Open AccessCorrelation of Structural Transitions in Coliphage R17 with its Loss of Infectivity
Author(s) -
Albert M. Bobst,
Elisabeth V. Bobst,
Dorothy J. Phillips
Publication year - 1976
Publication title -
journal of general virology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.55
H-Index - 167
eISSN - 1465-2099
pISSN - 0022-1317
DOI - 10.1099/0022-1317-32-2-177
Subject(s) - infectivity , biology , coliphage , virology , virus , bacteriophage , genetics , gene , escherichia coli
A circular dichroism comparative study of isolated and in situ phage R17 RNA reveals in both cases the same degree of base pairing. However, thermal circular dichroism melting profiles exhibit the presence of free energy of interaction between RNA and capsid protein. It is apparent that the capsid stabilizes the RNA structure with and without the addition of Mg2+. A close RNA capsid association is also derived from pH titration circular dichroism studies. The pH melting of the RNA in situ starts to occur about 0-5 pH unit higher with and without the addition of Mg2+ than the acid denaturation of isolated RNA. A direct correlation between bathochromic CD peak shift to the main position band and loss of survivors is noted for the thermal melting as well as pH titration experiments. It is suggested that the heat and pH induced conformational alterations of R17 RNA in situ coinciding with loss of infectivity occur after an in situ alteration of nucleic acid-capsid protein interaction.