title: Mapping of heme-binding domains in soluble guanylyl cyclase beta1 subunit.
abstract: Soluble guanylyl cyclase (sGC) is activated upon the interaction of NO with heme in the sGC beta1 subunit. To identify the domains contributing to heme-binding, we constructed a series of deletion mutants of the beta1 subunit, and evaluated their heme-binding capability. Deletion mutants consisting of residues 1-120 [beta1(1-120)] and 80-385 [beta1(80-385)] were the shortest mutants exhibiting heme binding among the C-terminal and N-terminal-truncated mutants, respectively. The region common to both beta1(1-120) and beta1(80-385), i.e., residues 80-120, is therefore essential for heme binding, although the residues 341-385 play an auxiliary role in heme binding. Two deletion mutants, beta1(80-195) and beta1(60-195), which include only the essential region, exhibited strong heme binding and spectral properties similar to those of the nitrosyl complex of native sGC. Thus, these heme-binding core proteins may serve as model proteins for future studies on the tertiary structure of the nitrosyl complex of sGC.
authors.affiliation: Department of Pharmacology, Graduate School of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Namiki
authors.forename: K
authors.initials: K
authors.lastname: Hirose
authors.forename: M
authors.initials: M
authors.lastname: Iino
mesh_terms: D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000201:enzymology / Q000378:metabolism; D004227:Dithionite / Q000378:metabolism; D006162:Guanylate Cyclase; D006418:Heme / Q000378:metabolism*; D007093:Imidazoles / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D021122:Protein Subunits; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion / Q000235:genetics; D000071756:Soluble Guanylyl Cyclase; D013057:Spectrum Analysis; D013879:Thioredoxins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D007093:Imidazoles; D021122:Protein Subunits; D018160:Receptors, Cytoplasmic and Nuclear; D011993:Recombinant Fusion Proteins; D004227:Dithionite; D009569:Nitric Oxide; D006418:Heme; D013879:Thioredoxins; C029899:imidazole; D006162:Guanylate Cyclase; D000071756:Soluble Guanylyl Cyclase