Dr. Al Claiborne
Professor of Biochemistry
B.A., Vanderbilt University, 1974
Ph.D. (Biochemistry), Duke University, 1979
Telephone: (336) 716-3914
Electronic mail: alc@csb.wfu.edu
Gram-positive bacteria such as the streptococci present an intriguing system for investigating the structural, functional, and genetic aspects of oxygen metabolism. These facultative anaerobes lack the ability to synthesize heme and therefore do not have either catalase or the respiratory cytochromes found in other bacteria such as Escherichia coli. In place of these hemeproteins, streptococci have developed an unusual array of flavin-linked enzymatic responses to the presence of oxygen and its metabolites; these include the NADH peroxidase and NADH oxidase, which have been studied intensively in our laboratory. The combined application of molecular cloning approaches with X-ray crystallography and functional analyses has allowed us to demonstrate that these proteins represent a new class of peroxide reductases within the flavoprotein disulfide reductase family. A major distinction between the peroxide and disulfide reductase classes lies in the unique cysteine-sulfenic acid (Cys-SOH) redox center identified in the peroxidase and oxidase, in contrast to the redox-active disulfides (Cys-SS-Cys) found in most disulfide reductases. Our laboratory is currently applying technologies spanning the range from site-directed mutagenesis to rapid reaction kinetics and crystallography in the study of the peroxidase and oxidase. In connection with these studies, we are also investigating the unique coenzyme A-disulfide reductase from Staphylococcus aureus and the streptococcal alpha-glycerophosphate oxidase.
Recent publications:
Crane EJ 3rd, Yeh JI, Luba J, Claiborne A.: Analysis of the kinetic and redox properties of the NADH peroxidase R303M mutant: correlation with the crystal structure. Biochemistry 39: 10353-10364 (2000).
Charrier V, Luba J, Parsonage D, Claiborne A.: Limited proteolysis as a structural probe of the soluble alpha-glycerophosphate oxidase from Streptococcus sp. Biochemistry 39: 5035-5044 (2000).
Ward DE, van Der Weijden CC, van Der Merwe MJ, Westerhoff HV, Claiborne A, Snoep JL.: Branched-chain alpha-keto acid catabolism via the gene products of the bkd operon in Enterococcus faecalis: a new, secreted metabolite serving as a temporary redox sink. J. Bacteriol 182: 3239-3246 (2000).
Gibson CM, Mallett TC, Claiborne A. Caparon MG.: Contribution of NADH oxidase to aerobic metabolism of Streptococcus pyogenes. J. Bacteriol 182: 448-455 (2000).
Claiborne A, Yeh JI, Mallett TC, Luba J, Crane EJ 3rd, Charrier V, Parsonage D.: Protein-sulfenic acids: diverse roles for an unlikely player in enzyme catalysis and redox regulation. Biochemistry 38: 15407-15416 (1999).
Ward DE, Ross RP, van der Weijden CC, Snoep JL, Claiborne A Catabolism of branched-chain alpha-keto acids in Enterococcus faecalis: the bkd gene cluster, enzymes, and metabolic route. J. Bacteriol. 181: 5433-5442 (1999).
Mallett, T.C., Parsonage, D., Claiborne, A.: Equilibrium analyses of the active-site asymmetry in enterococcal NADH oxidase: role of the cysteine-sulfenic acid redox center. Biochemistry 38:3000-3011 (1999).
Luba, J., Charrier, V., Claiborne, A.: Coenzyme A-disulfide reductase from Staphylococcus aureus: evidence for asymmetric behavior on interaction with pyridine nucleotides. Biochemistry 38:2725-2737 (1999).
Parsonage, D., Luba, J., Mallett, T.C., Claiborne, A.: The soluble alpha-glycerophosphate oxidase from Enterococcus casseliflavus. Sequence homology with the membrane-associated dehydrogenase and kinetic analysis of the recombinant enzyme. J. Biol. Chem. 273:23812-23822 (1998).
Mallett, T.C., Claiborne, A.: Oxygen reactivity of an NADH oxidase C42S mutant: evidence for a C(4a)-peroxyflavin intermediate and a rate-limiting conformational change. Biochemistry 37:8790-8802 (1998).
Stereo view of the superimposed active sites of the C44S mutant of Streptococcus pyogenes NADH oxidase (Nox; Mallett TC, Sakai H, Parsonage D, Claiborne A, and Tsukihara T) and the wild-type NA DH peroxidase (Npx; Yeh JI, Parsonage D, and Claiborne A).