Atypical Switch-I Arginine plays a catalytic role in GTP hydrolysis by Rab21 from Entamoeba histolytica.

Atypical Switch-I Arginine plays a catalytic role in GTP hydrolysis by Rab21 from Entamoeba histolytica. Biochem Biophys Res Commun. 2018 Nov 30;506(3):660-667 Authors: Kotyada C, Chandra M, Tripathi A, Narooka AR, Datta S, Verma A Abstract Entamoeba histolytica, the causative agent of amoebic dysentery, liver abscess and colitis, exploits its vesicular trafficking machinery for survival and virulence. Rab family of small GTPases play a key role in the vesicular transport by undergoing the GTP/GDP cycle which is central to the biological processes. Amoebic genome encodes several atypical Rab GTPases which are unique due to absence of conserved sequence motif(s) or atypical residues in their catalytic site [Saito-Nakano et al., 2005 ]. Previously, EhRab21 has been reported to involve in amoebic invasion and migration [Emmanuel et al., 2015 ]. The conserved Glutamine of switch-II region is universally accepted to be crucial for GTP hydrolysis. Mutations that reduce the sidechain polarity of Glutamine render the protein GTPase activity deficient [Krengel et al., 1990]. Here, we report a catalytic role of atypical switch-I Arginine (R36) in intrinsic GTP hydrolysis catalysed by EhRab21. Unlike the GTPase activity deficient QL mutants, the GTPase activity of EhRab21Q64L was found to be marginally enhanced compared to the wild-type protein. Although EhRab21R36L mutant showed normal GTPase activity, the double mutant (R36L/Q64L) was foun...
Source: Biochemical and Biophysical Research communications - Category: Biochemistry Authors: Tags: Biochem Biophys Res Commun Source Type: research