3ZN8

Structural Basis of Signal Sequence Surveillance and Selection by the SRP-SR Complex

Summary for 3ZN8

• Entry DOI: 10.2210/pdb3zn8/pdb
• EMDB information: 2316
• Descriptor: SIGNAL RECOGNITION PARTICLE PROTEIN, SIGNAL RECOGNITION PARTICLE RECEPTOR FTSY, 4.5 S RNA, ... (7 entities in total)
• Functional Keywords: protein transport, hydrolase
• Biological source: ESCHERICHIA COLI; More
• Total number of polymer chains: 5
• Total formula weight: 109082.64

Authors

von Loeffelholz, O.,Knoops, K.,Ariosa, A.,Zhang, X.,Karuppasamy, M.,Huard, K.,Schoehn, G.,Berger, I.,Shan, S.O.,Schaffitzel, C. (deposition date: 2013-02-13, release date: 2013-03-06, Last modification date: 2024-05-08)

Primary citation

Von Loeffelholz, O.,Knoops, K.,Ariosa, A.,Zhang, X.,Karuppasamy, M.,Huard, K.,Schoehn, G.,Berger, I.,Shan, S.O.,Schaffitzel, C.
Structural Basis of Signal Sequence Surveillance and Selection by the Srp-Sr Complex
Nat.Struct.Mol.Biol., 20:604-, 2013

PubMed Abstract: Signal-recognition particle (SRP)-dependent targeting of translating ribosomes to membranes is a multistep quality-control process. Ribosomes that are translating weakly hydrophobic signal sequences can be rejected from the targeting reaction even after they are bound to the SRP. Here we show that the early complex, formed by Escherichia coli SRP and its receptor FtsY with ribosomes translating the incorrect cargo EspP, is unstable and rearranges inefficiently into subsequent conformational states, such that FtsY dissociation is favored over successful targeting. The N-terminal extension of EspP is responsible for these defects in the early targeting complex. The cryo-electron microscopy structure of this 'false' early complex with EspP revealed an ordered M domain of SRP protein Ffh making two ribosomal contacts, and the NG domains of Ffh and FtsY forming a distorted, flexible heterodimer. Our results provide a structural basis for SRP-mediated signal-sequence selection during recruitment of the SRP receptor.

PubMed: 23563142
DOI: 10.1038/NSMB.2546

Experimental method

ELECTRON MICROSCOPY (12 Å)