A cyclic hexamer of the 120-base prohead RNA (pRNA) is needed for efficient in vitro packaging of the B. subtilis bacteriophage θ29 genome. This capacity of pRNA to form higher multimers by intermolecular base pairing of identical subunits represents a new RNA structural motif. Dimers of pRNA are likely intermediates in formation of the cyclic hexamer. Athree-dimensional model of the pRNA hexamer is presented.
Bibliographical noteFunding Information:
This work was supported by National Institutes of Health research grants GM39931 and DE03606 to D. A. and by the Medical Research Council (MRC) of Canada. F. M. is a fellow of the MRC. We thank C. Peterson, S. Grimes, P. Jardine, and R. Chen for technical assistance and discussions.