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Biophysical studies on circle formation by Sindbis virus 49 S RNA

Frey, Teryl K. and Gard, David L. and Strauss, James H. (1979) Biophysical studies on circle formation by Sindbis virus 49 S RNA. Journal of Molecular Biology, 132 (1). pp. 1-18. ISSN 0022-2836. doi:10.1016/0022-2836(79)90493-5.

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Sindbis virus 49 S RNA extracted from virions is completely in the form of hydrogen-bonded circles, which are separable from linear 49 S RNA in sucrose gradients containing 0·01 M-NaCl. The melting temperature (t_m) of the circles is 39·5°C in 0·02:3 M-NaCl and 53·5°C in O· l M-NaCl. The ΔH value for cyclization is - 160 kcal/mol and the ΔS approximately -500 entropy units. These parameters indicate that the length of the double-stranded region which is formed upon cyclization of the molecule is most likely short, in the order of 10 to 20 nucleotides. Our data indicate that extensive mismatching in this double-stranded region is unlikely. Intact linear 49 S RNA molecules readily renature to form circles under appropriate conditions, the energy of activation for this process being 42·6 kcal/mol. From the measured rate constants for cyclization, it is clear that Sindbis RNA will form circles readily under physiological conditions of temperature and ionic strength. The virion RNA from Semliki Forest virus also forms circles whose t_m value is very similar to that of Sindbis RNA circles, suggesting that the sequences involved in cyclization have been conserved.

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Additional Information:© 1979 Academic Press Inc. (London) Ltd. Received 20 March 1978, and in revised form 9 January 1979. The authors thank Edith M. Lenches and Mary A. Stammreich-Martin for their expert technical assistance in preparing cultures of chicken embryo fibroblasts and purifying some of the virus RNA used in these experiments. We are indebted to Dr. Welcome Bender and Pat Koen for showing us electron microscopic techniques, to Dr. Bruce Wallace for running slab gels for us, and to Dr. Daniel Kolakofsky for releasing information prior to publication. We thank Dr. Ellen G. Strauss for her helpful discussions and critical reading of this manuscript. One of us (T. K. F.) thanks his wife, Phyllis, for filling many of the innumerable scintillation vials utilized in this project. This study 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. One author (T. K. F.) has been supported by a Predoctoral Fellowship from the National Science Foundation and by training grant no. 5-T1-GM86 from the National Institutes of Health.
Funding AgencyGrant Number
NSFPCM 77-26728
NIHGM 06965
NIHAI 10793
NSF Predoctoral FellowshipUNSPECIFIED
NIH Predoctoral Fellowship5-T1-GM86
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Record Number:CaltechAUTHORS:20160523-153204155
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Official Citation:Teryl K. Frey, David L. Gard, James H. Strauss, Biophysical studies on circle formation by Sindbis virus 49 S RNA, Journal of Molecular Biology, Volume 132, Issue 1, 1979, Pages 1-18, ISSN 0022-2836, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:67268
Deposited By: Donna Wrublewski
Deposited On:23 May 2016 23:58
Last Modified:11 Nov 2021 00:29

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