PRECURSOR OF C4 ANTISENSE RNA OF BACTERIOPHAGES P1 AND P7 IS A SUBSTRATE FOR RNASE-P OF ESCHERICHIA-COLI

The C4 repressor of the temperate bacteriophages P1 and P7 inhibits an tirepressor (Ant) synthesis and is essential for establishment and mai ntenance of lysogeny, C4 is an antisense RNA acting on a target, Ant m RNA, which is transcribed from the same promoter, The antisense-target RNA interaction requires processing of C4 RNA from a precursor RNA, H ere,ve show that 5' maturation of C4 RNA in vivo depends on RNase P. I n vitro, Escherichia coil RNase P and its catalytic RNA subunit (M1 RN A) can generate the mature 5' end of C4 RNA from P1 by a single endonu cleolytic cut, whereas RNase P from the E. coil rnpA49 mutant, carryin g a missense mutation in the RNase P protein subunit, is defective in the 5' maturation of C4 RNA, Primer extension analysis of RNA transcri bed in vivo from a plasmid carrying the P1 c4 gene revealed that 5'-ma ture C4 RNA was the predominant species in rnpA(+) bacteria, whereas v irtually no mature C4 RNA was found in the temperature-sensitive rnpA4 9 strain at the restrictive temperature, Instead, C4 RNA molecules car rying up to five extra nucleotides beyond the 5' end accumulated, The same phenotype was observed in rnpA(+) bacteria which harbored a plasm id carrying a P7 c4 mutant gene with a single C --> G base substitutio n in the structural homologue to the CCA 3' end of tRNAs, Implications of C4 RNA processing for the lysis/lysogeny decision process of bacte riophages P1 and P7 are discussed.