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Moradi, Hossein
Publications (4 of 4) Show all publications
Simoff, I., Moradi, H. & Nygård, O. (2009). Functional characterization of ribosomal protein L15 from Saccharomyces cerevisiae. Current Genetics, 55(2), 111-125
Open this publication in new window or tab >>Functional characterization of ribosomal protein L15 from Saccharomyces cerevisiae
2009 (English)In: Current Genetics, ISSN 0172-8083, E-ISSN 1432-0983, Vol. 55, no 2, p. 111-125Article in journal (Refereed) Published
Abstract [en]

In this study we provide general information on the little studied eukaryotic ribosomal protein rpL15. Saccharomyces cerevisiae has two genes, YRPL15A and YRPL15B that could potentially code for yeast rpL15 (YrpL15). YRPL15A is essential while YRPL15B is dispensable. However, a plasmid-borne copy of the YRPL15B gene, controlled by the GAL1 promoter or by the promoter controlling expression of the YRPL15A gene, can functionally complement YrpL15A in yeast cells, while the same gene controlled by the authentic promoter is inactive. Analysis of the levels of YrpL15B-mRNA in yeast cells shows that the YRPL15B gene is inactive in transcription. The function of YrpL15A is highly resilient to single and multiple amino acid substitutions. In addition, minor deletions from both the N- and C-terminal ends of YrpL15A has no effect on protein function, while addition of a C-terminal tag that could be used for detection of plasmid-encoded YrpL15A is detrimental to protein function. YrpL15A could also be replaced by the homologous protein from Arabidopsis thaliana despite almost 30% differences in the amino acid sequence, while the more closely related protein from Schizosaccharomyces pombe was inactive. The lack of function was not caused by a failure of the protein to enter the yeast nucleus.

National Category
Genetics
Identifiers
urn:nbn:se:sh:diva-13904 (URN)10.1007/s00294-009-0228-z (DOI)000265092000002 ()2-s2.0-67349272028 (Scopus ID)
Available from: 2011-12-14 Created: 2011-12-14 Last updated: 2017-12-08Bibliographically approved
Moradi, H., Simoff, I., Bartish, G. & Nygård, O. (2008). Functional features of the C-terminal region of yeast ribosomal protein L5. Molecular Genetics and Genomics, 280(4), 337-350
Open this publication in new window or tab >>Functional features of the C-terminal region of yeast ribosomal protein L5
2008 (English)In: Molecular Genetics and Genomics, ISSN 1617-4615, E-ISSN 1617-4623, Vol. 280, no 4, p. 337-350Article 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.

National Category
Biochemistry and Molecular Biology Genetics
Identifiers
urn:nbn:se:sh:diva-14121 (URN)10.1007/s00438-008-0369-7 (DOI)000258902300007 ()18751732 (PubMedID)2-s2.0-51349101530 (Scopus ID)
Available from: 2011-12-18 Created: 2011-12-16 Last updated: 2017-12-08Bibliographically approved
Bartish, G., Moradi, H. & Nygård, O. (2007). Amino acids Thr56 and Thr58 are not essential for elongation factor 2 function in yeast. The FEBS Journal, 274(20), 5285-5297
Open this publication in new window or tab >>Amino acids Thr56 and Thr58 are not essential for elongation factor 2 function in yeast
2007 (English)In: The FEBS Journal, ISSN 1742-464X, E-ISSN 1742-4658, Vol. 274, no 20, p. 5285-5297Article in journal (Refereed) Published
Abstract [en]

Yeast elongation factor 2 is an essential protein that contains two highly conserved threonine residues, T56 and T58, that could potentially be phosphorylated by the Rck2 kinase in response to environmental stress. The importance of residues T56 and T58 for elongation factor 2 function in yeast was studied using site directed mutagenesis and functional complementation. Mutations T56D, T56G, T56K, T56N and T56V resulted in nonfunctional elongation factor 2 whereas mutated factor carrying point mutations T56M, T56C, T56S, T58S and T58V was functional. Expression of mutants T56C, T56S and T58S was associated with reduced growth rate. The double mutants T56M/T58W and T56M/T58V were also functional but the latter mutant caused increased cell death and considerably reduced growth rate. The results suggest that the physiological role of T56 and T58 as phosphorylation targets is of little importance in yeast under standard growth conditions. Yeast cells expressing mutants T56C and T56S were less able to cope with environmental stress induced by increased growth temperatures. Similarly, cells expressing mutants T56M and T56M/T58W were less capable of adapting to increased osmolarity whereas cells expressing mutant T58V behaved normally. All mutants tested were retained their ability to bind to ribosomes in vivo. However, mutants T56D, T56G and T56K were under-represented on the ribosome, suggesting that these nonfunctional forms of elongation factor 2 were less capable of competing with wild-type elongation factor 2 in ribosome binding. The presence of nonfunctional but ribosome binding forms of elongation factor 2 did not affect the growth rate of yeast cells also expressing wild-type elongation factor 2.

National Category
Cell Biology
Identifiers
urn:nbn:se:sh:diva-14205 (URN)10.1111/j.1742-4658.2007.06054.x (DOI)000249882400009 ()17892487 (PubMedID)2-s2.0-34848907218 (Scopus ID)
Available from: 2011-12-20 Created: 2011-12-19 Last updated: 2017-12-08Bibliographically approved
Simoff, I., Moradi, H. & Nygård, O.Implications of N-terminal sequence elements in S. cerevisiae ribosomal protein L5.
Open this publication in new window or tab >>Implications of N-terminal sequence elements in S. cerevisiae ribosomal protein L5
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Yeast ribosomal protein L5 (YrpL5) is an essential 5S rRNA-binding protein that forms the central protuberance of the large ribosomal subunit. Formation of the binary rpL5.5S rRNA complex is a prerequisite for nuclear import of rpL5 and for ribosome assembly. The involvment of the N-terminal sequences of YrpL5 in 5S rRNA interaction and nuclear import was studied by mutagenesis and functional complementation in S. cerevisiae. Furthermore, the ability of YrpL5 orthologous proteins from M. musculus (MrpL5), D. melanogaster (DrpL5) and A. thaliana (ArpL5) were non-functional in yeast cells. Nuclear import of YrpL5 requires conserved sequence elements in the N-terminus. Despite the presence of these elements in ArpL5, this protein was not recognized by the nuclear import machinery in yeast. This failure was probably due to lack of stable complex formation with yeast 5S rRNA.

Keywords
Functional complementation, Mutation analysis, Ribosomal protein L5, nuclear localization, S. cerevisiae
National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:sh:diva-30700 (URN)
Note

Som manuskript i avhandling. As manuscript in dissertation.

Available from: 2009-05-14 Created: 2016-08-05 Last updated: 2016-08-05Bibliographically approved
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