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Functional features of the C-terminal region of yeast ribosomal protein L5
Södertörn University, School of Life Sciences.
Södertörn University, School of Life Sciences.
Södertörn University, School of Life Sciences.
Södertörn University, School of Life Sciences.
2008 (English)In: Molecular Genetics and Genomics, ISSN 1617-4615, E-ISSN 1617-4623, Vol. 280, no 4, 337-350 p.Article in journal (Refereed) Published
Abstract [en]

The aim of this study was to analyze the functional importance of the C-terminus of the essential yeast ribosomal protein L5 (YrpL5). Previous studies have indicated that the C-terminal region of YrpL5 forms an alpha-helix with a positively charged surface that is involved in protein-5S rRNA interaction. Formation of an YrpL5 center dot 5S rRNA complex is a prerequisite for nuclear import of YrpL5. Here we have tested the importance of the alpha-helix and the positively charged surface for YrpL5 function in Saccharomyces cerevisiae using site directed mutagenesis in combination with functional complementation. Alterations in the sequence forming the putative alpha-helix affected the functional capacity of YrpL5. However, the effect did not correlate with a decreased ability of the protein to bind to 5S rRNA as all rpL5 mutants tested were imported to the nucleus whether or not the alpha-helix or the positively charged surface were intact. The alterations introduced in the C-terminal sequence affected the growth rate of cells expressing mutant but functional forms of YrpL5. The reduced growth rate was correlated with a reduced ribosomal content per cell indicating that the alterations introduced in the C-terminus interfered with ribosome assembly.

Place, publisher, year, edition, pages
2008. Vol. 280, no 4, 337-350 p.
National Category
Biochemistry and Molecular Biology Genetics
Identifiers
URN: urn:nbn:se:sh:diva-14121DOI: 10.1007/s00438-008-0369-7ISI: 000258902300007PubMedID: 18751732ScopusID: 2-s2.0-51349101530OAI: oai:DiVA.org:sh-14121DiVA: diva2:467049
Available from: 2011-12-18 Created: 2011-12-16 Last updated: 2016-08-05Bibliographically approved
In thesis
1. Ribosomal proteins L5 and L15: Functional characterisation of important features, in vivo
Open this publication in new window or tab >>Ribosomal proteins L5 and L15: Functional characterisation of important features, in vivo
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Protein synthesis is a highly regulated and energy consuming process, during which a large ribonucleoprotein particle called the ribosome, synthesizes new proteins. The eukaryotic ribosome consists of two unequal subunits called: small and large subunits. Both subunits are composed of ribosomal RNA (rRNA) and ribosomal proteins (r-proteins).

Although rRNAs build the matrix of the ribosome and carries out catalysing of the peptide-bond formation between amino acids, r-proteins also appear to play important structural and functional roles. The primary role of r-proteins is to initiate the correct tertiary fold of rRNA and to organize the overall structure of the ribosome.

In this thesis, I focus on two proteins from the large subunit of the eukaryotic ribosome: r-proteins L5 and L15 from bakers yeast S. cerevisiae. Both r-proteins are essential for ribosome function. Their life cycle is primarily associated with rRNA interactions. As a consequence, the proteins show high sequence homology across the species borders. Furthermore, both L5 and L15 are connected to human diseases, which makes the study their role in ribosome biogenesis and ribosome function important.

By applying random- and site-directed mutagenesis, coupled with functional complementation tests, I aimed to elucidate functionally regions in both proteins, implicated in transport to the cell nucleus, protein-protein interactions and/or rRNA binding. The importance of individual and multiple amino acid exchanges in the primary sequence of rpL5 and rpL15 were studied in vivo. The obtained results show that S. cerevisiae rpL15 was tolerant to amino acid exchanges in the primary sequence, whereas rpL5 was not. Consequently, A. thaliana rpL15 could substitute for the function of wild type rpL15, whereas none of the tested orthologous proteins to rpL5 could substitute yeast rpL5 in vivo. These observations further emphasize the importance of studying r-proteins as separate entities in the ribosome context.

Place, publisher, year, edition, pages
Stockholm: Stockholm University, 2009. 50 p.
National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:sh:diva-30701 (URN)978-91-7155-896-1 (ISBN)
Public defence
2009-06-16, MB 503, Södertörns högskola, Alfred Nobels allé 7, 10:00 (English)
Opponent
Supervisors
Available from: 2016-08-05 Created: 2016-08-05 Last updated: 2016-08-05Bibliographically approved

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