2n62
From Proteopedia
ddFLN5+110
Structural highlights
FunctionGELA_DICDI F-actin cross-linking protein.SECM_ECOLI Regulates secA expression by translational coupling of the secM secA operon. Ribosomes translating the C-terminal region of secM can disrupt an RNA repressor helix that normally blocks secA translation initiation, derepressing the expression of secA. Translational pausing of secM at Pro-166 under secretion-limiting conditions increases the duration of the disruption and thus increases secA expression. This is controlled by interaction of the secM signal peptide with secA and the translocon, possibly by secA pulling the paused secM out of the ribosome. The arrest sequence (150-FXXXXWIXXXXGIRAGP-166) is sufficient to cause arrest of unrelated proteins. Elongation arrest can be alleviated by mutations in the 23S rRNA or in ribosomal protein L22. Publication Abstract from PubMedAlthough detailed pictures of ribosome structures are emerging, little is known about the structural and cotranslational folding properties of nascent polypeptide chains at the atomic level. Here we used solution-state NMR spectroscopy to define a structural ensemble of a ribosome-nascent chain complex (RNC) formed during protein biosynthesis in Escherichia coli, in which a pair of immunoglobulin-like domains adopts a folded N-terminal domain (FLN5) and a disordered but compact C-terminal domain (FLN6). To study how FLN5 acquires its native structure cotranslationally, we progressively shortened the RNC constructs. We found that the ribosome modulates the folding process, because the complete sequence of FLN5 emerged well beyond the tunnel before acquiring native structure, whereas FLN5 in isolation folded spontaneously, even when truncated. This finding suggests that regulating structure acquisition during biosynthesis can reduce the probability of misfolding, particularly of homologous domains. A structural ensemble of a ribosome-nascent chain complex during cotranslational protein folding.,Cabrita LD, Cassaignau AM, Launay HM, Waudby CA, Wlodarski T, Camilloni C, Karyadi ME, Robertson AL, Wang X, Wentink AS, Goodsell LS, Woolhead CA, Vendruscolo M, Dobson CM, Christodoulou J Nat Struct Mol Biol. 2016 Apr;23(4):278-85. doi: 10.1038/nsmb.3182. Epub 2016 Feb, 29. PMID:26926436[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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