title: Cystalysin, a 46-kDa L-cysteine desulfhydrase from Treponema denticola: biochemical and biophysical characterization.
abstract: A 46-kDa hemolytic protein referred to as cystalysin, from Treponema denticola ATCC 35404, was characterized and overexpressed in Escherichia coli LC-67. Cystalysin lysed erythrocytes, hemoxidized hemoglobin to sulfhemoglobin and methemoglobin, and removed the sulfhydryl and amino group from selected S-containing compounds (e.g., cysteine) producing H2S, NH3, and pyruvate. With L-cysteine as substrate, cystalysin obeys Michaelis-Menten kinetics. Cystathionine and s-aminoethyl-L-cysteine were also substrates. Several of the small alpha amino acids were found to be competitive inhibitors of cystalysin. The enzymatic activity was increased by beta-mercaptoethanol and was not inhibited by the proteinase inhibitor TLCK (N alpha-p-tosyl-L-lysine chloromethyl ketone), pronase, or proteinase K, suggesting the functional site was physically protected or located in a small fragment of the polypeptide. We hypothesize that cystalysin is a pyridoxal-5-phosphate-containing enzyme with the activity of an alphaC-N and betaC-S lyase (cystathionase). Since high amounts of H2S have been reported in deep periodontal pockets, this metabolic enzyme from T. denticola may also function in vivo as an important virulence molecule.
authors: Department of Microbiology, University of Texas Health Science Center at San Antonio, 78284-7758, USA.
authors: L
authors: L
authors: Chu
authors: J L
authors: JL
authors: Ebersole
authors: G P
authors: GP
authors: Kurzban
authors: S C
authors: SC
authors: Holt
mesh_terms: D003542:Cystathionine gamma-Lyase / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004912:Erythrocytes / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D006461:Hemolysis; D007700:Kinetics; D010084:Oxidation-Reduction; D011994:Recombinant Proteins / Q000378:metabolism; D013379:Substrate Specificity; D014208:Treponema / Q000201:enzymology* / Q000235:genetics
chemical_list: D004791:Enzyme Inhibitors; D011994:Recombinant Proteins; D003542:Cystathionine gamma-Lyase