IDENTIFICATION OF A LYSA-LIKE GENE REQUIRED FOR TABTOXIN BIOSYNTHESIS AND PATHOGENICITY IN PSEUDOMONAS-SYRINGAE PV-TABACI STRAIN PTBR2.024

被引:15
作者
ENGST, K
SHAW, PD
机构
[1] Department of Plant Pathology, University of Illinois
关键词
DAPD; GUG; PSEUDOMONAS-SYRINGAE PV-TABACI STRAIN BR2;
D O I
10.1094/MPMI-5-322
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Pseudomonas syringae pv. tabaci strain PTBR2.024 produces tabtoxin and causes wildfire disease on tobacco and green bean. PTBR7.000, a Tn5 mutant of PTBR2.024, does not produce tabtoxin, is nonpathogenic on tobacco, and is prototrophic. A 3-kb fragment from a genomic library of the parent strain PTBR2.024 complemented both mutant phenotypes. This 3-kb fragment contains two open reading frames (ORFs), ORF1 and ORF2, and two truncated ORFs, ORF3 and ORF4. The Tn5 insert in PTBR7.000 was mapped to ORF2, and complementation studies showed that an intact ORF2 was sufficient to restore tabtoxin production and pathogenicity. The deduced amino acid sequences of ORF2 and truncated ORF3 contain significant homology to bacterial lysine biosynthetic enzymes, diaminopimelate decarboxylase, and DELTA1-piperidine-2,6-dicarboxylate succinyl transferase, respectively. ORF2, however, is not required for lysine biosynthesis. We designated the sequence corresponding to ORF2 as gene tabA and propose that the product of tabA is an enzyme in the tabtoxin biosynthetic pathway that recognizes a substrate analogue of a compound in the lysine biosynthetic pathway.
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页码:322 / 329
页数:8
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