제목 | Disruption of the metC Gene Affects Methionine Biosynthesis in Pectobacterium carotovorum subsp. carotovorum Pcc21 and Reduces Soft-Rot Disease |
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내용 |
Plant pathogenic Pectobacterium species cause severe
soft rot/blackleg diseases in many economically important crops worldwide. Pectobacterium utilizes plant cell
wall degrading enzymes (PCWDEs) as the main virulence determinants for its pathogenicity. In this study,
we screened a random mutant, M29 is a transposon
insertion mutation in the metC gene encoding cystathionine β-lyase that catalyzes cystathionine to homocysteine at the penultimate step in methionine biosynthesis.
M29 became a methionine auxotroph and resulted in
growth defects in methionine-limited conditions. Impaired growth was restored with exogenous methionine
or homocysteine rather than cystathionine. The mutant exhibited reduced soft rot symptoms in Chinese
cabbages and potato tubers, maintaining activities of
PCWDEs and swimming motility. The mutant was unable to proliferate in both Chinese cabbages and potato
tubers. The reduced virulence was partially restored
by a complemented strain or 100 µM of methionine,
whereas it was fully restored by the extremely high
concentration (1 mM). Our transcriptomic analysis
showed that genes involved in methionine biosynthesis
or transporter were downregulated in the mutant. Our
results demonstrate that MetC is important for methionine biosynthesis and transporter and influences its
virulence through Pcc21 multiplication in plant hosts.
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첨부 |