High-Resolution Structure of the Soluble, Respiratory-Type Rieske Protein from Thermus thermophilus: Analysis and Comparison

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• 作者：Laura M. Hunsicker-Wang ; Andreas Heine ; Ying Chen ; Eugene P. Luna ; Thomas Todaro ; Yan Ming Zhang ; Pamela A. Williams ; Duncan E. McRee ; ^O ; Judy Hirst ; C. David Stout ; and James A. Fee
• 刊名：Biochemistry
• 出版年：2003
• 出版时间：June 24, 2003
• 年：2003
• 卷：42
• 期：24
• 页码：7303 - 7317
• 全文大小：1149K
• 年卷期：v.42,no.24(June 24, 2003)
• ISSN：1520-4995

文摘

The structure of the soluble Rieske protein from Thermus thermophilus has been determinedat a resolution of 1.3 Å at pH 8.5 using multiwavelength anomalous dispersion (MAD) techniques. Thisis the first report of a Rieske protein from a menaquinone-utilizing organism. The structure shows anoverall fold similar to previously reported Rieske proteins. A novel feature of this crystal form appearsto be a shared hydrogen between the His-134 imidazole ring ligated to Fe2 of the [2Fe-2S] cluster andits symmetry partner, His-134', one being formally an imidazolate anion, Fe2-(His-134)N^-···H-N'(His-134')-Fe2', in which crystallographic C₂ axes pass equidistant between N···N' and normal to theline defined by N···N'. This provides evidence for a stable, oxidized cluster with a His^- ligand andlends support to a previously proposed mechanism of coupled proton and electron transfer. A detailedcomparison of the Thermus Rieske protein with six other Rieske and Rieske-type proteins indicates: (a)The cluster binding domain is tightly conserved. (b) The 3-D structure of the 10 -strand fold is conserved,even among the most divergent proteins. (c) There is an approximately linear relation between acid-pHredox potential and number of H-bonds to the cluster. (d) These proteins have two faces, one points intothe larger complex (bc₁, b₆f, or other), is involved in the proton coupled electron transfer function, and ishighly conserved. The second is oriented toward the solvent and shows wide variation in charge, sequence,length, hydrophobicity, and secondary elements in the loops that connect the -sheets.