1X8N

1.08 A Crystal Structure Of Nitrophorin 4 From Rhodnius Prolixus Complexed With Nitric Oxide at pH 7.4

1X8N の概要

• エントリーDOI: 10.2210/pdb1x8n/pdb
• 関連するPDBエントリー: 1D2U 1KOI 1X8O 1X8P 1X8Q
• 分子名称: Nitrophorin 4, PROTOPORPHYRIN IX CONTAINING FE, NITRIC OXIDE, ... (4 entities in total)
• 機能のキーワード: lipocalin; beta barrel; heme; nitric oxide, ligand binding protein
• 由来する生物種: Rhodnius prolixus
• 細胞内の位置: Secreted: Q94734
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 20939.16

構造登録者

Kondrashov, D.A.,Roberts, S.A.,Weichsel, A.,Montfort, W.R. (登録日: 2004-08-18, 公開日: 2004-10-05, 最終更新日: 2024-11-20)

主引用文献

Kondrashov, D.A.,Roberts, S.A.,Weichsel, A.,Montfort, W.R.
Protein functional cycle viewed at atomic resolution: conformational change and mobility in nitrophorin 4 as a function of pH and NO binding
Biochemistry, 43:13637-13647, 2004

PubMed Abstract: The blood-sucking insect Rhodnius prolixus uses nitrophorin 4, a heme protein, to deliver nitric oxide (NO) to a victim, causing vasodilation and improved feeding. Binding of NO occurs at a ferric heme and is modulated by pH. NO binding at lower pH induces a large conformational change involving loops A-B and G-H that leads to distal pocket desolvation and protection of the nitrosyl heme complex. We have determined the crystal structures of Rhodnius nitrophorin 4 to ultrahigh resolution in four functional states: +/-NO at pH = 7.4 and +/-NO at pH = 5.6. The structure with NO at pH 7.4 (1.08 A) is newly determined while the other complexes have been modeled to resolutions much greater than previously reported (1.0-0.85 A). The ultrahigh resolution allowed us to resolve multiple conformers in binding-site loops, leading to a detailed description of the dynamics involved with storing NO in the insect salivary gland at low pH, and releasing NO in response to the increased pH of a victim's tissue. Strikingly, features for both the "open" and "closed" conformers exist under all conditions, suggesting that the flexible loops can transition with relative ease between conformational states. Yet, release of NO from rNP4 is much slower than found for other ferric heme proteins. The structures suggest that highly mobile loops can limit diffusion of diatomic molecules into and out of a protein cavity, a result with implications for the role of protein dynamics in function.

PubMed: 15504026
DOI: 10.1021/bi0483155

実験手法

X-RAY DIFFRACTION (1.08 Å)