1EQD

CRYSTAL STRUCTURE OF NITROPHORIN 4 COMPLEXED WITH CN

Summary for 1EQD

• Entry DOI: 10.2210/pdb1eqd/pdb
• Related: 1D3S 1ERX
• Descriptor: NITROPHORIN 4, CYANIDE ION, 5,8-DIMETHYL-1,2,3,4-TETRAVINYLPORPHINE-6,7-DIPROPIONIC ACID FERROUS COMPLEX, ... (5 entities in total)
• Functional Keywords: beta barrel, lipocalin fold, ferric heme, cyanide, signaling protein
• Biological source: Rhodnius prolixus
• Cellular location: Secreted: Q94734
• Total number of polymer chains: 1
• Total formula weight: 21151.31

Authors

Weichsel, A.,Andersen, J.F.,Roberts, S.A.,Montfort, W.R. (deposition date: 2000-04-03, release date: 2000-05-03, Last modification date: 2024-11-20)

Primary citation

Weichsel, A.,Andersen, J.F.,Roberts, S.A.,Montfort, W.R.
Nitric oxide binding to nitrophorin 4 induces complete distal pocket burial.
Nat.Struct.Biol., 7:551-554, 2000

PubMed Abstract: 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.

PubMed: 10876239
DOI: 10.1038/76769

Experimental method

X-RAY DIFFRACTION (1.6 Å)