A Putative ABC Transporter, HatABCDE, Is among Molecular Determinants of Pyomelanin Production inPseudomonas aeruginosa

Abstract

Pyomelanin overproduction is a common phenotype among Pseudomonas aeruginosa isolates recovered from cystic fibrosis and urinary tract infections. Its prevalence suggests that it contributes to the persistence of the producing microbial community, yet little is known about the mechanisms of its production. Using transposon mutagenesis, we identified factors that contribute to melanogenesis in a clinical isolate of P. aeruginosa. In addition to two enzymes already known to be involved in its biosynthesis (homogentisate dioxygenase and hydroxyphenylpyruvate dioxygenase), we identified 26 genes that encode regulatory, metabolic, transport, and hypothetical proteins that contribute to the production of homogentisic acid (HGA), the monomeric precursor of pyomelanin. One of these, PA14_57880, was independently identified four times and is predicted to encode the ATP-binding cassette of an ABC transporter homologous to proteins in Pseudomonas putida responsible for the extrusion of organic solvents from the cytosol. Quantification of HGA production by P. aeruginosa PA14 strains missing the predicted subcomponents of this transporter confirmed its role in HGA production: mutants unable to produce the ATP-binding cassette (PA14_57880) or the permease (PA14_57870) produced substantially less extracellular HGA after growth for 20 h than the parental strain. In these mutants, concurrent accumulation of intracellular HGA was observed. In addition, quantitative real-time PCR revealed that intracellular accumulation of HGA elicits upregulation of these transport genes. Based on their involvement in homogentisic acid transport, we rename the genes of this operon hatABCDE.

A PhoPQ-Regulated ABC Transporter System Exports Tetracycline in Pseudomonas aeruginosa

“…In some antibiotic-producing or drug-resistant bacteria, ABC systems are responsible for the efflux of antibiotics (23,24). In P. aeruginosa, ABC systems are key participants in many process, such as siderophore synthesis or transfer (25), lipopolysaccharide secretion (26), the acquisition of heme and hemoglobin (27), orthophosphate uptake (28), homogentisic acid transport (29), and the acquisition of zinc (30). In contrast to the many RND efflux pumps, ABC systems associated with antibiotic susceptibility are less common in P. aeruginosa.…”

Molecular Epidemiology of Beta-Lactamases in Ceftazidime-Resistant Pseudomonas aeruginosa Isolates

“…Çalışmamızda, izolatların %57.9'unda (113/195) GES pozitifl iği saptanmış; ancak dizi analizi sonucunda 113 izolatın 26'sının GES-1 GSBL geni, 87 izolatın ise aynı primer dizileri ile saptanan ABC taşıyıcı permeaz geni taşıdığı gösterilmiştir. Bu proteinin siderofor özellik gösteren pigment üretiminden sorumlu olduğu, dışa atım pompa sistemi aracılığıyla antibiyotik direncine neden olabileceği ve bakterinin virülans faktörleri ile ilişkili olduğu düşünülmektedir 31 . Tüm bu veriler GES enzimlerinin ülkemizde de yaygın olabileceğini düşündürmektedir.…”

Pigments influence the tolerance of Pseudomonas aeruginosa PAO1 to photodynamically induced oxidative stress

“…The observed tolerance to singlet oxygen of pyomelanin emphasizes its role as a virulence factor in a clinical background. Indeed pyomelanin production has been reported in P. aeruginosa isolates from chronically infected cystic fibrosis patients (Hunter & Newman, 2010), so the observed tolerance to singlet oxygen stress could contribute to their surviving in alveolar areas where macrophages and neutrophils generate both radicals and singlet oxygen (du Bois, 1985).…”