2AKH

Normal mode-based flexible fitted coordinates of a non-translocating SecYEG protein-conducting channel into the cryo-EM map of a SecYEG-nascent chain-70S ribosome complex from E. coli

Summary for 2AKH

• Entry DOI: 10.2210/pdb2akh/pdb
• Related: 2AKI
• EMDB information: 1143
• Descriptor: Protein-export membrane protein secG, Preprotein translocase secY subunit, Preprotein translocase secE subunit (3 entities in total)
• Functional Keywords: protein transport, translocation, transmembrane, transport
• Biological source: Escherichia coli; More
• Total number of polymer chains: 6
• Total formula weight: 127926.18

Authors

Mitra, K.M.,Schaffitzel, C.,Shaikh, T.,Tama, F.,Jenni, S.,Brooks III, C.L.,Ban, N.,Frank, J. (deposition date: 2005-08-03, release date: 2005-11-15, Last modification date: 2024-02-14)

Primary citation

Mitra, K.,Schaffitzel, C.,Shaikh, T.,Tama, F.,Jenni, S.,Brooks, C.L.,Ban, N.,Frank, J.
Structure of the E. coli protein-conducting channel bound to a translating ribosome.
Nature, 438:318-324, 2005

PubMed Abstract: Secreted and membrane proteins are translocated across or into cell membranes through a protein-conducting channel (PCC). Here we present a cryo-electron microscopy reconstruction of the Escherichia coli PCC, SecYEG, complexed with the ribosome and a nascent chain containing a signal anchor. This reconstruction shows a messenger RNA, three transfer RNAs, the nascent chain, and detailed features of both a translocating PCC and a second, non-translocating PCC bound to mRNA hairpins. The translocating PCC forms connections with ribosomal RNA hairpins on two sides and ribosomal proteins at the back, leaving a frontal opening. Normal mode-based flexible fitting of the archaeal SecYEbeta structure into the PCC electron microscopy densities favours a front-to-front arrangement of two SecYEG complexes in the PCC, and supports channel formation by the opening of two linked SecY halves during polypeptide translocation. On the basis of our observation in the translocating PCC of two segregated pores with different degrees of access to bulk lipid, we propose a model for co-translational protein translocation.

PubMed: 16292303
DOI: 10.1038/nature04133

Experimental method

ELECTRON MICROSCOPY (14.9 Å)