Crystal structure of an oxygen-binding heme domain related to soluble guanylate cyclases.
Soluble guanylate cyclases are nitric oxide-responsive signaling proteins in which the nitric oxide sensor is a heme-binding domain of unknown structure that we have termed the heme-NO and oxygen binding (H-NOX) domain. H-NOX domains are also found in bacteria, either as isolated domains, or are fused through a membrane-spanning region to methyl-accepting chemotaxis proteins. We have determined the crystal structure of an oxygen-binding H-NOX domain of one such signaling protein from the obligate anaerobe Thermoanaerobacter tengcongensis at 1.77-angstroms resolution, revealing a protein fold unrelated to known structures. Particularly striking is the structure of the protoporphyrin IX group, which is distorted from planarity to an extent not seen before in protein-bound heme groups. Comparison of the structure of the H-NOX domain in two different crystal forms suggests a mechanism whereby alteration in the degree of distortion of the heme group is coupled to changes on the molecular surface of the H-NOX domain and potentially to changes in intermolecular interactions.
Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
Patricia
P
Pellicena
David S
DS
Karow
Elizabeth M
EM
Boon
Michael A
MA
Marletta
John
J
Kuriyan
D000595:Amino Acid Sequence; D002633:Chemotaxis / Q000502:physiology; D006162:Guanylate Cyclase / Q000737:chemistry* / Q000378:metabolism; D006418:Heme / Q000378:metabolism*; D008969:Molecular Sequence Data; D010100:Oxygen / Q000378:metabolism*; D017434:Protein Structure, Tertiary
D006418:Heme; D006162:Guanylate Cyclase; D010100:Oxygen