Re-evaluation of a Tn5::gacA mutant of Pseudomonas syringae pv. tomato DC3000 uncovers roles for uvrC and anmK in promoting virulence

Autoři: Megan R. O’Malley aff001;  Alexandra J. Weisberg aff001;  Jeff H. Chang aff001;  Jeffrey C. Anderson aff001
Působiště autorů: Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, United States of America aff001;  Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon, United States of America aff002
Vyšlo v časopise: PLoS ONE 14(10)
Kategorie: Research Article
doi: 10.1371/journal.pone.0223637


Pseudomonas syringae is a taxon of plant pathogenic bacteria that can colonize and proliferate within the interior space of leaf tissue. This process requires P. syringae to rapidly upregulate the production of virulence factors including a type III secretion system (T3SS) that suppress host defenses. GacS/A is a two-component system that regulates virulence of many plant and animal pathogenic bacteria including P. syringae. We recently investigated the virulence defect of strain AC811, a Tn5::gacA mutant of P. syringae pv. tomato DC3000 that is less virulent on Arabidopsis. We discovered that decreased virulence of AC811 is not caused by loss of GacA function. Here, we report the molecular basis of the virulence defect of AC811. We show that AC811 possesses a nonsense mutation in anmK, a gene predicted to encode a 1,6-anhydromuramic acid kinase involved in cell wall recycling. Expression of a wild-type allele of anmK partially increased growth of AC811 in Arabidopsis leaves. In addition to the defective anmK allele, we also show that the Tn5 insertion in gacA exerts a polar effect on uvrC, a downstream gene encoding a regulator of DNA damage repair. Expression of the wild-type anmK allele together with increased expression of uvrC fully restored the virulence of AC811 during infection of Arabidopsis. These results demonstrate that defects in anmK and uvrC are together sufficient to account for the decreased virulence of AC811, and suggest caution is warranted in assigning phenotypes to GacA function based on insertional mutagenesis of the gacA-uvrC locus.

Klíčová slova:

Arabidopsis thaliana – Leaves – Nonsense mutation – Plant bacterial pathogens – Polymerase chain reaction – Virulence factors – Pseudomonas syringae – Apoplastic space


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