Thursday, May 10, 2007

Wolinella succinogenes QFR has a cis-Asp!

(larger image) Wolinella succinogenes QFR flavoprotein has a cis-Asp! Model w atom labels is 2BS2, maps calculated with phases from it using SF's sf2bs2.cif. Other model is chicken complex II, superimposing the FAD domain. Green and red maps are positively and negatively contoured Fo-Fc maps- green on the chickenmodel shows where the atom should be, red on the Wolli atom shows it is misplaced. Apparently this cis-peptide occurs in all membrane-bound SDH/QFR enzymes solved to date. Soluble FCc FRD from Shewanella has a deletion here and no cis-peptide. The cis-peptide introduces a bulge which accomodates the extra residue. This is near the active site and an enigmatic conserved protein-bound metal ion (yellow crosses at bottom center).