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

Kaur, Ramandeep and Ahuja, Sandhya and Anand, Arvind and Singh, Balvinder and Stark, Benjamin C and Webster, Dale A and Dikshit, Kanak L (2008) Functional implications of the proximal site hydrogen bonding network in Vitreoscilla hemoglobin (VHb): role of Tyr95 (G5) and Tyr126 (H12). FEBS letters, 582 (23-24). pp. 3494-500. ISSN 0014-5793

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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.

Item Type:	Article
Additional Information:	Copyright of this article belongs to Elsevier Science
Uncontrolled Keywords:	Bacterial hemoglobin; Ligand binding; Vitreoscilla hemoglobin; Flavohemoglobin; Proximal heme site; Distal heme site; Molecular modeling
Subjects:	Q Science > QR Microbiology
Depositing User:	Dr. K.P.S.Sengar
Date Deposited:	08 Dec 2011 19:37
Last Modified:	07 Jan 2015 08:34
URI:	http://crdd.osdd.net/open/id/eprint/581

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