Otomo J
PRESTO, JRDC and Advanced Research Laboratory, Hitachi, Ltd., Saitama, Japan.
Biophys Chem. 1995 Sep-Oct;56(1-2):137-41. doi: 10.1016/0301-4622(95)00025-s.
Comparison of the amino acid sequences in the A-B and B-C interhelical loop segments in all bacteriorhodopsins and halorhodopsins has shed light on the anion selectivity and pumping mechanism of halorhodopsin. The nucleotide sequences of two haloopsins from two new halobacterial strains, shark and port, have been determined, and shark halorhodopsin was functionally overexpressed in Halobacterium halobium. Although a series of six amino acid residues (EMPAGH) in the B-C interhelical loop segment was substituted by QMPPGH, all putative charged residues were conserved. It was also shown that His-95 mutants had lower pumping activity in low chloride concentrations. These results further support the hypothesis that His-95 is important in the halorhodopsin function.
对所有细菌视紫红质和嗜盐菌视紫红质中A - B和B - C螺旋间环段氨基酸序列的比较，揭示了嗜盐菌视紫红质的阴离子选择性和泵浦机制。已测定了来自两种新的嗜盐细菌菌株（鲨鱼菌和港口菌）的两种嗜盐菌视紫红质的核苷酸序列，并且鲨鱼嗜盐菌视紫红质在嗜盐栖热菌中实现了功能性过表达。尽管B - C螺旋间环段中的一系列六个氨基酸残基（EMPAGH）被QMPPGH取代，但所有推定的带电残基均得以保留。研究还表明，组氨酸95突变体在低氯浓度下具有较低的泵浦活性。这些结果进一步支持了组氨酸95在嗜盐菌视紫红质功能中起重要作用这一假说。
