Gene sequence and the 1.8 Å crystal structure of the tungsten-containing formate dehydrogenase from Desulfovibrio gigas
This work was supported by EC-TMR/FMRX-CT980204, PhD grant PRAXISXXI/BD/16009/98 (S.M.), and PhD grant PRAXISXXI/BD/13530/97 (J.M.D.). We thank the EMBL Grenoble Outstation, beamline BM-14, for MAD measurements at the ESRF under the European Union TMR/LSF Program. Hans Bartunik and Gleb Bourenkov are acknowledged for help at the BW6 beamline of the MPG-ASMB in DESY, Hamburg, for collecting the first FDH native data set. The Institute for Genomic Research (TIGR) is kindly acknowledged for making the preliminary sequence data on the Desulfovibrio vulgaris Hildenborough genome available to the public at their Website ( http://www.tigr.org ). ; Desulfovibrio gigas formate dehydrogenase is the first representative of a tungsten-containing enzyme from a mesophile that has been structurally characterized. It is a heterodimer of 110 and 24 kDa subunits. The large subunit, homologous to E. coli FDH-H and to D. desulfuricans nitrate reductase, harbors the W site and one [4Fe-4S] center. No small subunit ortholog containing three [4Fe-4S] clusters has been reported. The structural homology with E. coli FDH-H shows that the essential residues (SeCys158, His159, and Arg407) at the active site are conserved. The active site is accessible via a positively charged tunnel, while product release may be facilitated, for H+ by buried waters and protonable amino acids and for CO2 through a hydrophobic channel. ; publishersversion ; published