4v4v | pdb_00004v4v
Structure of a pre-translocational E. coli ribosome obtained by fitting atomic models for RNA and protein components into cryo-EM map EMD-1056
Structural highlights
FunctionRL24_ECOLI One of two assembly initiator proteins, it binds directly to the 5'-end of the 23S rRNA, where it nucleates assembly of the 50S subunit. It is not thought to be involved in the functions of the mature 50S subunit in vitro.[1] One of the proteins that surrounds the polypeptide exit tunnel on the outside of the subunit.[2] Publication Abstract from PubMedIn E. coli, the SecM nascent polypeptide causes elongation arrest, while interacting with 23S RNA bases A2058 and A749-753 in the exit tunnel of the large ribosomal subunit. We compared atomic models fitted by real-space refinement into cryo-electron microscopy reconstructions of a pretranslocational and SecM-stalled E. coli ribosome complex. A cascade of RNA rearrangements propagates from the exit tunnel throughout the large subunit, affecting intersubunit bridges and tRNA positions, which in turn reorient small subunit RNA elements. Elongation arrest could result from the inhibition of mRNA.(tRNAs) translocation, E site tRNA egress, and perhaps translation factor activation at the GTPase-associated center. Our study suggests that the specific secondary and tertiary arrangement of ribosomal RNA provides the basis for internal signal transduction within the ribosome. Thus, the ribosome may itself have the ability to regulate its progression through translation by modulating its structure and consequently its receptivity to activation by cofactors. Elongation arrest by SecM via a cascade of ribosomal RNA rearrangements.,Mitra K, Schaffitzel C, Fabiola F, Chapman MS, Ban N, Frank J Mol Cell. 2006 May 19;22(4):533-43. PMID:16713583[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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