Phytotoxic Peptides Research Articles

Production of phytotoxic cationic α-helical antimicrobial peptides in plant cells using inducible promoters.

Synthetic linear antimicrobial peptides with cationic α-helical structures, such as BP100, have potent and specific activities against economically important plant pathogenic bacteria. They are also recognized as valuable therapeutics and preservatives. However, highly active BP100 derivatives are often phytotoxic when expressed at high levels as recombinant peptides in plants. Here we demonstrate that production of recombinant phytotoxic peptides in transgenic plants is possible by strictly limiting transgene expression to certain tissues and conditions, and specifically that minimization of this expression during transformation and regeneration of transgenic plants is essential to obtain viable plant biofactories. On the basis of whole-genome transcriptomic data available online, we identified the Os.hsp82 promoter that fulfilled this requirement and was highly induced in response to heat shock. Using this strategy, we generated transgenic rice lines producing moderate yields of severely phytotoxic BP100 derivatives on exposure to high temperature. In addition, a threshold for gene expression in selected tissues and stages was experimentally established, below which the corresponding promoters should be suitable for driving the expression of recombinant phytotoxic proteins in genetically modified plants. In view of the growing transcriptomics data available, this approach is of interest to assist promoter selection for specific purposes.

Involvement of a phytotoxic peptide in the development of the Northern leaf blight of corn

Non pathogenic isolates ofExserohilum turcicum successfully infect corn plants in the presence of syntheticE. turcicum toxin during inoculation. The toxin significantly increased the number of appressoria and the ramification of germinating conidia both on host leaves and on artificial media. These findings indicate that this toxin plays an important role in infection of Northern leaf blight.

Tentoxin sensitivity of chloroplasts determined by codon 83 of beta subunit of proton-ATPase.

Tentoxin is a naturally occurring phytotoxic peptide that causes seedling chlorosis and arrests growth in sensitive plants and algae. In vitro, it inhibits activity of the beta subunit of the plastid proton-adenosine triphosphatase (ATPase) from sensitive species. Plastid atpB genes from six closely related, tentoxin-sensitive or -resistant Nicotiana species differ at codon 83, according to their response to the toxin: glutamate correlated with resistance and aspartate correlated with sensitivity. The genetic relevance of this site was confirmed in Chlamydomonas reinhardtii by chloroplast transformation. The alga, normally tentoxin-resistant, was rendered tentoxin-sensitive by mutagenesis of its plastid atpB gene at codon 83. Codon 83 may represent a critical site on the beta subunit that does not compete with nucleotide binding or other catalytic activities.

Comparison of Verticillium dahliae-produced phytotoxic peptides purified from culture fluids and infected potato stems

Phytotoxins produced by a strain of Verticillium dahliae pathogenic on potato have been purified from culture fluids and xylem extracts of potato stems infected by the fungus. The toxins were very similar to each other in molecular mass (approximately 1000 D), HPLC profile, amino acid composition, biological activity and antigenic cross-reactivity. Visible Verticillium wilt symptoms were observed when either peptide, in amounts as low as 20 ng (2 × 10 −6 mol), was injected into detached potato leaves. The differential activity of the peptides on hosts and non-hosts of the fungus, as well as on susceptible and tolerant cultivars, indicated host specific properties. An immunofluorescence assay detected the toxin in potato stems before extensive colonization occurred, suggesting that the toxin may be translocated in advance of the growing hyphae.

Structure-activity relationships of cyclic and acyclic analogues of the phytotoxic peptide tentoxin

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructure-activity relationships of cyclic and acyclic analogues of the phytotoxic peptide tentoxinJudson V. Edwards, Alan R. Lax, Eivind B. Lillehoj, and Gordon J. BoudreauxCite this: J. Agric. Food Chem. 1987, 35, 4, 451–456Publication Date (Print):July 1, 1987Publication History Published online1 May 2002Published inissue 1 July 1987https://doi.org/10.1021/jf00076a003RIGHTS & PERMISSIONSArticle Views97Altmetric-Citations13LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (826 KB) Get e-Alerts Get e-Alerts

Cyclic peptides

A cyclic tetradepsipeptide with a sequence corresponding to AM-toxin III (a phytotoxic peptide) was synthesized by a conventional method in order to confirm the proposed structure. This was mediated through a deamination reaction of precursor cyclotetradepsipeptide containing a D-2, 3-diaminopropionic acid residue by the Hofmann degradation method. The synthetic peptide and natural AM-toxin III were identical in regard to t.l.c., crystal form, mass spectrum and biological activity in causing necrosis on apple leaves. Two analogs, [l-O-methyl-L-tyrosine]-AM-toxin and [l-L-tyrosine]-AM-toxin showed extremely weak activity; the relationship between the bulkiness of an aromatic side chain at position 1 of AM-toxin III and its biological activity is discussed.

