Московский семинар по биоинформатике Инна Поволоцкая «Стоп-кодоны в бактериях не эквивалентны с точки зрения обзора»

15 декабря 2011 г., Москва

Рубрики: Семинар | Биотехнологии

URL мероприятия: http://www.rtcb.iitp.ru/msb/Index.htm

Описание:

Четверг, 15 декабря 2011 года, 17:00, Москва, Институт молекулярной биологии им. Энгельгардта, 3-й этаж, конференц-зал.

Тема заседания — доклад Инны Поволоцкой, Centre for Genomic Regulation, Barcelona;
«Стоп-кодоны в бактериях не эквивалентны с точки зрения обзора»)

Many global patterns in molecular evolution are defined by the genetical code, including rates of nonsynonymous and synonymous evolution, synonymous codon usage and the optimality of the genetic code. The evolution and usage of stop codons, however, have not been rigorously studied with the exception of coding of non-canonical amino acids. Here, we study the rate of evolution and genomic frequency of TAA, TGA and TAG canonical stop codons in bacterial genomes. We find that stop codons evolve slower than synonymous sites, suggesting the action of weak negative selection. However, the frequency of stop codon usage relative to genomic nucleotide content indicates that this selection regime is not straightforward. The usage of TAA and TGA stop codons is GC-content dependent, with TAA decreasing and TGA increasing with GC content, while TAG frequency is independent of nucleotide content. We thus modeled stop codon usage and nucleotide content with mutation rates and two selection on nucleotide content and TAG frequency as parameters. We found that the relationship between stop codon frequencies and nucleotide content cannot be explained by mutational biases or selection on nucleotide content. However, with weak nucleotide content-dependent selection on TAG, -0.5 < Nes < 1.5, the model fits all of the data and recapitulates the lack of a relationship of TAG and nucleotide content. For biologically plausible rates of mutations we show that, in bacteria, TAG stop codon is universally associated with lower fitness, with TAA being the optimal stop codon for G-content < 16% while for G-content > 16% TGA has a higher fitness than TAG.

Рабочий язык семинара — английский (и русский).

Адрес:
Москва, ул. Вавилова, 32, Институт молекулярной биологии им. Энгельгардта (ИМБ РАН), 3-й этаж, конференц-зал.
Проезд: станция метро «Университет» или «Ленинский проспект», далее трамваями № 14 или № 39 до остановки «Ул. Ляпунова» или «Ул. Бардина».

Схема проезда: Институт молекулярной биологии РАН (схема проезда)

Источник информации: http://elementy.ru/