2fzm
Structure of the E. coli PutA proline dehydrogenase domain reduced by dithionite and complexed with SO2
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OverviewOverview
PutA is a novel flavoprotein in Escherichia coli that switches from a, transcriptional repressor to a membrane-bound proline catabolic enzyme., Previous crystallographic studies of the PutA proline dehydrogenase, (PRODH) domain under oxidizing conditions revealed that FAD N(5) and the, ribityl 2'-OH group form hydrogen bonds with Arg431 and Arg556, respectively. Here we identify molecular interactions in the PutA PRODH, active site that underlie redox-dependent functional switching of PutA. We, report that reduction of the PRODH domain induces major structural changes, in the FAD cofactor, including a 22 degrees bend of the isoalloxazine ring, along the N(5)-N(10) axis, crankshaft rotation of the upper part of the, ribityl chain, and formation of a new hydrogen bond network involving the, ribityl 2'-OH group, FAD N(1), and Gly435. The roles of the FAD 2'-OH, group and the FAD N(5)-Arg431 hydrogen bond pair in regulating, redox-dependent PutA-membrane associations were tested using FAD analogues, and site-directed mutagenesis. Kinetic membrane binding measurements and, cell-based reporter gene assays of modified PutA proteins show that, disrupting the FAD N(5)-Arg431 interaction impairs the reductive, activation of PutA-membrane binding. We also show that the FAD 2'-OH group, acts as a redox-sensitive toggle switch that controls PutA-membrane, binding. These results illustrate a new versatility of the ribityl chain, in flavoprotein mechanisms.
About this StructureAbout this Structure
2FZM is a Single protein structure of sequence from Escherichia coli with FAD and SO2 as ligands. Active as Proline dehydrogenase, with EC number 1.5.99.8 Full crystallographic information is available from OCA.
ReferenceReference
Redox-induced changes in flavin structure and roles of flavin N(5) and the ribityl 2'-OH group in regulating PutA--membrane binding., Zhang W, Zhang M, Zhu W, Zhou Y, Wanduragala S, Rewinkel D, Tanner JJ, Becker DF, Biochemistry. 2007 Jan 16;46(2):483-91. PMID:17209558
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