RNase Y is responsible for uncoupling the expression of translation factor IF3 from that of the ribosomal proteins L35 and L20 in Bacillus subtilis

• Published in: Molecular microbiology Vol. 81; no. 6; pp. 1526 - 1541
• Main Authors: Bruscella, Patrice, Shahbabian, Karen, Laalami, Soumaya, Putzer, Harald
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.09.2011; Blackwell
• Subjects: Bacillus subtilis; Bacillus subtilis - enzymology; Bacillus subtilis - genetics; Bacillus subtilis - physiology; Bacterial proteins; Bacteriology; Base Sequence; Biological and medical sciences; Biosynthesis; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Profiling; Gene Expression Regulation, Bacterial; Genetics; Gram-positive bacteria; Metabolism; Microbiology; Models, Biological; Molecular Sequence Data; Prokaryotic Initiation Factor-3 - biosynthesis; Protein Biosynthesis; Ribonucleases - metabolism; Ribosomal Proteins - biosynthesis; RNA Stability; Bacillales; Initiation factor IF3; Bacillus subtilis; Bacteria; Bacillaceae; Ribosomal protein; Genetic translation
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1111/j.1365-2958.2011.07793.x

Summary RNase Y is a novel endoribonuclease affecting global mRNA metabolism. We show that this nuclease affects the expression of the Bacillus subtilis infC‐rpmI‐rplT operon, encoding translation initiation factor IF3 and the ribosomal proteins L35 and L20. This operon is autoregulated by a complex L20‐dependent transcription attenuation mechanism. L20 binds to a phylogenetically conserved domain on the 5′ untranslated region of the infC mRNA which mimics the L20 binding sites on 23S rRNA. We have identified a second promoter (P1) upstream of the previously identified promoter (P2). The P1, but not the P2, readthrough transcript is stabilized in a strain depleted for RNase Y. However, under these conditions infC biosynthesis is repressed threefold. We show that the unprocessed P1 transcript is non‐functional for IF3 translation but fully competent to express the co‐transcribed ribosomal protein genes. RNase Y cleavage of the P1 transcript creates an entry site for the 5′–3′ exonucleolytic activity of RNase J1 which degrades the infC mRNA when translation initiation efficiency is low. A second RNase Y cleavage is crucial for initiating degradation of the prematurely terminated infC leader RNAs, including the L20 operator complex, which permits efficient recycling of the L20 protein.