Communication between the zinc and tetrahydrobiopterin binding sites in nitric oxide synthase

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Chreifi, Georges and Li, Huiying and McInnes, Craig and Gibson, Colin and Suckling, Colin and Poulos, Thomas L (2014) Communication between the zinc and tetrahydrobiopterin binding sites in nitric oxide synthase. Biochemistry. ISSN 0006-2960 (https://doi.org/10.1021/bi5003986)

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Abstract

The nitric oxide synthase (NOS) dimer is stabilized by a Zn2+ ion coordinated to four symmetry-related Cys residues exactly along the dimer 2-fold axis. Each of the two essential tetrahydrobiopterin (H4B) molecules in the dimer interacts directly with the heme, and each H4B molecule is ∼15 Å from the Zn2+. We have determined the crystal structures of the bovine endothelial NOS dimer oxygenase domain bound to three different pterin analogues, which reveal an intimate structural communication between the H4B and Zn2+ sites. The binding of one of these compounds, 6-acetyl-2-amino-7,7-dimethyl-7,8-dihydro-4(3H)-pteridinone (1), to the pterin site and Zn2+ binding are mutually exclusive. Compound 1both directly and indirectly disrupts hydrogen bonding between key residues in the Zn2+ binding motif, resulting in destabilization of the dimer and a complete disruption of the Zn2+ site. Addition of excess Zn2+ stabilizes the Zn2+ site at the expense of weakened binding of 1. The unique structural features of 1 that disrupt the dimer interface are extra methyl groups that extend into the dimer interface and force a slight opening of the dimer, thus resulting in disruption of the Zn2+ site. These results illustrate a very delicate balance of forces and structure at the dimer interface that must be maintained to properly form the Zn2+, pterin, and substrate binding sites.

ORCID iDs

Chreifi, Georges, Li, Huiying, McInnes, Craig, Gibson, Colin ORCID logoORCID: https://orcid.org/0000-0003-4948-1266, Suckling, Colin and Poulos, Thomas L;
  • Item type:Article
    ID code:48874
    Dates:
    Date
    Event
    2014
    Published
    12 May 2014
    Published Online
    Notes:Date of Acceptance:12/05/2014 This document is the unedited Author's version of a Submitted Work that was subsequently accepted for publication in Biochemistry, copyright © American Chemical Society after peer review. To access the final edited and published work see http://dx.doi.org/10.1021/bi5003986.
    Subjects:Science > Chemistry > Physical and theoretical chemistry
    Department:Faculty of Science > Pure and Applied Chemistry
    Depositing user: Pure Administrator
    Date deposited:27 Jun 2014 14:08
    Last modified:11 Nov 2024 10:44
    Related URLs:
    URI:https://strathprints.strath.ac.uk/id/eprint/48874
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