Vl. Emerick et Sa. Woodson, FINGERPRINTING THE FOLDING OF A GROUP-I PRECURSOR RNA, Proceedings of the National Academy of Sciences of the United Statesof America, 91(21), 1994, pp. 9675-9679
Evidence that folding of the Tetrahymena pre-rRNA follows a defined pa
th and is rate-determining for splicing at physiological temperatures
is presented. Structural isomers were separated by native polyacrylami
de gel electrophoresis and their splicing activities were compared. GT
P binding selectively shifts the active form of the pre RNA to an elec
trophoretic band containing both spliced and unspliced RNA. In situ ch
emical modification provides evidence for base-pair rearrangements in
the 5' exon and structural. alterations in the intron core of partiall
y and fully active forms. Transition to the fully active precursor req
uires high temperature, but the activation energy is lower than expect
ed for opening of RNA helices. Implications for control of RNA conform
ation during splicing are discussed.