title: Diversity and plasticity in Rab GTPase nucleotide release mechanism has consequences for Rab activation and inactivation.
abstract: Ras superfamily GTPase activation and inactivation occur by canonical nucleotide exchange and GTP hydrolysis mechanisms. Despite conservation of active-site residues, the Ras-related Rab GTPase activation pathway differs from Ras and between different Rabs. Analysis of DENND1-Rab35, Rabex-Rab5, TRAPP-Rab1 and DrrA-Rab1 suggests Rabs have the potential for activation by distinct GDP-release pathways. Conserved active-site residues in the Rab switch II region stabilising the nucleotide-free form differentiate these pathways. For DENND1-Rab35 and DrrA-Rab1 the Rab active-site glutamine, often mutated to create constitutively active forms, is involved in GEF mediated GDP-release. By contrast, in Rab5 the switch II aspartate is required for Rabex mediated GDP-release. Furthermore, Rab1 switch II glutamine mutants refractory to activation by DrrA can be activated by TRAPP, showing that a single Rab can be activated by more than one mechanistically distinct GDP-release pathway. These findings highlight plasticity in the activation mechanisms of closely related Rab GTPases. DOI: http://dx.doi.org/10.7554/eLife.01623.001.
authors: Department of Biochemistry, University of Oxford, Oxford, United Kingdom.
authors: Lars
authors: L
authors: Langemeyer
authors: Ricardo
authors: R
authors: Nunes Bastos
authors: Yiying
authors: Y
authors: Cai
authors: Aymelt
authors: A
authors: Itzen
authors: Karin M
authors: KM
authors: Reinisch
authors: Francis A
authors: FA
authors: Barr
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001224:Aspartic Acid; D001426:Bacterial Proteins / Q000378:metabolism; D020134:Catalytic Domain; D004268:DNA-Binding Proteins / Q000378:metabolism; D053418:Death Domain Receptor Signaling Adaptor Proteins / Q000378:metabolism; D004789:Enzyme Activation; D005973:Glutamine; D020662:Guanine Nucleotide Exchange Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D006868:Hydrolysis; D008087:Listeria / Q000378:metabolism; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D011487:Protein Conformation; D015398:Signal Transduction; D014162:Transfection; D020691:rab GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020761:rab1 GTP-Binding Proteins / Q000378:metabolism; D020696:rab5 GTP-Binding Proteins / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; C546321:DENND1B protein, human; D004268:DNA-Binding Proteins; D053418:Death Domain Receptor Signaling Adaptor Proteins; C101895:DrrA protein, Bacteria; D020662:Guanine Nucleotide Exchange Factors; C108382:RABGEF1 protein, human; D005973:Glutamine; D001224:Aspartic Acid; D000255:Adenosine Triphosphate; C511183:RAB35 protein, human; C427755:RAB5C protein, human; D020691:rab GTP-Binding Proteins; D020761:rab1 GTP-Binding Proteins; D020696:rab5 GTP-Binding Proteins
keywords: Rab GTPase; membrane traffic; nucleotide exchange factor