Dataset Information

PBP1a/LpoA but not PBP1b/LpoB are involved in regulation of the major ?-lactamase gene blaA in Shewanella oneidensis.

ABSTRACT: ?-Lactamase production is one of the most important strategies for Gram-negative bacteria to combat ?-lactam antibiotics. Studies of the regulation of ?-lactamase expression have largely been focused on the class C ?-lactamase AmpC, whose induction by ?-lactams requires LysR-type regulator AmpR and permease AmpG-dependent peptidoglycan recycling intermediates. In Shewanella, which is ubiquitous in aquatic environments and is a reservoir for antibiotic resistance, production of the class D ?-lactamase BlaA confers bacteria with natural resistance to many ?-lactams. Expression of the blaA gene in the genus representative Shewanella oneidensis is distinct from the AmpC paradigm because of the lack of an AmpR homologue and the presence of an additional AmpG-independent regulatory pathway. In this study, using transposon mutagenesis, we identify proteins that are involved in blaA regulation. Inactivation of mrcA and lpoA, which encode penicillin binding protein 1a (PBP1a) and its lipoprotein cofactor, LpoA, respectively, drastically enhances blaA expression in the absence of ?-lactams. Although PBP1b and its cognate, LpoB, also exist in S. oneidensis, their roles in blaA induction are dispensable. We further show that the mrcA-mediated blaA expression is independent of AmpG.

SUBMITTER: Yin J

PROVIDER: S-EPMC4432149 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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PBP1a/LpoA but not PBP1b/LpoB are involved in regulation of the major β-lactamase gene blaA in Shewanella oneidensis.

Yin Jianhua J Sun Yiyang Y Mao Yinting Y Jin Miao M Gao Haichun H

Antimicrobial agents and chemotherapy 20150330 6

β-Lactamase production is one of the most important strategies for Gram-negative bacteria to combat β-lactam antibiotics. Studies of the regulation of β-lactamase expression have largely been focused on the class C β-lactamase AmpC, whose induction by β-lactams requires LysR-type regulator AmpR and permease AmpG-dependent peptidoglycan recycling intermediates. In Shewanella, which is ubiquitous in aquatic environments and is a reservoir for antibiotic resistance, production of the class D β-lact ...[more]

PMID: 25824223

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Project description:Although little is known of potential function for conserved signaling proteins, it is hypothesized that such proteins play important roles to coordinate cellular responses to environmental stimuli. In order to elucidate the function of a putative sensory box protein (PAS domains) in Shewanella oneidensis MR-1, the physiological role of SO3389 was characterized. The predicted open reading frame (ORF) encodes a putative sensory box protein that has PAS, GGDEF, and EAL domains, and an in-frame deletion mutant was constructed (?SO3389) with approximately 95% of the ORF deleted. Under aerated conditions, wild-type and mutant cultures had similar growth rates, but the mutant culture had a lower growth rate under static, aerobic conditions. Oxygen consumption rates were lower for mutant cultures (1.5-fold), and wild-type cultures also maintained lower dissolved oxygen concentrations under aerated growth conditions. When transferred to anoxic conditions, the mutant did not grow with fumarate, iron(III), or dimethyl sulfoxide (DMSO) as electron acceptors. Biochemical assays demonstrated the expression of different c-type cytochromes as well as decreased fumarate reductase activity in the mutant transferred to anoxic growth conditions. Transcriptomic studies showed the inability of the mutant to up-express and down-express genes, including c-type cytochromes (e.g., SO4047/SO4048, SO3285/SO3286), reductases (e.g., SO0768, SO1427), and potential regulators (e.g., SO1329). The complemented strain was able to grow when transferred from aerobic to anoxic growth conditions with the tested electron acceptors. The modeled structure for the SO3389 PAS domains was highly similar to the crystal structures of FAD-binding PAS domains that are known O2/redox sensors. Based on physiological, genomic, and bioinformatic results, we suggest that the sensory box protein, SO3389, is an O2/redox sensor that is involved in optimization of aerobic growth and transitions to anoxia in S. oneidensis MR-1.

Dataset Information

PBP1a/LpoA but not PBP1b/LpoB are involved in regulation of the major ?-lactamase gene blaA in Shewanella oneidensis.

Publications

PBP1a/LpoA but not PBP1b/LpoB are involved in regulation of the major β-lactamase gene blaA in Shewanella oneidensis.

Similar Datasets

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