The activity of the DNA packaging adenosine triphosphatase (ATPase) of the Bacillus subtilis bacteriophage φ29 is dependent upon prohead RNA. The 174 nucleotide viralencoded RNA is positioned on the head-tail connector at the portal vertex of the φ29 precursor shell (prohead). Here, the RNA interacts with the ATP-binding gene 16 product (gp16) to constitute the DNA-packaging ATPase and initiate DNA packaging in vitro. Both the prohead connector (gene 10 product, gp10) and gp16 may utilize an RNA recognition motif characteristic of a number of RNA-associated proteins, and the binding of gp16 by proheads shields the prohead RNA from RNase A. The ATPase activity of gp16 is stimulated fourfold by RNA and tenfold by proheads with RNA. RNA is needed continuously for the gp16/RNA ATPase activity and is essential for the gp16/prohead ATPase activity. The prohead, with its connector, RNA and associated gp16 in an assembly-regulated configuration, hydrolyzes ATP and drives φ29 DNA translation.
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We. acknowledge the technical help of Charlene Peterson and Sarah Turnquist. B. subtilis (pUM102) was constructed by Jesdawan Wiehitwechkarn. Sarah Turnquist provided Fig. 1 (lanes 1 and 2) and Fig. 2. Stephen Eriekson provided Fig. 1 (lanes 3 and 4). Suzanne Bailey identified 2 RRMs in gpl0. We thank Charlene Peterson for preparing the manuscript. This work was supported by grants DE-03606, DE-08515 and GM-39931 from the National Institutes of Health. S.G. is a graduate student in Genetics and Cell Biology at the University of Minnesota.