3bbu
The Hsp15 protein fitted into the low resolution Cryo-EM map of the 50S.nc-tRNA.Hsp15 complexThe Hsp15 protein fitted into the low resolution Cryo-EM map of the 50S.nc-tRNA.Hsp15 complex
Structural highlights
Function[HSLR_ECOLI] Involved in the recycling of free 50S ribosomal subunits that still carry a nascent chain. Binds RNA more specifically than DNA. Binds with very high affinity to the free 50S ribosomal subunit. Does not bind it when it is part of the 70S ribosome. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedWhen heat shock prematurely dissociates a translating bacterial ribosome, its 50S subunit is prevented from reinitiating protein synthesis by tRNA covalently linked to the unfinished protein chain that remains threaded through the exit tunnel. Hsp15, a highly upregulated bacterial heat shock protein, reactivates such dead-end complexes. Here, we show with cryo-electron microscopy reconstructions and functional assays that Hsp15 translocates the tRNA moiety from the A site to the P site of stalled 50S subunits. By stabilizing the tRNA in the P site, Hsp15 indirectly frees up the A site, allowing a release factor to land there and cleave off the tRNA. Such a release factor must be stop codon independent, suggesting a possible role for a poorly characterized class of putative release factors that are upregulated by cellular stress, lack a codon recognition domain and are conserved in eukaryotes. Recycling of aborted ribosomal 50S subunit-nascent chain-tRNA complexes by the heat shock protein Hsp15.,Jiang L, Schaffitzel C, Bingel-Erlenmeyer R, Ban N, Korber P, Koning RI, de Geus DC, Plaisier JR, Abrahams JP J Mol Biol. 2009 Mar 13;386(5):1357-67. Epub 2008 Nov 5. PMID:19013177[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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