3FLL

Crystal structure of E55Q mutant of nitrophorin 4

3FLL の概要

• エントリーDOI: 10.2210/pdb3fll/pdb
• 関連するPDBエントリー: 1D2U
• 分子名称: Nitrophorin-4, PROTOPORPHYRIN IX CONTAINING FE, AMMONIA, ... (4 entities in total)
• 機能のキーワード: beta barrel, lipocalin, heme, mutant, ammonia, iron, metal-binding, secreted, vasoactive, vasodilator, transport protein
• 由来する生物種: Rhodnius prolixus (Triatomid bug)
• 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: 20925.20

構造登録者

Montfort, W.R.,Weichsel, A. (登録日: 2008-12-18, 公開日: 2009-02-10, 最終更新日: 2024-10-09)

主引用文献

Berry, R.E.,Shokhirev, M.N.,Ho, A.Y.,Yang, F.,Shokhireva, T.K.,Zhang, H.,Weichsel, A.,Montfort, W.R.,Walker, F.A.
Effect of mutation of carboxyl side-chain amino acids near the heme on the midpoint potentials and ligand binding constants of nitrophorin 2 and its NO, histamine, and imidazole complexes.
J.Am.Chem.Soc., 131:2313-2327, 2009

PubMed Abstract: Nitrophorins (NPs) are a group of NO-carrying heme proteins found in the saliva of a blood-sucking insect from tropical Central and South America, Rhodnius prolixus, the "kissing bug". NO is kept stable for long periods of time by binding it as an axial ligand to a ferriheme center. The fact that the nitrophorins are stabilized as Fe(III)-NO proteins is a unique property because most heme proteins are readily autoreduced by excess NO and bind NO to the Fe(II) heme irreversibly (K(d)s in the picomolar range). In contrast, the nitrophorins, as Fe(III) heme centers, have K(d)s in the micromolar to nanomolar range and thus allow NO to dissociate upon dilution following injection into the tissues of the victim. This NO can cause vasodilation and thereby allow more blood to be transported to the site of the wound. We prepared 13 site-directed mutants of three major nitrophorins, NP2, NP1, and NP4, to investigate the stabilization of the ferric-NO heme center and preservation of reversible binding that facilitates these proteins' NO storage, transport, and release functions. Of the mutations in which Glu and/or Asp were replaced by Ala, most of these carboxyls show a significant role stabilizing Fe(III)-NO over Fe(II)-NO, with buried E53 of NP2 or E55 of NP1 and NP4 being the most important and partially buried D29 of NP2 or D30 of NP4 being second in importance. The pK(a)s of the carboxyl groups studied vary significantly but all are largely deprotonated at pH 7.5 except E124.

PubMed: 19175316
DOI: 10.1021/ja808105d

実験手法

X-RAY DIFFRACTION (1.5 Å)