ChemInform Abstract: CYLIC PEPTIDES. VII. SYNTHESIS AND CONFORMATION OF DIASTEREOMERIC ANALOGS OF CYL‐2 CONTAINING L‐PROLINE AND L‐LEUCINE

Two diastereomeric cyclic tetrapeptides with a sequence of cyclo (-D (and L)-Tyr (me)-L-Ile-L-Pro-L-Leu-) (ID and IL) have been synthesized, which are simplified analogs of a phytotoxic peptide Cyl-2, and contain an L-proline and an L-leucine residue in place of an L-pipecolic acid and a 2-amino-8-oxo-9,10-epoxydecanoic acid residue, respectively, in Cyl-2. The cyclization of the H-D-Tyr(Me)-L-Ile-L-Pro-L-Leu-ONSu proceeded smoothly to give ID in excellent yield (50%), but the cyclization of H-L-Tyr(Me)-L-Ile-L-Pro-L-Leu-ONSu gave IL in much lower yield (10%). Based on the results of 1H- and 13C-n.m.r. studies, differential N-methylation and model buildings of ID, the backbone structure of ID has been proposed to be a unique trans-trans-cis-trans conformation, the L-Ile-L-Pro bond being cis.

CYLIC PEPTIDES

Two diastereomeric cyclic tetrapeptides with a sequence of cyclo (‐D (and L)‐Tyr (Me)‐L‐Ile‐L‐Pro‐L‐Leu‐) (ID and IL) have been synthesized, which are simplified analogs of a phytotoxic peptide Cyl‐2, and contain an L‐proline and an L‐leucine residue in place of an L‐pipecolic acid and a 2‐amino‐8‐oxo‐9,10‐epoxydecanoic acid residue, respectively, in Cyl‐2. The cyclization of the H‐D‐Tyr(Me)‐L‐Ile‐L‐Pro‐L‐Leu‐ONSu proceeded smoothly to give ID in excellent yield (50%), but the cyclization of H‐L‐Tyr(Me)‐L‐Ile‐L‐Pro‐L‐Leu‐ONSu gave IL in much lower yield (10%).Based on the results of 1H‐ and 13C‐n.m.r. studies, differential N‐methylation and model buildings of ID, the backbone structure of ID has been proposed to be a unique trans‐trans‐cis‐trans conformation, the L‐Ile‐L‐Pro bond being cis.

α‐デヒドロアミノ酸の合成

Synthetic studies on α-dehydroamino acid (DHA) derivatives, which are very important constituents in an increasing number of antibiotic and phytotoxic peptides, were reviewed according to the following articles : 1. Introduction.2. Synthesis of DHA.2.1. From unsaturated azlactones. 2.2. Elimination of β-substituents. 2.3. Reduction of α-nitro-α-alkenoic esters. 2.4. Condensation of α-keto esters with phosphinimines. 2.5. Condensation of α-keto acids with nitriles or amides. 2.6. Elimination of N-or α-substituents. 2.7. Reduction of α-azido α-alkenoic esters 35. 2.8. Reduction of 35 with phosphins or phosphites.3. Synthesis of β-substituted-DHA.3.1. β-Halo-DHA, 3.2. β-Nitro-and azido-DELA. 3.3. β-Amino-DHA.

CYCLIC PEPTIDES

A cyclic tetradepsipeptide with a sequence corresponding to AM-toxin II (a phytotoxic peptide) was synthesized in order to confirm the proposed structure by a conventional method. This was mediated through a dehydration reaction of cyclodepsipeptide containing a D-Ser residue, by methanesulfonyl chloride containing sulfur dioxide. The synthetic peptide and natural AM-toxin II were identical as regards t.l.c., crystal form, several kinds of spectra measurements and biological activity in causing necrosis on apple leaves. An analog, [L-Phe1]-AM-toxin, containing the lower homolog (L-phenylalanine) instead of L-2-amino-5-phenylpentanoic acid in position 1 of natural toxin II, was synthesized simultaneously. [L-Phe1]-AM-toxin showed extremely weak activity; the relationship between the bulkiness of an aromatic side chain and the biological activity of AM-toxin II is discussed.

THE ROLE OF DEHYDROALANINES IN ENZYME AND PEPTIDE CHEMISTRY : ENZİM VE PEPTİD KİMYASINDA DEHİDROALANİNLERİN ROLÜ

-Dehydroamino acids represent an important class of compound as they are keyintermediates in amino acid and peptide synthesis and are constituents of a variety of naturally occurring antibiotic and phytotoxic peptides including several fungal metabolites which posses antibiotic activity. They also play an important role at the active site of some enzymes and show free radical scavenging activity. It is believed that more detailed investigations are necessary to understand the importance of dehydroalanines.