Nitric oxide binding to nitrophorin 4 induces complete distal pocket burial

Andrzej Weichsel, John F. Andersen, Sue A. Roberts, William R. Montfort

Research output: Contribution to journalArticlepeer-review

118 Scopus citations


The nitrophorins comprise an unusual family of proteins that use ferric (Fe(III)) heme to transport highly reactive nitric oxide (NO) from the salivary gland of a blood sucking bug to the victim, resulting in vasodilation and reduced blood coagulation. We have determined structures of nitrophorin 4 in complexes with H2O, cyanide and nitric oxide. These structures reveal a remarkable feature: the nitrophorins have a broadly open distal pocket in the absence of NO, but upon NO binding, three or more water molecules are expelled and two loops fold into the distal pocket, resulting in the packing of hydrophobic groups around the NO molecule and increased distortion of the heme. In this way, the protein apparently forms a 'hydrophobic trap' for the NO molecule. The structures are very accurate, ranging between 1.6 and 1.4 A resolutions.

Original languageEnglish (US)
Pages (from-to)551-554
Number of pages4
JournalNature Structural Biology
Issue number7
StatePublished - Jul 2000

ASJC Scopus subject areas

  • Structural Biology
  • Biochemistry
  • Genetics


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