title: Interaction of soluble guanylate cyclase with YC-1: kinetic and resonance Raman studies.
abstract: The enzyme-soluble guanylate cyclase (sGC), which converts GTP to cGMP, is a receptor for the signaling agent nitric oxide (NO). YC-1, a synthetic benzylindazole derivative, has been shown to activate sGC in an NO-independent fashion. In the presence of carbon monoxide (CO), which by itself activates sGC approximately 5-fold, YC-1 activates sGC to a level comparable to stimulation by NO alone. We have used kinetic analyses and resonance Raman spectroscopy (RR) to investigate the interaction of YC-1 and CO with guanylate cyclase. In the presence of CO and 200 microM YC-1, the V(max)/K(m GTP) increases 226-fold. While YC-1 does not perturb the RR spectrum of the ferrous form of baculovirus/Sf9 cell expressed sGC, it induces a shift in the Fe-CO stretching frequency for the CO-bound form from 474 to 492 cm(-1). Similarly, YC-1 has no effect on the RR spectrum of ferrous beta1(1-385), the isolated sGC heme-binding domain, but shifts the nu(Fe-CO) of CO-beta1(1-385) from 478 to 491 cm(-1), indicating that YC-1 binds in heme-binding region of sGC. In addition, the CO-bound forms of sGC and beta1(1-385) in the presence of YC-1 lie on the nu(Fe-CO) vs nu(C-O) correlation curve for proximal ligands with imidazole character, which suggests that histidine remains the heme proximal ligand in the presence of YC-1. Interestingly, YC-1 does not shift nu(Fe-CO) for the CO-bound form of H105G(Im), the imidazole-rescued heme ligand mutant of beta1(1-385). The data are consistent with binding of CO and YC-1 to the sGC heme-binding domain leading to conformational changes that give rise to an increase in catalytic turnover and a change in the electrostatic environment of the heme pocket.
authors.affiliation: Department of Biological Chemistry, Medical School, Howard Hughes Medical Institute, College of Pharmacy, University of Michigan, Ann Arbor, Michigan 48109-0606, USA.
authors.forename: J W
authors.initials: JW
authors.lastname: Denninger
authors.forename: J P
authors.initials: JP
authors.lastname: Schelvis
authors.forename: P E
authors.initials: PE
authors.lastname: Brandish
authors.forename: Y
authors.initials: Y
authors.lastname: Zhao
authors.forename: G T
authors.initials: GT
authors.lastname: Babcock
authors.forename: M A
authors.initials: MA
authors.lastname: Marletta
mesh_terms: D000818:Animals; D004926:Escherichia coli; D006162:Guanylate Cyclase / Q000737:chemistry* / Q000378:metabolism; D007191:Indazoles / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D011485:Protein Binding; D013059:Spectrum Analysis, Raman
chemical_list: D007191:Indazoles; C090937:3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole; D006162:Guanylate Cyclase