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Gluconate Metabolism Is Required for Virulence of the Soft-Rot Pathogen Pectobacterium carotovorum

October 2010 , Volume 23 , Number  10
Pages  1,335 - 1,344

Beth Mole,1,2 Sohrab Habibi,3 Jeffery L. Dangl,1,2,4,5 and Sarah R. Grant1,4

1Department of Biology, 2Department of Microbiology and Immunology, 3Director, Mass Spectrometry Facility, Department of Chemistry, 4Curriculum in Genetics and Molecular Biology, and 5Carolina Center for Genome Sciences, University of North Carolina, Chapel Hill 27599, U.S.A.

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Accepted 27 June 2010.

Pectobacterium carotovorum is a ubiquitous soft rot pathogen that uses global virulence regulators to coordinate pathogenesis in response to undefined environmental conditions. We characterize an operon in P. carotovorum required for gluconate metabolism and virulence. The operon contains four genes that are highly conserved among proteobacteria (initially annotated ygbJKLM), one of which was misassigned as a type III secreted effector, (ygbK, originally known as hopAN1). A mutant with a deletion-insertion within this operon is unable to metabolize gluconate, a precursor for the pentose phosphate pathway. The mutant exhibits attenuated growth on the leaves of its host of isolation, potato, and those of Arabidopsis thaliana. Notably, the mutant hypermacerates potato tubers and is deficient in motility. Global virulence regulators that are responsive to cell wall pectin breakdown products and other undefined environmental signals, KdgR and FlhD, respectively, are misregulated in the mutant. The alteration of virulence mediated via changes in transcription of known global virulence regulators in our ygbJ-M operon mutant suggests a role for host-derived catabolic intermediates in P. carotovorum pathogenesis. Thus, we rename this operon in P. carotovorum vguABCD for virulence and gluconate metabolism.

© 2010 The American Phytopathological Society