Abstract
The central carbon/lactate utilization pathway in the model sulfate-reducing bacterium, Desulfovibrio vulgaris Hildenborough, is encoded by the highly conserved operon DVU3025-3033. Our earlier in vitro genome-wide study had suggested a network of four two-component system regulators that target this large operon; however, how these four regulators control this operon was not known. Here, we probe the regulation of the lactate utilization operon with mutant strains and DNA-protein binding assays. We show that the LurR response regulator is required for optimal growth and complete lactate utilization, and that it activates the DVU3025-3033 lactate oxidation operon as well as DVU2451, a lactate permease gene, in the presence of lactate. We show by electrophoretic mobility shift assays that LurR binds to three sites in the upstream region of DVU3025, the first gene of the operon. NrfR, a response regulator that is activated under nitrite stress, and LurR share similar binding site motifs and bind the same sites upstream of DVU3025. The DVU3025 promoter also has a binding site motif (Pho box) that is bound by PhoB, a two-component response regulator activated under phosphate limitation. The lactate utilization operon, the regulator LurR, and LurR binding sites are conserved across the order Desulfovibrionales whereas possible modulation of the lactate utilization genes by additional regulators such as NrfR and PhoB appears to be limited to D. vulgaris.
Highlights
Sulfate-reducing bacteria such as Desulfovibrio play an important role in anaerobic microbial communities in groundwater sediments and reduce toxic heavy metals such as chromium (VI) and uranium (VI) in nuclear waste-contaminated sites [1,2]
We show that the LurR regulator strongly activates the lactate permease gene DVU2451 and moderates the central carbon utilization operon DVU3025-3033 in the model sulfate reducer D. vulgaris Hildenborough
Activation by LurR depends on the presence of lactate, since deletion of lurR affected the expression of the lactate utilization operon during growth on lactate-sulfate, but not on pyruvate-sulfate
Summary
Sulfate-reducing bacteria such as Desulfovibrio play an important role in anaerobic microbial communities in groundwater sediments and reduce toxic heavy metals such as chromium (VI) and uranium (VI) in nuclear waste-contaminated sites [1,2]. These bacteria use organic compounds such as lactate, ethanol, and pyruvate as electron donors for the reduction of sulfate [3]. Addition of lactate compounds to contaminated wells can stimulate growth of the anaerobic microbial community and promote heavy metal reduction [4].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
