1huv
CRYSTAL STRUCTURE OF A SOLUBLE MUTANT OF THE MEMBRANE-ASSOCIATED (S)-MANDELATE DEHYDROGENASE FROM PSEUDOMONAS PUTIDA AT 2.15A RESOLUTION
Structural highlights
FunctionMDLB_PSEPU Reduction of (S)-mandelate to benzoylformate.GOX_SPIOL Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe structure of an active mutant of (S)-mandelate dehydrogenase (MDH-GOX2) from Pseudomonas putida has been determined at 2.15 A resolution. The membrane-associated flavoenzyme (S)-mandelate dehydrogenase (MDH) catalyzes the oxidation of (S)-mandelate to give a flavin hydroquinone intermediate which is subsequently reoxidized by an organic oxidant residing in the membrane. The enzyme was rendered soluble by replacing its 39-residue membrane-binding peptide segment with a corresponding 20-residue segment from its soluble homologue, glycolate oxidase (GOX). Because of their amphipathic nature and peculiar solubilization properties, membrane proteins are notoriously difficult to crystallize, yet represent a large fraction of the proteins encoded by genomes currently being deciphered. Here we present the first report of such a structure in which an internal membrane-binding segment has been replaced, leading to successful crystallization of the fully active enzyme in the absence of detergents. This approach may have general application to other membrane-bound proteins. The overall fold of the molecule is that of a TIM barrel, and it forms a tight tetramer within the crystal lattice that has circular 4-fold symmetry. The structure of MDH-GOX2 reveals how this molecule can interact with a membrane, although it is limited by the absence of a membrane-binding segment. MDH-GOX2 and GOX adopt similar conformations, yet they retain features characteristic of membrane and globular proteins, respectively. MDH-GOX2 has a distinctly electropositive surface capable of interacting with the membrane, while the opposite surface is largely electronegative. GOX shows no such pattern. MDH appears to form a new class of monotopic integral membrane protein that interacts with the membrane through coplanar electrostatic binding surfaces and hydrophobic interactions, thus combining features of both the prostaglandin synthase/squaline-hopine cyclase and the C-2 coagulation factor domain classes of membrane proteins. Structure of an active soluble mutant of the membrane-associated (S)-mandelate dehydrogenase.,Sukumar N, Xu Y, Gatti DL, Mitra B, Mathews FS Biochemistry. 2001 Aug 21;40(33):9870-8. PMID:11502180[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences | ||||||||||||||||||||
