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Structural and biochemical analysis of the interaction of Ras with GTPase activating proteins (GAPs) explains the stereochemical basis for the GAP mediated GTPase stimulation.
Members of the family of fungal Zn2Cys6 DNA-binding proteins discriminate between their DNA targets using neither their DNA-binding module, nor their dimerization domain, but primarily through the relatively flexible linker between them.
RasGAPs supply a catalytic residue, termed the arginine finger, into the active site of Ras thereby stabilizing the transition state of the GTPase reaction and increasing the reaction rate by more than one thousand-fold, in good agreement with the structure of the RasṁRasGAP complex.
Combined kinetic and cryo-EM analysis of the R197A mutant of GroEL provides insight into the allosteric switching of GroEL, which is at the heart of the chaperonin mechanism.
The solution structure of the Ras-binding domain (RBD) of Ral guanine-nucleotide exchange factor RalGEF was solved by NMR spectroscopy. The overall structure is similar to that of Raf-RBD, another effector of Ras, although the sequence identity is only 13%. 1SN chemical shifts changes in the complex of RalGEF-RBD with Ras indicate an interaction similar to the intermolecular β-sheet observed for the complex between Ras and Raf-RBD.
RhoA, a ubiquitous intracellular GTPase, mediates cytoskeletal responses to extracellular signals. A 2.1 Å resolution crystal structure of the human RhoA–GDP complex shows unique stereochemistry in the switch I region, which results in a novel mode of Mg2+ binding.
The structure of the N-terminal actin binding domain of human f imbrin offers the first view of an F-actin crosslinking protein and is representative of the conserved actin binding domain found in the largest family of crosslinking proteins. This domain is composed of two calponin homology domains and allows for the mapping of residues implicated in F-actin binding.
The structure and dynamics of the first KH domain of FMR1 — the protein responsible for fragile X syndrome — reveal that an exposed loop is highly flexible despite containing a GxxG motif that is well conserved throughout the KH family. We suggest that this region provides a putative binding surface for RNA recognition.
