Enzymatic activity of the ribosome‐bound nascent polypeptide

Abstract

tide extended by 1 to 59 amino acid residues at the C-terminus and still attached to the ribosome. The ribosomes bearing those elongated luciferases were isolated and the enzyme activity assay revealed that the nascent luciferase was enzymatically active if the C-terminus has been extended by 26, 27, 31, 42 and 59 extra amino acid residues. Extensions by 1, 12 or 21 residues were not enough for the ribosome-bound nascent enzyme to attain its active conformation.These results were first reported at the conference 'Frontiers in Translation', Victoria, B.C., Canada, May 20-25, 1995 (see [16]). The principal result was reproduced by another group with another enzyme, rhodanese [17].

Flexibility of the nascent polypeptide chain within the ribosome

“…This underscores the high degree of flexibility in the naagainst antibodies to each of the 21 30S proteins by the method scent peptide which, as noted above, is consistent with the conof Gulle et al [25]. The results confirmed the preliminary analy-cept of co-translational folding [5,6]. Co-translational folding sis and showed that the proteins involved were S1, S2, S4 and, also implies that the ribosomal tunnel must be wide enough to to a lesser extent, S3.…”

“…In our own experiments in this area, we have attempted peptides) were considered in the cross-link analyses. Thus, the to define the path followed by the nascent peptide through the nascent peptide is clearly very flexible within the ribosomal tunnel, a property which would be expected if co-translational foldCorrespondence to R. Brimacombe, Max-Planck-Institut für Mole-ing [5,6] is to occur, since the peptide must be able to continu- …”

“…Secondly, there is the question of co-transla-of peptides of 30 amino acids or longer became cross-linked to a site on the 23S rRNA in the direct neighbourhood of sites that tional folding, that is to say the extent to which the peptide can already attain its final folded conformation within the ribosome had been previously cross-linked to L23 and L29 [13], proteins which, in turn, had been located by immune electron microscopy e.g. [5,6]. A third aspect is the regulatory influence of the na- [14] at positions close to the proposed exit site [9], mentioned scent peptide on the translation of its own mRNA (reviewed in above.…”

“…In our own experiments in this area, we have attempted peptides) were considered in the cross-link analyses. Thus, the to define the path followed by the nascent peptide through the nascent peptide is clearly very flexible within the ribosomal tunnel, a property which would be expected if co-translational foldCorrespondence to R. Brimacombe, Max-Planck-Institut für Mole-ing [5,6] is to occur, since the peptide must be able to continu- served that, in some cases, the flexibility of the nascent peptide is so pronounced that the N-terminal region can even become cross-linked to the 30S subunit [12]. This cross-linking was not, however, characterized in the latter publication, which was solely concerned with the analysis of the cross-links to 23S rRNA from the three peptide families under investigation ; the characterization of the cross-linking to the 30S subunit is the subject of this paper.…”

Age-Related Macular Degeneration-Associated Silent Polymorphisms in HtrA1 Impair Its Ability To Antagonize Insulin-Like Growth Factor 1

“…In vivo, folding of nascent proteins proceeds cotranslationally (10,11) and is influenced by the rate of ribosome transit through the mRNA template. What distinguishes synonymous codons that encode a given degenerate amino acid is the abundance of their corresponding tRNA, which is lower for infrequently used codons than for frequently used codons (12,13).…”