RT Journal Article
SR Electronic
T1 Genomic and gene-expression comparisons among phage-resistant type-IV pilus mutants of <em>Pseudomonas syringae</em> pathovar <em>phaseolicola</em>
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 025106
DO 10.1101/025106
A1 Mark Sistrom
A1 Derek Park
A1 Heath E. O’Brien
A1 Zheng Wang
A1 David S. Guttman
A1 Jeffrey P. Townsend
A1 Paul E. Turner
YR 2015
UL http://biorxiv.org/content/early/2015/08/20/025106.abstract
AB Pseudomonas syringae pv. phaseolicola (Pph) is a significant bacterial pathogen of agricultural crops, and phage ϕ6 and other members of the dsRNA virus family Cystoviridae undergo lytic (virulent) infection of Pph, using the type IV pilus as the initial site of cellular attachment. Despite the popularity of Pph/phage ϕ6 as a model system in evolutionary biology, Pph resistance to phage ϕ6 remains poorly characterized. To investigate differences between phage ϕ6 resistant Pph strains, we examined genomic and gene expression variation among three bacterial genotypes that differ in the number of type IV pili expressed per cell: ordinary (wild-type), non-piliated, and super-piliated. Genome sequencing of non-piliated and super-piliated Pph identified few mutations that separate these genotypes from wild type Pph – and none present in genes known to be directly involved in type IV pilus expression. Expression analysis revealed that 81.1% of GO terms up-regulated in the non-piliated strain were down-regulated in the super-piliated strain. This differential expression is particularly prevalent in genes associated with respiration — specifically genes in the tricarboxylic acid cycle (TCA) cycle, aerobic respiration, and acetyl-CoA metabolism. The expression patterns of the TCA pathway appear to be generally up and down-regulated, in non-piliated and super-piliated Pph respectively. As pilus retraction is mediated by an ATP motor, loss of retraction ability might lead to a lower energy draw on the bacterial cell, leading to a different energy balance than wild type. The lower metabolic rate of the super-piliated strain is potentially a result of its loss of ability to retract.