PMID:22493725

Citation	Kirchberg, J, Büttner, D, Thiemer, B and Sawers, RG (2012) Aconitase B is required for optimal growth of Xanthomonas campestris pv. vesicatoria in pepper plants. PLoS ONE 7:e34941
Abstract	The aerobic plant pathogenic bacterium Xanthomonas campestris pv. vesicatoria (Xcv) colonizes the intercellular spaces of pepper and tomato. One enzyme that might contribute to the successful proliferation of Xcv in the host is the iron-sulfur protein aconitase, which catalyzes the conversion of citrate to isocitrate in the tricarboxylic acid (TCA) cycle and might also sense reactive oxygen species (ROS) and changes in cellular iron levels. Xcv contains three putative aconitases, two of which, acnA and acnB, are encoded by a single chromosomal locus. The focus of this study is aconitase B (AcnB). acnB is co-transcribed with two genes, XCV1925 and XCV1926, encoding putative nucleic acid-binding proteins. In vitro growth of acnB mutants was like wild type, whereas in planta growth and symptom formation in pepper plants were impaired. While acnA, XCV1925 or XCV1926 mutants showed a wild-type phenotype with respect to bacterial growth and in planta symptom formation, proliferation of the acnB mutant in susceptible pepper plants was significantly impaired. Furthermore, the deletion of acnB led to reduced HR induction in resistant pepper plants and an increased susceptibility to the superoxide-generating compound menadione. As AcnB complemented the growth deficiency of an Escherichia coli aconitase mutant, it is likely to be an active aconitase. We therefore propose that optimal growth and survival of Xcv in pepper plants depends on AcnB, which might be required for the utilization of citrate as carbon source and could also help protect the bacterium against oxidative stress.
Links	PubMed PMC3321045 Online version:10.1371/journal.pone.0034941
Keywords	Aconitate Hydratase/chemistry; Aconitate Hydratase/genetics; Aconitate Hydratase/metabolism; Bacterial Proteins/chemistry; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Citric Acid/metabolism; Escherichia coli; Gene Expression; Genetic Complementation Test; Isoenzymes/chemistry; Isoenzymes/genetics; Isoenzymes/metabolism; Lycopersicon esculentum/microbiology; Piper nigrum/microbiology; Plant Diseases/microbiology; Plasmids; Reactive Oxygen Species/metabolism; Sequence Homology, Amino Acid; Transformation, Bacterial; Virulence; Xanthomonas campestris/enzymology; Xanthomonas campestris/genetics; Xanthomonas campestris/pathogenicity
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
DROME:Q9VIE8	Contributes to	GO:0003994: aconitate hydratase activity	ECO:0000314:		F		Found in fruit flies and pathogenic to plants; floats in the cytosol of bacteria.	complete CACAO 10557

References

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