透明颤菌血红蛋白（VHb）近端位点氢键网络的功能意义：酪氨酸95（G5）和酪氨酸126（H12）的作用。

Functional implications of the proximal site hydrogen bonding network in Vitreoscilla hemoglobin (VHb): role of Tyr95 (G5) and Tyr126 (H12).

作者信息

Kaur Ramandeep, Ahuja Sandhya, Anand Arvind, Singh Balwinder, Stark Benjamin C, Webster Dale A, Dikshit Kanak L

机构信息

Institute of Microbial Technology, Sector 39 A, Chandigarh 160036, India.

出版信息

FEBS Lett. 2008 Oct 15;582(23-24):3494-500. doi: 10.1016/j.febslet.2008.09.018. Epub 2008 Sep 18.

DOI:10.1016/j.febslet.2008.09.018

PMID:18804465

Abstract

Although Vitreoscilla hemoglobin (VHb) carries a conventional globin fold, its proximal site geometry is unique in having a hydrogen-bonding network between proximal site residues, HisF8-TyrG5-GluH23 and TyrG5-TyrH12. TyrG5 and TyrH12 were mutated to study their relevance in VHb function. VHb G5 mutants (Tyr95Phe and Tyr95Leu showed no stable oxyform and nitric oxide dioxygenase activity, whereas, VHb H12 mutants (Tyr126Phe and Tyr126Leu) displayed little change in their oxygen affinity indicating a crucial role of Tyr95 in protein function. The VHb H12 mutant, Tyr126Leu, enhanced the intracellular pool of oxygen and cell growth better than VHb. Molecular modeling suggests that the replacement of tyrosine with leucine in Tyr126Leu creates an opening on the protein surface that may facilitate oxygen diffusion and accumulation.

摘要

尽管透明颤菌血红蛋白（VHb）具有传统的球蛋白折叠结构，但其近端位点的几何结构独特，在近端位点残基HisF8-TyrG5-GluH23和TyrG5-TyrH12之间存在氢键网络。对TyrG5和TyrH12进行了突变，以研究它们在VHb功能中的相关性。VHb G5突变体（Tyr95Phe和Tyr95Leu）没有稳定的氧合形式和一氧化氮双加氧酶活性，而VHb H12突变体（Tyr126Phe和Tyr126Leu）的氧亲和力几乎没有变化，这表明Tyr95在蛋白质功能中起关键作用。VHb H12突变体Tyr126Leu比VHb更好地增强了细胞内的氧储备和细胞生长。分子建模表明，Tyr126Leu中酪氨酸被亮氨酸取代在蛋白质表面形成了一个开口，这可能有助于氧的扩散和积累。