Ms1 RNA increases the amount of RNA polymerase in Mycobacterium smegmatis

Summary Ms1 is a sRNA recently found in mycobacteria and several other actinobacterial species. Ms1 interacts with the RNA polymerase (RNAP) core devoid of sigma factors, which differs from 6S RNA that binds to RNAP holoenzymes containing the primary sigma factor. Here we show that Ms1 is the most a...

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Published in:Molecular microbiology 2019-02, Vol.111 (2), p.354-372
Main Authors: Šiková, Michaela, Janoušková, Martina, Ramaniuk, Olga, Páleníková, Petra, Pospíšil, Jiří, Bartl, Pavel, Suder, Agnieszka, Pajer, Petr, Kubičková, Pavla, Pavliš, Ota, Hradilová, Miluše, Vítovská, Dragana, Šanderová, Hana, Převorovský, Martin, Hnilicová, Jarmila, Krásný, Libor
Format: Article
Language:English
Subjects:
Accumulation
Biodegradation
DNA-directed RNA polymerase
Environmental changes
Mycobacterium smegmatis
Polynucleotide phosphorylase
Proteins
Ribonuclease
Ribonucleic acid
RNA
RNA polymerase
rRNA
Sigma factor
Stationary phase
Transcription
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Summary:Summary Ms1 is a sRNA recently found in mycobacteria and several other actinobacterial species. Ms1 interacts with the RNA polymerase (RNAP) core devoid of sigma factors, which differs from 6S RNA that binds to RNAP holoenzymes containing the primary sigma factor. Here we show that Ms1 is the most abundant non‐rRNA transcript in stationary phase in Mycobacterium smegmatis. The accumulation of Ms1 stems from its high‐level synthesis combined with decreased degradation. We identify the Ms1 promoter, PMs1, and cis‐acting elements important for its activity. Furthermore, we demonstrate that PNPase (an RNase) contributes to the differential accumulation of Ms1 during growth. Then, by comparing the transcriptomes of wt and ΔMs1 strains from stationary phase, we reveal that Ms1 affects the intracellular level of RNAP. The absence of Ms1 results in decreased levels of the mRNAs encoding β and β′ subunits of RNAP, which is also reflected at the protein level. Thus, the ΔMs1 strain has a smaller pool of RNAPs available when the transcriptional demand increases. This contributes to the inability of the ΔMs1 strain to rapidly react to environmental changes during outgrowth from stationary phase. Ms1 RNA binds the RNA polymerase (RNAP) core and is the most abundant non‐rRNA transcript in stationary phase in Mycobacterium smegmatis. This study identifies the mechanisms responsible for its high accumulation. Further, we show that Ms1 increases expression of two RNAP subunits, β and β′. The increased level of RNAP helps mycobacterial cells rapidly start transcription of appropriate genes when surrounding conditions become favorable.
ISSN:0950-382X
1365-2958
DOI:10.1111/mmi.14159