report the backbone and part of side chain assignments of HK853CA. By analyzing the chemical shifts of HN, N, CO, Cα and Cβ, the secondary structure was predicted and contrasted with the published crystal structure of HK853CA. The result showed that our predicted structure could basically fit into the crystal structure. Thus, the chemical shift assignments of HK853CA are the starting point for further structural and dynamics study.