1RJ9

Structure of the heterodimer of the conserved GTPase domains of the Signal Recognition Particle (Ffh) and Its Receptor (FtsY)

Summary for 1RJ9

• Entry DOI: 10.2210/pdb1rj9/pdb
• Related: 1DUH 1DUL 1FFH 1JPJ 1JPN 1LS1 1NG1 1O87 1OKK 2FFH 2NG1 3NG1
• Descriptor: Signal Recognition Protein, Signal recognition particle protein, MAGNESIUM ION, ... (5 entities in total)
• Functional Keywords: srp-gtpase domain, heterodimer, nucleotide twinning, protein-protein complex, protein transport
• Biological source: Thermus aquaticus; More
• Cellular location: Cell inner membrane; Peripheral membrane protein (By similarity): P83749
• Total number of polymer chains: 2
• Total formula weight: 67057.39

Authors

Egea, P.F.,Shan, S.O.,Napetschnig, J.,Savage, D.F.,Walter, P.,Stroud, R.M. (deposition date: 2003-11-18, release date: 2004-01-27, Last modification date: 2024-04-03)

Primary citation

Egea, P.F.,Shan, S.O.,Napetschnig, J.,Savage, D.F.,Walter, P.,Stroud, R.M.
Substrate twinning activates the signal recognition particle and its receptor
Nature, 427:215-221, 2004

PubMed Abstract: Signal sequences target proteins for secretion from cells or for integration into cell membranes. As nascent proteins emerge from the ribosome, signal sequences are recognized by the signal recognition particle (SRP), which subsequently associates with its receptor (SR). In this complex, the SRP and SR stimulate each other's GTPase activity, and GTP hydrolysis ensures unidirectional targeting of cargo through a translocation pore in the membrane. To define the mechanism of reciprocal activation, we determined the 1.9 A structure of the complex formed between these two GTPases. The two partners form a quasi-two-fold symmetrical heterodimer. Biochemical analysis supports the importance of the extensive interaction surface. Complex formation aligns the two GTP molecules in a symmetrical, composite active site, and the 3'OH groups are essential for association, reciprocal activation and catalysis. This unique circle of twinned interactions is severed twice on hydrolysis, leading to complex dissociation after cargo delivery.

PubMed: 14724630
DOI: 10.1038/nature02250

Experimental method

X-RAY DIFFRACTION (1.9 Å)