3jz9
From Proteopedia
Crystal structure of the GEF domain of DrrA/SidM from Legionella pneumophila
Structural highlights
Function[Q5ZSQ3_LEGPH] Virulence effector that plays a key role in hijacking the host vesicular trafficking by recruiting the small guanosine triphosphatase (GTPase) Rab1 to the cytosolic face of the Legionella-containing vacuole (LCVs). Acts as a GDP-GTP exchange factor (GEF) for the small GTPase Rab1 (RAB1A, RAB1B or RAB1C), thereby converting Rab1 to an active GTP-bound state, leading to the incorporation of Rab1 into LCVs. Also shows RabGDI displacement factor (GDF) activity; however, this probably represents a passive activity following the GEF activity. Also acts as an adenylyltransferase by mediating the addition of adenosine 5'-monophosphate (AMP) to 'Tyr-77' of host RAB1B, thereby rendering RAB1B constitutively active. Also has adenylyltransferase activity towards Rab6 and Rab35. Also displays guanylyltransferase activity by mediating the addition of guanosine 5'-monophosphate (GMP) to host RAB1B in vitro; however such activity remains uncertain in vivo. Specifically binds phosphatidylinositol 4-phosphate (PtdIns(4)P) lipids on the cytosolic surface of the phagosomal membrane shortly after infection.[1] [2] [3] [4] [5] [6] Publication Abstract from PubMedPrenylated Rab proteins exist in the cytosol as soluble, high-affinity complexes with GDI that need to be disrupted for membrane attachment and targeting of Rab proteins. The Legionella pneumophila protein DrrA displaces GDI from Rab1:GDI complexes, incorporating Rab1 into Legionella-containing vacuoles and activating Rab1 by exchanging GDP for GTP. Here, we present the crystal structure of a complex between the GEF domain of DrrA and Rab1 and a detailed kinetic analysis of this exchange. DrrA efficiently catalyzes nucleotide exchange and mimics the general nucleotide exchange mechanism of mammalian GEFs for Ras-like GTPases. We show that the GEF activity of DrrA is sufficient to displace prenylated Rab1 from the Rab1:GDI complex. Thus, apparent GDI displacement by DrrA is linked directly to nucleotide exchange, suggesting a basic model for GDI displacement and specificity of Rab localization that does not require discrete GDI displacement activity. RabGDI displacement by DrrA from Legionella is a consequence of its guanine nucleotide exchange activity.,Schoebel S, Oesterlin LK, Blankenfeldt W, Goody RS, Itzen A Mol Cell. 2009 Dec 25;36(6):1060-72. PMID:20064470[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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