title: Human Drg1 is a potassium-dependent GTPase enhanced by Lerepo4.
abstract: Human Drg1, a guanine nucleotide binding protein conserved in archaea and eukaryotes, is regulated by Lerepo4. Together they form a complex which interacts with translating ribosomes. Here we have purified and characterized the GTPase activity of Drg1 and three variants, a shortened mutant depleted of the TGS domain, a phosphomimicking mutant and a construct with the two combined mutations. Our data reveal that potassium strongly stimulates the GTPase activity, without changing the monomeric status of Drg1 and that this activity is notably reduced in the mutants. The nature of Lerepo4 association has also been investigated. Dissecting the role of the different domains revealed that Dfrp domain is the sole responsible for the Drg1 increase in thermal stability and the four fold stimulation over its catalytic activity. Lerepo4 action leaves Drg1 affinity for nucleotides unaffected, feasibly favoring a switch I reorientation, mainly via the TGS domain. Drg1 displayed a high temperature optimum of activity at 42°C, suggesting the ability of being active under possible heat stress conditions.
authors.affiliation: Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Científicas, Valencia, Spain.
authors.forename: Isabel
authors.initials: I
authors.lastname: Pérez-Arellano
authors.forename: Mercedes
authors.initials: M
authors.lastname: Spínola-Amilibia
authors.forename: Jerónimo
authors.initials: J
authors.lastname: Bravo
mesh_terms: D002352:Carrier Proteins / Q000737:chemistry*; D004795:Enzyme Stability; D019204:GTP-Binding Proteins / Q000737:chemistry*; D006153:Guanosine Diphosphate / Q000737:chemistry; D006160:Guanosine Triphosphate / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010766:Phosphorylation; D011188:Potassium / Q000737:chemistry*; D055503:Protein Multimerization; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D016601:RNA-Binding Proteins
chemical_list: D002352:Carrier Proteins; D016601:RNA-Binding Proteins; C583533:ZC3H15 protein, human; D006153:Guanosine Diphosphate; C078418:developmentally regulated GTP-binding protein; D006160:Guanosine Triphosphate; D019204:GTP-Binding Proteins; D011188:Potassium
keywords: Drg1; Lerepo4; TGS domain; potassium-dependent stimulation; ribosome binding GTPase