Shewanella oneidensisHfq promotes exponential phase growth, stationary phase culture density, and cell survival

Christopher M Brennan,Matthew T Goulet,Brett J Pellock,Katherine E Douglas,Jessica M Osborn,Zachary Sexton,Nicholas Q Mazzucca,Taylor Mezoian,Meghan L Keane,Taylor M Hunt

doi:10.1186/1471-2180-13-33

Christopher M Brennan, Matthew T Goulet + Show 8 more

Open Access

https://doi.org/10.1186/1471-2180-13-33

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Journal: BMC microbiology	Publication Date: Feb 8, 2013
Citations: 39	License type: cc-by

Affiliation: Providence College

Abstract

BackgroundHfq is an RNA chaperone protein that has been broadly implicated in sRNA function in bacteria. Here we describe the construction and characterization of a null allele of the gene that encodes the RNA chaperone Hfq in Shewanella oneidensis strain MR-1, a dissimilatory metal reducing bacterium.ResultsLoss of hfq in S. oneidensis results in a variety of mutant phenotypes, all of which are fully complemented by addition of a plasmid-borne copy of the wild type hfq gene. Aerobic cultures of the hfq∆ mutant grow more slowly through exponential phase than wild type cultures, and hfq∆ cultures reach a terminal cell density in stationary phase that is ~2/3 of that observed in wild type cultures. We have observed a similar growth phenotype when the hfq∆ mutant is cultured under anaerobic conditions with fumarate as the terminal electron acceptor, and we have found that the hfq∆ mutant is defective in Cr(VI) reduction. Finally, the hfq∆ mutant exhibits a striking loss of colony forming units in extended stationary phase and is highly sensitive to oxidative stress induced by H2O2 or methyl viologen (paraquat).ConclusionsThe hfq mutant in S. oneidensis exhibits pleiotropic phenotypes, including a defect in metal reduction. Our results also suggest that hfq mutant phenotypes in S. oneidensis may be at least partially due to increased sensitivity to oxidative stress.

Highlights

Hfq is an RNA chaperone protein that has been broadly implicated in sRNA function in bacteria
Antibiotics were used at the following concentrations: Gentamicin (Gm): 5 μg/ml; Tetracycline (Tc): 10 μg/ml for E. coli; 1 μg/ml for S. oneidensis, [we used a lower concentration of Tc for selection of S. oneidensis than for E. coli because we found that the minimum inhibitory concentration (MIC) of Tc for S. oneidensis MR-1 is
Construction and verification of a null allele of hfq in Shewanella oneidensis MR-1 To study the roles played by the hfq gene in Shewanella oneidensis, we constructed a null allele of the putative hfq gene (So_0603) in S. oneidensis strain MR-1 [9,12]

Summary

Introduction

Hfq is an RNA chaperone protein that has been broadly implicated in sRNA function in bacteria. Hfq is an RNA chaperone broadly implicated in sRNA function in many bacteria. A common hfq mutant phenotype is slow growth through exponential phase. Loss of hfq function usually results in an array of mutant phenotypes, many of which are bacterium-specific. E. coli hfq mutants exhibit slow growth in vitro [5], survive poorly in stationary phase, and are sensitive to both H2O2 and hyperosmotic conditions [8]. Hfq mutants in Vibrio cholerae grow reasonably well in vitro (though they exhibit impaired growth in a mouse infection model), survive normally in stationary phase, and are fully resistant to both H2O2 and hyperosmotic conditions [7]. The fact that hfq mutations in different bacteria produce distinct phenotypes suggests distinct evolutionary roles for both Hfq and sRNAs in these divergent bacteria

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