SCIENCE AT THE EDGE SEMINAR
QBI/GEDD
Friday, January 15 at 11:30am
Room 1400 Biomedical and Physical Sciences Bldg.
Refreshments at 11:15
Claus O. Wilke
Section of Integrative Biology and Center for Computational Biology and Bioinformatics, University of Texas at Austin
Selection for Accurate and Efficient Gene Expression
All cellular life depends on accurate and efficient expression of genes. Widely diverged organisms, from bacteria to vertebrates, experience similar selection pressures related to protein biosynthesis.
(These selection pressures are often referred to as "translational selection".) I will present evidence for widespread occurrence of two different types of translational selection. First, I will discuss selection for translational accuracy. Synonymous codons
differ in their translational error rates. Thus, the accuracy with which a gene is translated can be influenced by the codon usage bias of the gene. I will present evidence that codon usage is site-specific, such that more sensitive sites are encoded with
codons that have reduced error rate. Thus, translational accuracy is increased at sites at which translation errors would be particularly harmful. Second, I will discuss selection for efficient translation initiation. Experimental work in E. coli has shown
that strong mRNA secondary structure can interfere with efficient translation initiation. Motivated by this finding, we carried out a computational assesment of mRNA stability near the translation initiation site in over 340 complete genomes. We found that
mRNA stability is generally reduced near the start codon in all three kingdoms of life. In prokaryotes, the strength of the effect correlates positively with genome GC content and negatively with the optimal growing temperature of the organism.
Helen Geiger
Administrative Assistant
Quantitative Biology Initiative/
Gene Expression in Development & Disease
Michigan State University
502B Biochemistry Building
East Lansing, MI 48824
Phone: (517) 432-9895
Fax: (517) 353-9334
Web:
http://qbmi.msu.edu
http://www.bch.msu.edu/GEDD/index.htm