Structural highlights
Function
[SRP54_HUMAN] Binds to the signal sequence of presecretory protein when they emerge from the ribosomes and transfers them to TRAM (translocating chain-associating membrane protein). [SRPRA_HUMAN] Component of the SRP (signal recognition particle) receptor. Ensures, in conjunction with the signal recognition particle, the correct targeting of the nascent secretory proteins to the endoplasmic reticulum membrane system.
Publication Abstract from PubMed
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 (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[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Wild K, Bange G, Motiejunas D, Kribelbauer J, Hendricks A, Segnitz B, Wade RC, Sinning I. Structural Basis for Conserved Regulation and Adaptation of the Signal Recognition Particle Targeting Complex. J Mol Biol. 2016 May 27. pii: S0022-2836(16)30184-X. doi:, 10.1016/j.jmb.2016.05.015. PMID:27241309 doi:http://dx.doi.org/10.1016/j.jmb.2016.05.015
