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Studies on the bacteriophage MS2. XXII. Conformation of MS2 RNA in acid medium
Author(s) -
Slegers H.,
Fiers W.
Publication year - 1973
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1973.360120908
Subject(s) - protonation , chemistry , rna , monomer , ionic strength , ionic bonding , bacteriophage ms2 , crystallography , ion , polymer chemistry , polymer , biochemistry , organic chemistry , coat protein , aqueous solution , gene
MS2 RNA, which sediments at 27S in a neutral buffer, can be converted to a compact 57S conformation at pH 3.8. Requirements for this conversion, besides protonation, are small concentrations of Mg ++ ions and a low ionic strength. On the other hand, after heating in the presence of EDTA and at low ionic strength, the RNA can be unfolded to an 11.7S form at pH 6.8 and to 10.5S at pH 3.8. The compact 57S form has lost at least 50% of its secondary structure, as determined by its hypochromicity. It corresponds to a monomer species, as will be shown in a following paper (XXIV). Comparative studies with the homopolymers poly A and poly C and with the heteropolymers poly A,U, poly A,C, and poly A,G indicate that the interactions involved in the acid RNA conformation are not simply explainable by the known interactions of the A–A + , C–C + , and/or A–C + type.