Histidine 114 is critical for ATP hydrolysis by the universally conserved ATPase YchF [Protein Synthesis and Degradation]

May 27th, 2015 by Rosler, K. S., Mercier, E., Andrews, I. C., Wieden, H.-J.

GTPases perform a wide range of functions, ranging from protein synthesis to cellular signaling. Of all known GTPases, only eight are conserved across all three domains of life. YchF is one of these eight universally conserved GTPases, however its cellular function and enzymatic properties are poorly understood. YchF differs from the classical GTPases in that it has a higher affinity for ATP than for GTP and is a functional ATPase. As a HAS-ATPase, YchF does not possess the canonical Glncat required for nucleotide hydrolysis. In order to elucidate the catalytic mechanism of ATP hydrolysis by YchF, we have taken a two-pronged approach combining classical biochemical and in silico techniques. The use of molecular dynamics (MD) simulations allowed us to complement our biochemical findings with information about the structural dynamics of YchF. Thereby we have identified the highly conserved Histidine residue 114 as critical for the intrinsic ATPase activity in YchF from Escherichia coli. His 114 is located in a flexible loop of the G-domain, which undergoes nucleotide-dependent conformational changes. The use of a catalytic Histisine is also observed in the HAS-GTPase RbgA and is an identifier of the trGTPase family.