DEMONSTRATION OF SEQUENCE DIFFERENCES IN RIBONUCLEIC ACIDS OF BACTERIOPHAGE MS2 AND A MUTANT OF MS2

Procedures for the detection of small differences in ribonucleic acids of large molecular weight have been developed. The analyses of the oligonucleotides produced by specific enzymic degradation ofthe ribonucleic acids of the bacteriophage MS2 and a nitrous acid mutant of MS2 have been used to demonstrate sequence differences in these macromolecules. The oligonucleotides were fractionated initially according to size on a DEAE-Sephadex column at neutral pH in the presence of 7 m urea. Subsequently, each group of larger oligonucleotides was subfractionated according to the base content of its components, using a new application of DEAE-Sephadex columns: the ion-exchange chromatography of oligonucleotides at low pH in the absence of urea. Elution patterns obtained for the components of the two ribonucleic acids showed a small number of differences, the most notable of which occurred in the chromatographic group corresponding to the tridecanucleotides. In the case of the wild-type nucleic acid, this group, on subfractionation, produced four oligonucleotide peaks, while in the subfractionation of the corresponding group from the mutant, two of these peaks were shown to be absent. The most reasonable explanation for these two differences observed in the digest ofthe mutant ribonucleic acid is that they have resulted from sequence changes in the mutant nucleic acid caused by the replacement of two adenine bases in the wild-type nucleic acid by two guanine bases. © 1969, American Chemical Society. All rights reserved.