Characterization of a novel gene related to antibiotic susceptibility in Pseudomonas aeruginosa

Abstract

Pseudomonas aeruginosa is a human pathogen with increased intrinsic resistance to a large number of antibiotics used in clinical therapy. Therefore, understanding the mechanisms of resistance and developing therapy alternatives for P. aeruginosa are of profound importance. Previous work from our laboratory demonstrated that several mutants have isolated with altered expression of the phzA1B1C1D1E1F1G1 (phzA1) operon in the presence of sub-inhibitory concentrations (SICs) of tetracycline (TET). The present study investigates the roles of the PA0011 gene in mediating phzA1 expression at SIC of TET. The PA0011 gene encodes 2-OH-lauroytransferase by controlling the synthesis of the cell envelope and the outer membrane. We found that the PA0011 mutant strain was susceptible to several different antibiotics and environmental stresses. Complementation in the PA0011 mutant restored these phenotypes to wild-type levels. In addition, expression of the PA0011 gene, as monitored through a luciferase reporter, is increased at SICs of antibiotics. Indeed, the expression of the PA0011 gene increased about threefold in pqsR and pqsH mutants compared with the wild-type PAO1. However, the PA0011 gene negatively regulates the quorum sensing (QS) system. Taken together, these data suggest that PA0011 is involved in susceptibility to antimicrobial agents in P. aeruginosa, and that its susceptibility effect maybe partly dependent on increased QS expression.

Increased ParB level affects expression of stress response, adaptation and virulence operons and potentiates repression of promoters adjacent to the high affinity binding sites parS3 and parS4 in Pseudomonas aeruginosa

“…The product of PA0011 , the 2-OH-lauroyltransferase HtrB1 is involved in lipid A biosynthesis important for integrity of the outer membrane and cell envelope [76–78]. htrB1 expression is induced by sub-inhibitory concentrations of different antibiotics [78] or growth at low temperature [77].…”

“…htrB1 expression is induced by sub-inhibitory concentrations of different antibiotics [78] or growth at low temperature [77]. Inactivation of htrB1 leads to pleiotropic effects, manifested by increased susceptibility to surfactants and antibiotics, impaired swarming motility, growth defects and induction of type III secretion system.…”

Genes Required for and Effects of Alginate Overproduction Induced by Growth of Pseudomonas aeruginosa on Pseudomonas Isolation Agar Supplemented with Ammonium Metavanadate

“…HtrB, a P. aeruginosa orthologue of E. coli LpxL, is an inner membrane acyltransferase responsible for transferring a lauryl group to the lipid A precursor (33); however, P. aeruginosa fatty acylation of lipid A differs from that of E. coli in that the sequence of enzymatic events is not the same (34). A recent study suggests that PA0011 is involved in antibiotic resistance mechanisms (35). In the abovementioned study, PA0011 was shown to be regulated by quorum sensing (QS), and PA0011 mutants were susceptible to various antibiotics and environmental stresses.…”

Increased ParB level affects expression of stress response, adaptation and virulence operons and potentiates repression of promoters adjacent to the high affinity binding sitesparS3andparS4inPseudomonas aeruginosa

“…The product of PA0011 , the 2-OH-lauroyltransferase HtrB1 is involved in lipid A biosynthesis important for integrity of the outer membrane and cell envelope [76–78]. htrB1 expression is induced by sub-inhibitory concentrations of different antibiotics [78] or growth at low temperature [77]. Inactivation of htrB1 leads to pleiotropic effects, manifested by increased susceptibility to surfactants and antibiotics, impaired swarming motility, growth defects and induction of type III secretion system.…”