title: DcrA, a c-type heme-containing methyl-accepting protein from Desulfovibrio vulgaris Hildenborough, senses the oxygen concentration or redox potential of the environment.
abstract: The amino acid sequence of DcrA from Desulfovibrio vulgaris Hildenborough, a strictly anaerobic, sulfate-reducing bacterium, indicated homology with the methyl-accepting chemotaxis proteins from enteric bacteria (A. Dolla, R. Fu, M. J. Brumlik, and G. Voordouw, J. Bacteriol. 174:1726-1733, 1992). The homology is restricted to the cytoplasmic C-terminal signaling domain. The periplasmic N-terminal sensor domain was found to contain a unique sequence, CHHCH, corresponding to a consensus c-type heme binding site. A pretreated, DcrA-specific polyclonal antiserum, generated against DcrA protein overproduced in Escherichia coli, was used for immunoprecipitation of 35S-labeled DcrA from D. vulgaris and Desulfovibrio desulfuricans G200(pJRFR2), a transconjugant that overexpresses functional DcrA. Labeling of the latter with the heme precursor 5-amino-[4-14C]levulinic acid, followed by immunoprecipitation, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and fluorography, confirmed the presence of c-type heme, while labeling with L-[methyl-3H]methionine in the absence of protein synthesis confirmed that DcrA is a methyl-accepting protein. The base liability of the incorporated radioactivity indicated methyl ester formation like that occurring in the methyl-accepting chemotaxis proteins of enteric bacteria. L-[methyl-3H]methionine labeling of D. desulfuricans G200(pJRFR2) under different conditions indicated that methyl labeling of DcrA decreased upon addition of oxygen and increased upon subsequent addition of the reducing agent dithionite. These results indicate that DcrA may serve as a sensor of oxygen concentration and/or redox potential.
authors.affiliation: Department of Biological Sciences, University of Calgary, Alberta, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Fu
authors.forename: J D
authors.initials: JD
authors.lastname: Wall
authors.forename: G
authors.initials: G
authors.lastname: Voordouw
mesh_terms: D000595:Amino Acid Sequence; D000907:Antibodies, Bacterial; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D003901:Desulfovibrio / Q000378:metabolism; D016969:Desulfovibrio vulgaris / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D004227:Dithionite / Q000494:pharmacology; D006418:Heme / Q000302:isolation & purification; D007553:Isotope Labeling; D008565:Membrane Proteins / Q000378:metabolism; D000072236:Methyl-Accepting Chemotaxis Proteins; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010100:Oxygen / Q000494:pharmacology*; D011233:Precipitin Tests; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D015398:Signal Transduction
chemical_list: D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; D011993:Recombinant Fusion Proteins; C085429:dcrA protein, Desulfovibrio vulgaris; D004227:Dithionite; D006418:Heme; D010100:Oxygen