Structural Basis for Conserved Regulation and Adaptation of the Signal Recognition Particle Targeting Complex. Issue 14 (17th July 2016)

• Record Type: Journal Article
• Authors: Wild, Klemens; Bange, Gert; Motiejunas, Domantas; Kribelbauer, Judith; Hendricks, Astrid; Segnitz, Bernd; Wade, Rebecca C.; Sinning, Irmgard
• Is Part Of: Journal of molecular biology. Volume 428:Issue 14(2016:Jul. 15)
• Page Start: 2880
• Page End: 2897
• Publication Date: 2016-07-17
• Subjects: SRP signal recognition particle -- RNCs ribosome–nascent chain complexes -- TC targeting complex -- cryo-EM cryo-electron microscopy -- FRET fluorescence resonance energy transfer -- GMPPNP 5′-Guanylyl-imidodiphosphate -- GMPPCP β, γ-Methyleneguanosine 5′-triphosphate -- nts nucleotides -- MTS membrane targeting sequence -- PR phosphoribose -- ESRF European synchrotron radiation facility; co-translational protein targeting -- ribonucleoprotein complex -- SRP GTPase -- X-ray structure analysis -- molecular modeling; Molecular biology -- Periodicals; Biology -- Periodicals; Biochemistry -- Periodicals; Bacteriology -- Periodicals; Molecular Biology -- Periodicals; Biochemistry -- Periodicals; Biologie moléculaire -- Périodiques; Biologie -- Périodiques; Biochimie -- Périodiques; Moleculaire biologie; Biochemistry; Biology; Molecular biology; Periodicals; 572.805
• DOI: 10.1016/j.jmb.2016.05.015
• Languages: English
• ISSNs: 0022-2836

Abstract

Abstract: The 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 (SRα 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. Graphical Abstract: Highlights: Protein targeting by the SRP TC formed by SRP54 and SRα GTPases X-ray structures of TCs for eukaryotes, archaea, and chloroplasts Comprehensive analysis of ligand binding and catalysis Inducible P-loop in the I-box allows for magnesium-sensitive conformational switch. Generalized model for RNA and protein mediated SRP GTPase activation