Functional interplay of ribosome-associated chaperones & factors
In order to carry out any specific biological function, proteins first have to adopt a particular three-dimensional native structure by folding. In vivo especially the initial folding process of newly synthesized polypeptides is decisive for productive structure formation. Therefore, a set of diverse but conserved chaperones directly associates with the translating ribosomes to act on emerging nascent polypeptides and to support co-translational folding processes. To uncover basic mechanisms of co-translational protein folding, I will investigate (i) the structure acquisition of ribosome-attached nascent polypeptides on a molecular level, (ii) the impact of ribosome-bound chaperones on this process, and (iii) compare co-translational protein folding in eu- and prokaryotic kingdoms of life in order to reveal differences and/or similarities. For this purpose, I am developing a method to generate and purify quantitative amounts of homogenous populations of ribosome-nascent chain complexes (RNCs), which are stalled at a particular stage during translation of model polypeptides in vivo. These complexes will be used to study nascent chains and the influence of ribosome-associated chaperones on their initial folding.
- Preißler, Steffen - Project leader
- Department of Biology
| (2010): Cotranslational structure acquisition of nascent polypeptides monitored by NMR spectroscopy Proceedings of the National Academy of Sciences of the United States of America. 2010, 107(20), pp. 9111-9116. ISSN 0027-8424. eISSN 1091-6490. Available under: doi: 10.1073/pnas.0914300107 |
The folding of proteins in living cells may start during their synthesis when the polypeptides emerge gradually at the ribosomal exit tunnel. However, our current understanding of cotranslational folding processes at the atomic level is limited. We employed NMR spectroscopy to monitor the conformation of the SH3 domain from α-spectrin at sequential stages of elongation via in vivo ribosome-arrested 15N,13C-labeled nascent polypeptides. These nascent chains exposed either the entire SH3 domain or C-terminally truncated segments thereof, thus providing snapshots of the translation process. We show that nascent SH3 polypeptides remain unstructured during elongation but fold into a compact, native-like β-sheet assembly when the entire sequence information is available. Moreover, the ribosome neither imposes major conformational constraints nor significantly interacts with exposed unfolded nascent SH3 domain moieties. Our data provide evidence for a domainwise folding of the SH3 domain on ribosomes without significant population of folding intermediates. The domain follows a thermodynamically favorable pathway in which sequential folding units are stabilized, thus avoiding kinetic traps during the process of cotranslational folding. Origin (projects) |
| Name | Finanzierungstyp | Kategorie | Project no. |
|---|---|---|---|
| Exzellenzinitiative | third-party funds | research funding program | 510/09 |
| Period: | since 31.12.2010 |