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The conformation of a nascent polypeptide inside the ribosome tunnel affects protein targeting and protein folding
Author(s) -
Peterson Janine H.,
Woolhead Cheryl A.,
Bernstein Harris D.
Publication year - 2010
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2010.07325.x
Subject(s) - biology , ribosome , ribosomal protein , signal peptide , protein folding , biochemistry , signal recognition particle , escherichia coli , ribosome biogenesis , microbiology and biotechnology , biophysics , peptide sequence , rna , gene
Summary In this report, we describe insights into the function of the ribosome tunnel that were obtained through an analysis of an unusual 25 residue N‐terminal motif (EspP 1‐25 ) associated with the signal peptide of the Escherichia coli EspP protein. It was previously shown that EspP 1‐25 inhibits signal peptide recognition by the signal recognition particle, and we now show that fusion of EspP 1‐25 to a cytoplasmic protein causes it to aggregate. We obtained two lines of evidence that both of these effects are attributable to the conformation of EspP 1‐25 inside the ribosome tunnel. First, we found that mutations in EspP 1‐25 that abolished its effects on protein targeting and protein folding altered the cross‐linking of short nascent chains to ribosomal components. Second, we found that a mutation in L22 that distorts the tunnel mimicked the effects of the EspP 1‐25 mutations on protein biogenesis. Our results provide evidence that the conformation of a polypeptide inside the ribosome tunnel can influence protein folding under physiological conditions and suggest that ribosomal mutations might increase the solubility of at least some aggregation‐prone proteins produced in E. coli .