5l3r
Structure of the GTPase heterodimer of chloroplast SRP54 and FtsY from Arabidopsis thaliana
Structural highlights
FunctionSR54C_ARATH Involved in cotranslational and post-translational sorting of thylakoid proteins. Binds GTP specifically. Activates the GTPase activity of CPFTSY when bound together. Required for light-harvesting chlorophyll a/b-binding protein (LHCP) integration into thylakoids.[1] [2] [3] [4] Publication Abstract from PubMedThe signal recognition particle (SRP) is a ribonucleoprotein complex with a key role in targeting and insertion of membrane proteins. The two SRP GTPases, SRP54 (Ffh in bacteria) and FtsY (SRalpha in eukaryotes), form the core of the targeting complex (TC) regulating the SRP cycle. The architecture of the TC and its stimulation by RNA has been described for the bacterial SRP system while this information is lacking for other domains of life. Here, we present the crystal structures of the GTPase heterodimers of archaeal (Sulfolobus solfataricus), eukaryotic (Homo sapiens), and chloroplast (Arabidopsis thaliana) SRP systems. The comprehensive structural comparison combined with Brownian dynamics simulations of TC formation allows for the description of the general blueprint and of specific adaptations of the quasi-symmetric heterodimer. Our work defines conserved external nucleotide-binding sites for SRP GTPase activation by RNA. Structural analyses of the GDP-bound, post-hydrolysis states reveal a conserved, magnesium-sensitive switch within the I-box. Overall, we provide a general model for SRP cycle regulation by RNA. Structural Basis for Conserved Regulation and Adaptation of the Signal Recognition Particle Targeting Complex.,Wild K, Bange G, Motiejunas D, Kribelbauer J, Hendricks A, Segnitz B, Wade RC, Sinning I J Mol Biol. 2016 May 27. pii: S0022-2836(16)30184-X. doi:, 10.1016/j.jmb.2016.05.015. PMID:27241309[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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