Detection of a nitric oxide synthase possibly involved in the regulation of the Rhodococcus sp R312 nitrile hydratase.
Crude homogenates from Rhodococcus sp 312 catalyze the conversion of L-arginine into L-citrulline and NO2-, the usual oxidation product of NO under aerobic conditions. They also catalyze the conversion of N omega-hydroxy-L-arginine (NOHA) into L-citrulline and NO2- with similar rates (10-15 and 100-150 nmol of product.min-1.(mg of protein)-1 respectively for the crude homogenate and for a fraction obtained from ammonium sulfate precipitation). L-citrulline formation is strongly inhibited by classical inhibitors of mammalian nitric oxide synthases (NOSs) such as N omega-methyl-L-arginine (NMA) and thio-L-citrulline (TC). Finally, the lack of inhibitory effects of EGTA, a classical inhibitor of constitutive mammalian NOSs, and the specific immunodetection of a 100 kD protein from Rhodococcus cytosol by an antibody raised against human inducible NOS, is in favor of the presence of a NOS similar to inducible mammalian NOSs in Rhodococcus sp 312. This NOS should be responsible for the NO-dependent inactivation of Rhodococcus Nitrile Hydratase (NHase) in the absence of light; it could regulate the activity of the latter enzyme.
Sari
M A
MA
Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques (URA 400 CNRS), Université René Descartes Paris V, France. sari@bisance.citi2.fr
Moali
C
C
Boucher
J L
JL
Jaouen
M
M
Mansuy
D
D
D001426:Bacterial Proteins / Q000378:metabolism; D004789:Enzyme Activation; D006801:Humans; D006836:Hydro-Lyases / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D012240:Rhodococcus / Q000201:enzymology*
D001426:Bacterial Proteins; D019001:Nitric Oxide Synthase; D006836:Hydro-Lyases; C048831:nitrile hydratase