Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published September 1978 | public
Journal Article

Replication of Sindbis Virus VII. Location of 5-Methyl Cytidine Residues in Virus-Specific RNA

Abstract

Sindbis virus intracellular 26 S and 49 S RNA contain internal 5-methyl cytidine (m^(5)C) residues. In [methyl-^(3)H]methionine-labeled Sindbis virus RNA, an average of 19% of the methyl-^(3)H label in 26 S RNA is in m^(5)C, whereas in intracellular 49 S RNA, an average of 8% of the methyl-^(3)H label is in m^(5)C, the remainder of the label being in the cap. Sindbis virion 49 S RNA contains much less m^(5)C than intracellular 49 S RNA extracted from the same cells. In 26 S RNA, m^(5)C residues occur in five oligonucleotides, four of which have been identified as having base compositions of C_(4)A_(4)UG, C_(6)A_(2)UG, C_(3)A_(2)G, and C_(2)AG, which are found distributed between two major locations, one approximately 4000 nucleotides from the 3′ end and the other about 1200 nucleotides from the 3′ end (out of a total length of 5000 nucleotides). The m^(5)C containing nucleotide C_(2)AG is found only at the former location and the oligonucleotide of composition C_(4)A_(4)UG (which contains 40–50%. of the total m^(5)C in 26 S RNA) is restricted to the latter location; the distribution of methyl label between the two locations suggests that each region contains at least two of the methylated sequences. Although there appear to be five specific sites for methylation on the 26 S RNA, only a minority of these sites are modified, as each 26 S RNA molecule contains an average of less than one m^(5)C. Sindbis virus 26 S RNA isolated from both polysomes and nonpolysomal ribonucleoproteins contain equal amounts of m^(5)C. 49 S RNA isolated from polysomes contains 60–80% more m^(5)C than does 49 S RNA which is isolated primarily from nucleocapsids. The m^(5)C residues thus may be somehow involved in translating the viral RNA.

Additional Information

© 1978 Academic Press, Inc. Accepted June 5, 1978. We thank Edith M. Lenches, Agnes V. Raviol, and Mary A. Stammreich-Martin for their excellent technical assistance in preparing cell cultures. We are indebted to Dr. Lloyd H. Smith for teaching us fingerprinting procedures and Charles M. Rice, III for helping us prepare polysomes. We thank Dr. Ellen G. Strauss for her critical reading of this manuscript. TKF thanks his wife, Phyllis, for slicing many electropherograms. This research was supported by Grant PCM 77-26728 from the National Science Foundation and by Grants GM 06965 and AI 10793 from the National Institutes of Health. TKF was supported by a Predoctoral Fellowship from the National Science Foundation and by Training Grant No. 5-T1-GM86-2 from the National Institutes of Health.

Additional details

Created:
August 19, 2023
Modified:
October 18, 2023