Ligand selectivity of soluble guanylyl cyclase: effect of the hydrogen-bonding tyrosine in the distal heme pocket on binding of oxygen, nitric oxide, and carbon monoxide.

Full Abstract

Although soluble guanylyl cyclase (sGC) functions in an environment in which O(2), NO, and CO are potential ligands for its heme moiety, the enzyme displays a high affinity for only its physiological ligand, NO, but has a limited affinity for CO and no affinity for O(2). Recent studies of a truncated version of the sGC beta(1)-subunit containing the heme-binding domain (Boon, E. M., Huang, S H., and Marletta, M. A. (2005) Nat. Chem. Biol., 1, 53-59) showed that introduction of the hydrogen-bonding tyrosine into the distal heme pocket changes the ligand specificity of the heme moiety and results in an oxygen-binding sGC. The hypothesis that the absence of hydrogen-bonding residues in the distal heme pocket is sufficient to provide oxygen discrimination by sGC was put forward. We tested this hypothesis in a context of a complete sGC heterodimer containing both the intact alpha(1)- and beta(1)-subunits. We found that the I145Y substitution in the full-length beta-subunit of the sGC heterodimer did not produce an oxygen-binding enzyme. However, this substitution impeded the association of NO and destabilized the NO.heme complex. The tyrosine in the distal heme pocket also impeded both the binding and dissociation of the CO ligand. We propose that the mechanism of oxygen exclusion by sGC not only involves the lack of hydrogen bonding in the distal heme pocket, but also depends on structural elements from other domains of sGC.

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Author information

Author/s: Martin, Emil (E); Berka, Vladimir (V); Bogatenkova, Elena (E); Murad, Ferid (F); Tsai, Ah-Lim (AL);

Affiliation: Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center, USA. emil.martin(-atsign-)uth.tmc.edu

Grants: DK065153-17 (Agency:NIDDK NIH HHS) ; GM56818 (Agency:NIGMS NIH HHS) ; GM61731 (Agency:NIGMS NIH HHS) ; HL64221 (Agency:NHLBI NIH HHS)

Journal and publication information

Publication Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't

Journal: The Journal of biological chemistry (J Biol Chem), published in United States. (Language: eng)

Reference: 2006-Sep; vol 281 (issue 38) : pp 27836-45

Dates: Created 2006/09/18; Completed 2006/11/02; Revised 2007/11/14;

PMID: 16864588, status: MEDLINE (last retrieval date: 12/26/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Carbon Monoxide - metabolism
Catalysis
Electron Spin Resonance Spectroscopy
Guanylate Cyclase - chemistry; metabolism
Hydrogen Bonding

Hydrogen Bonding
Ligands
Nitric Oxide - metabolism
Oxygen - metabolism
Tyrosine

Associated Chemicals: Ligands (0) ; Nitric Oxide (10102-43-9) ; Tyrosine (55520-40-6) ; Carbon Monoxide (630-08-0) ; Oxygen (7782-44-7) ; Guanylate Cyclase (EC 4.6.1.2)

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