Analogies and surprising differences between recombinant nitric oxide synthase-like proteins from Staphylococcus aureus and Bacillus anthracis in their interactions with l-arginine analogs and iron ligands.
Genome sequencing has recently shown the presence of genes coding for NO-synthase (NOS)-like proteins in bacteria. The roles of these proteins remain unclear. The interactions of a series of l-arginine (l-arg) analogs and iron ligands with two recombinant NOS-like proteins from Staphylococcus aureus (saNOS) and Bacillus anthracis (baNOS) have been studied by UV-visible spectroscopy. SaNOS and baNOS in their ferric native state, as well as their complexes with l-arg analogs and with various ligands, exhibit spectral characteristics highly similar to the corresponding complexes of heme-thiolate proteins such as cytochromes P450 and NOSs. However, saNOS greatly differs from baNOS at the level of three main properties: (i) native saNOS mainly exists under an hexacoordinated low-spin ferric state whereas native baNOS is mainly high-spin, (ii) the addition of tetrahydrobiopterin (H4B) or H4B analogs leads to an increase of the affinity of l-arg for saNOS but not for baNOS, and (iii) saNOS Fe(II), contrary to baNOS, binds relatively bulky ligands such as nitrosoalkanes and tert-butylisocyanide. Thus, saNOS exhibits properties very similar to those of the oxygenase domain of inducible NOS (iNOS(oxy)) not containing H4B, as expected for a NOSoxy-like protein that does not contain H4B. By contrast, the properties of baNOS which look like those of H4B-containing iNOS(oxy) are unexpected for a NOS-like protein not containing H4B. The origin of these surprising properties of baNOS remains to be determined.
Salard
Isabelle
I
Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, Université R. Descartes Paris 5, UMR 8601 CNRS, 45 rue des Saints Pères, 75270 Paris cedex 06, France.
Mercey
Emilie
E
Rekka
Eleni
E
Boucher
Jean-Luc
JL
Nioche
Pierre
P
Mikula
Ivan
I
Martasek
Pavel
P
Raman
C S
CS
Mansuy
Daniel
D
D001120:Arginine / Q000378:metabolism*; D001408:Bacillus anthracis / Q000201:enzymology*; D007501:Iron / Q000378:metabolism*; D008024:Ligands; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet; D013211:Staphylococcus aureus / Q000201:enzymology*
D008024:Ligands; D011994:Recombinant Proteins; D001120:Arginine; D007501:Iron; D019001:Nitric Oxide Synthase