PDBsum entry 4c7o

Nuclear protein/RNA

PDB id: 4c7o

Contents

Protein chains

293 a.a.

271 a.a.

DNA/RNA

Ligands

ALF ×4

GDP ×5

Metals

_MG ×4

Waters ×501

References listed in PDB file

Key reference

• Title: The structural basis of ftsy recruitment and gtpase activation by srp RNA.
• Authors: F.Voigts-Hoffmann, N.Schmitz, K.Shen, S.O.Shan, S.F.Ataide, N.Ban.
• Ref.: Mol Cell, 2013, 52, 643-654. [DOI no: 10.1016/j.molcel.2013.10.005]
• PubMed id: 24211265

Abstract

The universally conserved signal recognition particle (SRP) system mediates the targeting of membrane proteins to the translocon in a multistep process controlled by GTP hydrolysis. Here we present the 2.6 Å crystal structure of the GTPase domains of the E. coli SRP protein (Ffh) and its receptor (FtsY) in complex with the tetraloop and the distal region of SRP-RNA, trapped in the activated state in presence of GDP:AlF4. The structure reveals the atomic details of FtsY recruitment and, together with biochemical experiments, pinpoints G83 as the key RNA residue that stimulates GTP hydrolysis. Insertion of G83 into the FtsY active site orients a single glutamate residue provided by Ffh (E277), triggering GTP hydrolysis and complex disassembly at the end of the targeting cycle. The complete conservation of the key residues of the SRP-RNA and the SRP protein implies that the suggested chemical mechanism of GTPase activation is applicable across all kingdoms.