Взаимодействие тмРНК с рибосомой в процессе транс-трансляции

выводы.

1. Во всех выделенных тмРНК с рибосомой, в которых транс-трансляция остановлена на различных этапах, присутствует белок SmpB. Стехиометрия комплексов рибосома-тмРНК-SmpB равна 1:1:1 на всех стадиях транс-трансляции. Белок SmpB занимает канонический сайт связывания с тРНК-подобным доменом тмРНК.

2. Псевдоузел 3 тмРНК находится на поверхности рибосомы на всех этапах транстрансляции.

3. Псевдоузлы 2, 3 и 4 образуют петлю на поверхности 70S рибосомы. Эта петля подвижна в растворе и может занимать различные положения от «плеча» до вершины «головы» 30S субчастицы рибосомы. Положения концов данной петли тмРНК на рибосоме соответствуют входу и выходу канала мРНК, предполагая размещение в нем мРИК-подобной части тмРНК.

4. Структура и контакты тмРНК, за исключением мРНК-подобного домена и спирали 5, практически не изменяются в ходе транс-трансляции. Спираль 5 стабилизируется или защищается при взаимодействии тмРНК с рибосомой. Спектр модификаций нуклеотидов мРНК-подобного домена изменяется по мере прохождения тмРНК через рибосому в ходе транс-трансляции.

5. Изменения последовательности в мРНК-подобном домене тмРНК влияют на реакционную способность нуклеотидов в спирали 2, что предполагает существование третичного контакта между этими областями.

6. Полученные данные позволили предложить механизм прохождения тмРНК через рибосому в ходе транс-трансляции.

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