Exploring the role of CheA3 in Desulfovibrio vulgaris Hildenborough motility

Jayashree Ray,Jarrod J Robertson,Grant M Zane,Lara Rajeev,Aindrila Mukhopadhyay,Marcin Zemla,Thomas R Juba,Michela Catena,Kimberly L Keller,Judy D Wall,Bernhard Knierim,Manfred Auer

doi:10.3389/fmicb.2014.00077

Jayashree Ray, Jarrod J Robertson + Show 10 more

Open Access

https://doi.org/10.3389/fmicb.2014.00077

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Abstract

Sulfate-reducing bacteria such as Desulfovibrio vulgaris Hildenborough are often found in environments with limiting growth nutrients. Using lactate as the electron donor and carbon source, and sulfate as the electron acceptor, wild type D. vulgaris shows motility on soft agar plates. We evaluated this phenotype with mutants resulting from insertional inactivation of genes potentially related to motility. Our study revealed that the cheA3 (DVU2072) kinase mutant was impaired in the ability to form motility halos. Insertions in two other cheA loci did not exhibit a loss in this phenotype. The cheA3 mutant was also non-motile in capillary assays. Complementation with a plasmid-borne copy of cheA3 restores wild type phenotypes. The cheA3 mutant displayed a flagellum as observed by electron microscopy, grew normally in liquid medium, and was motile in wet mounts. In the growth conditions used, the D. vulgaris ΔfliA mutant (DVU3229) for FliA, predicted to regulate flagella-related genes including cheA3, was defective both in flagellum formation and in forming the motility halos. In contrast, a deletion of the flp gene (DVU2116) encoding a pilin-related protein was similar to wild type. We conclude that wild type D. vulgaris forms motility halos on solid media that are mediated by flagella-related mechanisms via the CheA3 kinase. The conditions under which the CheA1 (DVU1594) and CheA2 (DVU1960) kinase function remain to be explored.

Highlights

Desulfovibrio vulgaris Hildenborough is an anaerobic model sulfate-reducing bacterium (SRB), representing the broad class of SRB that play an essential role in biogeochemical processes such as sulfur- and metal-cycling (Zhou et al, 2011)
D. vulgaris displays a single polar flagellum (Postgate and Campbell, 1966) and is documented to have motility on soft agar plates prepared with 0.7% agarose and defined lactate/sulfate medium (Clark et al, 2007), with concentrations not considered limiting for either lactate or sulfate (Postgate, 1963; Mukhopadhyay et al, 2006)
The cheA3 mutant showed a clear defect in this phenotype, whereas the remaining two cheA mutants were unaffected

Summary

Introduction

Desulfovibrio vulgaris Hildenborough is an anaerobic model sulfate-reducing bacterium (SRB), representing the broad class of SRB that play an essential role in biogeochemical processes such as sulfur- and metal-cycling (Zhou et al, 2011). Growth assays of D. vulgaris wild type, JW801, CA023 (cheA1 mutant), CA007 (cheA2 mutant), CA022 (cheA3 mutant), and the cheA3 complemented strain, cheA3::pTOPO-cheA3int(pMO2027). To obtain a complemented cheA3 mutant, cheA3 cells (CA022) were transformed with pMO2027 by electroporation as described (Keller et al, 2009), with the following exceptions: MOYLS4 (60/30, lactate/sulfate) medium was used throughout growth, electroporation, recovery and selective plating of the Frontiers in Microbiology | Microbial Physiology and Metabolism

Results

Conclusion