Characterization of a butyrate kinase from Desulfovibrio vulgaris str. Hildenborough

Abstract

Sulfate‐reducing bacteria play a key role in the global carbon and sulfur cycles; a role realized through complex competitive or syntrophic metabolic relationships. These relationships are established in response to sulfate levels as well as concentrations of other nutrients such as short chain fatty acids (SCFAs). For some prokaryotes, SCFA production or consumption requires an ATP‐dependent reaction catalyzed by a SCFA kinase. In this study, we have determined the biochemical properties of a butyrate kinase from Desulfovibrio vulgaris str. Hildenborough heterologously expressed in E. coli. Our experiments characterize optimal conditions for activity as well as kinetic parameters for six SCFA substrates and the nucleotide cofactor ATP. These findings have implications on structure and function relationships as well as the potential physiological role of this enzyme.Support or Funding InformationThe authors would like to thank the Scott and Alice Thomson Fellowship Program for financial support of MB. Further, the authors thank the UW‐Parkside Committee on Research and Creative Activity and the College of Natural and Health Sciences for financial support of this project.Enzymatic Characterization of DvBuk.(A) DvBuk purity assessment was visualized by resolving 10 μg of purified DvBuk on 10% (w/v) polyacrylamide gel and stained with Coomassie Blue. Lane 1: Protein molecular weight markers, Lane 2: recombinant His‐tagged DvBuk. Enzyme activity (%) at various (B) pH and (C) temperature values. (D) Saturation kinetics of DvBuk with butyrate as substrate. (E) Relative activities of DvBuk in the presence of various SCFA substrates.Figure 1Substrate Preference of DvBuk.(A) Relative activities of DvBuk in the presence of various SCFA substrates (relative activities normalized to observed specific activity in the presence of 200 mM valerate = 9.7 U mg−1). (B) Kinetic constants for DvBuk using various SCFA substrates.Figure 2