1JWJ

Murine Inducible Nitric Oxide Synthase Oxygenase Dimer (Delta 65) with W457F Mutation at Tetrahydrobiopterin Binding Site

Summary for 1JWJ

• Entry DOI: 10.2210/pdb1jwj/pdb
• Related: 1JWK
• Descriptor: Nitric Oxide Synthase, octyl beta-D-glucopyranoside, PROTOPORPHYRIN IX CONTAINING FE, ... (7 entities in total)
• Functional Keywords: nitric oxide l-arginine monooxygenase, heme, dimer, nos, oxidoreductase
• Biological source: Mus musculus (house mouse)
• Total number of polymer chains: 2
• Total formula weight: 103417.02

Authors

Aoyagi, M.,Arvai, A.S.,Ghosh, S.,Stuehr, D.J.,Tainer, J.A.,Getzoff, E.D. (deposition date: 2001-09-04, release date: 2001-10-31, Last modification date: 2023-08-16)

Primary citation

Aoyagi, M.,Arvai, A.S.,Ghosh, S.,Stuehr, D.J.,Tainer, J.A.,Getzoff, E.D.
Structures of tetrahydrobiopterin binding-site mutants of inducible nitric oxide synthase oxygenase dimer and implicated roles of Trp457.
Biochemistry, 40:12826-12832, 2001

PubMed Abstract: To better understand potential roles of conserved Trp457 of the murine inducible nitric oxide synthase oxygenase domain (iNOS(ox); residues 1-498) in maintaining the structural integrity of the (6R)-5,6,7,8-tetrahydrobiopterin (H(4)B) binding site located at the dimer interface and in supporting H(4)B redox activity, we determined crystallographic structures of W457F and W457A mutant iNOS(ox) dimers (residues 66-498). In W457F iNOS(ox), all the important hydrogen-bonding and aromatic stacking interactions that constitute the H(4)B binding site and that bridge the H(4)B and heme sites are preserved. In contrast, the W457A mutation results in rearrangement of the Arg193 side chain, orienting its terminal guanidinium group almost perpendicular to the ring plane of H(4)B. Although Trp457 is not required for dimerization, both Trp457 mutations led to the increased mobility of the N-terminal H(4)B binding segment (Ser112-Met114), which might indicate reduced stability of the Trp457 mutant dimers. The Trp457 mutant structures show decreased pi-stacking with bound pterin when the wild-type pi-stacking Trp457 position is occupied with the smaller Phe457 in W457F or positive Arg193 in W457A. The reduced pterin pi-stacking in these mutant structures, relative to that in the wild-type, implies stabilization of reduced H(4)B and destabilization of the pterin radical, consequently slowing electron transfer to the heme ferrous-dioxy (Fe(II)O(2)) species during catalysis. These crystal structures therefore aid elucidation of the roles and importance of conserved Trp457 in maintaining the structural integrity of the H(4)B binding site and of H(4)B-bound dimers, and in influencing the rate of electron transfer between H(4)B and heme in NOS catalysis.

PubMed: 11669619
DOI: 10.1021/bi011183k

Experimental method

X-RAY DIFFRACTION (2.6 Å)