Disease relevance of pRNA

• A cyclic hexamer of the 120-base prohead RNA (pRNA) is needed for efficient in vitro packaging of the B. subtilis bacteriophage phi 29 genome [1].
• The small prohead RNA (pRNA) of the Bacillus subtilis bacteriophage phi 29 is essential for ATP-dependent packaging of viral DNA [2].
• Proheads produced in phage-infected cells carried 5.8 +/- 2.7 copies of pRNA, and proheads assembled in Escherichia coli in the absence of pRNA bound 6.0 +/- 3.5 copies of pRNA [2].
• Addition of 45% mutant pRNA resulted in a reduction of infectious virion production by 4 orders of magnitude, indicating that factors involved in viral assembly can be targets for efficient and specific antiviral treatment [3].

High impact information on pRNA

• This capacity of pRNA to form higher multimers by intermolecular base pairing of identical subunits represents a new RNA structural motif [1].
• Furthermore, when hybrid proheads carrying phi 29 pRNA are incubated with a mixture of DNAs from different sources, phi 29 DNA is selectively packaged, thus indicating that phi 29 pRNA determines the specificity of DNA packaging [4].
• The secondary and tertiary structures of the prohead binding site on pRNA have been probed using a series of specific mutant pRNAs and by measuring binding to RNA-free proheads and in vitro packaging of the DNA-gene product 3 (DNA.gp3) complex [5].
• The work described here constitutes an extremely sensitive assay system for the analysis of components in phi 29 assembly and dissection of functional domains of structural components, enzymes, and pRNA (C.-S. Lee and P. Guo, Virology 202:1039-1042, 1995) [6].
• The specific requirement of an adenine in phi 29 pRNA at this position, as well as conservation of this position in other phage pRNAs, implicates that this base may play a special role in either the DNA-packaging reaction or the maintenance of the pRNA tertiary structure [7].

Biological context of pRNA

• A small RNA (pRNA, 174 nt) is known to be essential for DNA packaging in bacteriophage phi 29 [4].
• Mutations of pRNA within the prohead binding site resulted in substantial loss of prohead binding capacity, while mutations outside of the footprint had moderate effects on prohead binding [8].
• Five oligos did not bind pRNA or inhibit the assembly of the virion, suggesting that the RNA sequences complementary to these oligos are nonessential or buried internally in the RNA [9].

Other interactions of pRNA

• In vitro mutagenesis was performed to identify the DNA packaging domain of the 120-base pRNA essential and specific for DNA encapsidation by bacteriophage phi 29 of Bacillus subtilis [10].

Analytical, diagnostic and therapeutic context of pRNA

• Fourteen mutant pRNA molecules were synthesized from DNA templates either directly after PCR or after cloning the PCR fragments into the pCR II vector [10].

References