5L3Q

Structure of the GTPase heterodimer of human SRP54 and SRalpha

Summary for 5L3Q

• Entry DOI: 10.2210/pdb5l3q/pdb
• Descriptor: Signal recognition particle 54 kDa protein, Signal recognition particle receptor subunit alpha, SULFATE ION, ... (8 entities in total)
• Functional Keywords: co-translational protein targeting, signal recognition particle, gtpase, protein transport
• Biological source: Homo sapiens (Human); More
• Cellular location: Nucleus speckle : P61011; Endoplasmic reticulum membrane; Peripheral membrane protein: P08240
• Total number of polymer chains: 4
• Total formula weight: 242190.87

Authors

Wild, K.,Segnitz, B.,Sinning, I. (deposition date: 2016-05-24, release date: 2016-06-08, Last modification date: 2024-01-10)

Primary citation

Wild, K.,Bange, G.,Motiejunas, D.,Kribelbauer, J.,Hendricks, A.,Segnitz, B.,Wade, R.C.,Sinning, I.
Structural Basis for Conserved Regulation and Adaptation of the Signal Recognition Particle Targeting Complex.
J.Mol.Biol., 428:2880-2897, 2016

PubMed 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.

PubMed: 27241309
DOI: 10.1016/j.jmb.2016.05.015

Experimental method

X-RAY DIFFRACTION (3.2 Å)