Interaction Site for High-Potential Iron-Sulfur Protein on the Tetraheme Cytochrome Subunit Bound to the Photosynthetic Reaction Center of Rubrivivax gelatinosus

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• 作者：Artur Osyczka ; Kenji V. P. Nagashima ; Keizo Shimada ; and Katsumi Matsuura
• 刊名：Biochemistry
• 出版年：1999
• 出版时间：March 9, 1999
• 年：1999
• 卷：38
• 期：10
• 页码：2861 - 2865
• 全文大小：104K
• 年卷期：v.38,no.10(March 9, 1999)
• ISSN：1520-4995

文摘

We have recently demonstrated, using site-directed mutagenesis, that soluble cytochromesinteract with the Rubrivivax gelatinosus photosynthetic reaction center (RC) in the vicinity of the low-potential heme 1 (c-551, E_m = 70 mV) of the tetraheme cytochrome subunit, the fourth heme from thespecial pair of bacteriochlorophyll [Osyczka, A., et al. (1998) Biochemistry 37, 11732-11744]. Althoughthe mutations generated in that study did not show clear effects on the electron transfer from high-potentialiron-sulfur protein (HiPIP), which is the major physiological electron donor to the RC in this bacterium,we report here that other site-directed mutations near the solvent-exposed edge of the same low-potentialheme 1, V67K (valine-67 substituted by lysine) and E79K/E85K/E93K (glutamates-79, -85, and -93, allreplaced by lysines), considerably inhibit the electron transfer from HiPIP to the RC. Thus, it is concludedthat HiPIP, like soluble cytochromes, binds to the RC in the vicinity of the exposed part of the low-potential heme 1 of the cytochrome subunit, although some differences in the configurations of the HiPIP-RC and cytochrome c-RC transient complexes may be postulated.