Sequence and structural comparison of GEFs from different origins.
(A) Sequence alignment of SopE-type (upper alignment) and WxxxE-type (lower alignment) bacterial effector proteins with postulated Rho GTPase activity; >80% identity is shaded in red, >50% in grey. The residues shown to be important for catalytic GEF activity of SopE  or Map  are marked with asterisks. WxxxE motif and catalytic loops highlighted in (B) are marked with brackets. Note that SifA has a completely different amino acid sequence in its catalytic loop compared to the other proteins in the WxxxE family . (B) Crystal structures of GEFs from different organisms in complex with Cdc42 (orange). Left panel: SopE (cyan) from S. Typhimurium ; the catalytic loop is highlighted in red. Middle panel: Map (pink) from enteropathogenic E. coli ; the WxxxE motif is highlighted in blue and the catalytic loop in red. Right panel: Human Tiam1 (pale blue); only the Rho GTPase binding DH domain is shown . Structures were created using Jmol (http://www.jmol.org/).