1NTF

Crystal Structure of Cimex Nitrophorin

1NTF の概要

• エントリーDOI: 10.2210/pdb1ntf/pdb
• 分子名称: salivary nitrophorin, PROTOPORPHYRIN IX CONTAINING FE (3 entities in total)
• 機能のキーワード: ferric heme protein, beta sandwich, no carrier, transport protein
• 由来する生物種: Cimex lectularius (bed bug)
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 32362.96

構造登録者

Weichsel, A.,Maes, E.M.,Andersen, J.F.,Valenzuela, J.G.,Walker, F.A.,Montfort, W.R. (登録日: 2003-01-29, 公開日: 2004-03-16, 最終更新日: 2024-02-14)

主引用文献

Weichsel, A.,Maes, E.M.,Andersen, J.F.,Valenzuela, J.G.,Shokhireva, T.K.,Walker, F.A.,Montfort, W.R.
Heme-assisted S-nitrosation of a proximal thiolate in a nitric oxide transport protein.
Proc.Natl.Acad.Sci.USA, 102:594-599, 2005

PubMed Abstract: Certain bloodsucking insects deliver nitric oxide (NO) while feeding, to induce vasodilation and inhibit blood coagulation. We have expressed, characterized, and determined the crystal structure of the Cimex lectularius (bedbug) nitrophorin, the protein responsible for NO storage and delivery, to understand how the insect successfully handles this reactive molecule. Surprisingly, NO binds not only to the ferric nitrophorin heme, but it can also be stored as an S-nitroso (SNO) conjugate of the proximal heme cysteine (Cys-60) when present at higher concentrations. EPR- and UV-visible spectroscopies, and a crystallographic structure determination to 1.75-A resolution, reveal SNO formation to proceed with reduction of the heme iron, yielding an Fe-NO complex. Stopped-flow kinetic measurements indicate that an ordered reaction mechanism takes place: initial NO binding occurs at the ferric heme and is followed by heme reduction, Cys-60 release from the heme iron, and SNO formation. Release of NO occurs through a reversal of these steps. These data provide, to our knowledge, the first view of reversible metal-assisted SNO formation in a protein and suggest a mechanism for its role in NO release from ferrous heme. This mechanism and Cimex nitrophorin structure are completely unlike those of the nitrophorins from Rhodnius prolixus, where NO protection is provided by a large conformational change that buries the heme nitrosyl complex, highlighting the remarkable evolution of proteins that assist insects in bloodfeeding.

PubMed: 15637157
DOI: 10.1073/pnas.0406549102

実験手法

X-RAY DIFFRACTION (1.8 Å)