Abstract:
:Two-component regulatory systems play an important role in bacterial virulence. We report that mutation of a Pseudomonas aeruginosa gene designated retS (previously designated fimK; accession number PA4856) encoding a putative hybrid two-component regulator, attenuates multiple virulence mechanisms. The retS mutant was selected from a Tn5 transposon library of the cytotoxic P. aeruginosa strain PA103 based upon expression of a small-colony phenotype suggestive of reduced surface-associated "twitching" motility, a property dependent upon type IV pili. Subsequent analysis revealed that the mutant expressed pilin, albeit at lower levels than wild-type PA103. In a murine model of corneal infection, retS mutation was associated with delayed disease development and altered pathology. In vitro, retS mutants demonstrated loss of acute cytotoxic activity towards corneal epithelia as determined by trypan blue exclusion and by LDH release assays (P<0.0001). This coincided with loss of ExsA-regulated type III secretion. Mutation of retS also impaired ExsA-independent pathogenic mechanisms. When compared to the exsA mutant of PA103, retS mutants exhibited reduced epithelial adherence and invasion and reduced intracellular survival within the cells after invasion. Time-lapse video microscopy revealed that retS mutants, compared to exsA mutants, had a reduced capacity to access, and move along, the basal cell surfaces of corneal epithelial cell monolayers. Taken together, these data suggest that the protein encoded by retS regulates various properties of P. aeruginosa including both ExsA-dependent and ExsA-independent virulence mechanisms.
journal_name
Microbes Infectjournal_title
Microbes and infectionauthors
Zolfaghar I,Angus AA,Kang PJ,To A,Evans DJ,Fleiszig SMdoi
10.1016/j.micinf.2005.04.017subject
Has Abstractpub_date
2005-10-01 00:00:00pages
1305-16issue
13eissn
1286-4579issn
1769-714Xpii
S1286-4579(05)00180-2journal_volume
7pub_type
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