Control of gene expression in bacteriophage P22 by a small antisense RNA. II. Characterization of mutants defective in repression

T H Wu, S M Liao, W R McClure, M M Susskind
1987 Genes & Development  
Phage P22 produces antirepressor protein early after infection from a transcript initiated at the P.., promoter. After the first few minutes of infection, transcription from Pant is repressed by a protein encoded by the arc gene. Antirepressor is not produced late in infection, even though the antirepressor gene, ant, is transcribed from the late operon promoter Plate. We describe the isolation of P22 mutants that synthesize antirepressor from the Plate transcript. The mutations inactivate a
more » ... ons inactivate a promoter 1"8." which lies within the ant coding sequence and directs the synthesis of sar RNA, a small antisense regulatory RNA complementary to the ant ribosome binding site. Characterization of the Psa, down-mutants shows that transcription from P,~ interferes with synthesis of antirepressor from both the Plate and Pant transcripts. Since sar RNA represses synthesis of antirepressor/n trans, we propose that sar RNA base-pairs with ant mRNA to inhibit antirepressor synthesis at a post-transcriptional level. The role and importance of sar RNA in P22 biology are discussed. [Key Words: Antisense RNA~ antirepressor protein~ repression-defective mutants~ RNA-RNA pairing]
doi:10.1101/gad.1.2.204 pmid:2445627 fatcat:u46md5pphbg57ffsc4i5qc25nm