Author:
Moldenhauer Marcus,Tseng Hsueh-Wei,Kraskov Anastasia,Tavraz Neslihan N.,Yaroshevich Igor A.,Hildebrandt Peter,Sluchanko Nikolai N.,Hochberg Georg A.,Essen Lars-Oliver,Budisa Nediljko,Korf Lukas,Maksimov Eugene G.,Friedrich Thomas
Abstract
Introduction: Dissecting the intricate networks of covalent and non-covalent interactions that stabilize complex protein structures is notoriously difficult and requires subtle atomic-level exchanges to precisely affect local chemical functionality. The function of the Orange Carotenoid Protein (OCP), a light-driven photoswitch involved in cyanobacterial photoprotection, depends strongly on two H-bonds between the 4-ketolated xanthophyll cofactor and two highly conserved residues in the C-terminal domain (Trp288 and Tyr201).Method: By orthogonal translation, we replaced Trp288 in Synechocystis OCP with 3-benzothienyl-L-alanine (BTA), thereby exchanging the imino nitrogen for a sulphur atom.Results: Although the high-resolution (1.8 Å) crystal structure of the fully photoactive OCP-W288_BTA protein showed perfect isomorphism to the native structure, the spectroscopic and kinetic properties changed distinctly. We accurately parameterized the effects of the absence of a single H-bond on the spectroscopic and thermodynamic properties of OCP photoconversion and reveal general principles underlying the design of photoreceptors by natural evolution.Discussion: Such “molecular surgery” is superior over trial-and-error methods in hypothesis-driven research of complex chemical systems.
Funder
Deutsche Forschungsgemeinschaft
Subject
Biochemistry, Genetics and Molecular Biology (miscellaneous),Molecular Biology,Biochemistry
Cited by
2 articles.
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