Biology subjects

Baniulyte, G.

Publications and source records attributed to Baniulyte, G..

2 recordsLinked to original sources

bioRxiv2018

Nus Factors Prevent Premature Transcription Termination of Bacterial CRISPR Arrays

A hallmark of CRISPR-Cas immunity systems is the CRISPR array, a genomic locus consisting of short, repeated sequences ("repeats") interspersed with short, variable sequences ("spacers"). CRISPR arrays are transcribed and processed into individual CRISPR RNAs (crRNAs) that each include a single spacer, and direct Cas proteins to complementary sequence in invading nucleic acid. Most bacterial CRISPR array transcripts are unusually long for untranslated RNA, suggesting the existence of mechanisms to prevent premature transcription termination by Rho, a conserved bacterial transcription termination factor that rapidly terminates untranslated RNA. We show that Rho termination functionally limits the length of bacterial CRISPR arrays, and we identify a widespread antitermination mechanism that antagonizes Rho to facilitate complete transcription of CRISPR arrays. Thus, our data highlight the importance of Rho termination in the evolution of bacterial CRISPR-Cas systems.

microbiology↗

bioRxiv2016

Nus factors have a widespread regulatory function in bacteria

Nus factors are broadly conserved across bacterial species, and are often essential for viability. A complex of five Nus factors (NusB, NusE, NusA, NusG and SuhB) is considered to be a dedicated regulator of ribosomal RNA folding, and has been shown to prevent Rho-dependent transcription termination. We have established the first cellular function for the Nus factor complex beyond regulation of ribosomal assembly: repression of the Nus factor-encoding gene, suhB. This repression occurs by translation inhibition followed by Rho-dependent transcription termination. Thus, the Nus factor complex can prevent or promote Rho activity depending on the gene context. Extensive conservation of NusB/E binding sites upstream of nus factor genes suggests that Nus factor autoregulation occurs in many species. Putative NusB/E binding sites are also found upstream of many other genes in diverse species, and we demonstrate Nus factor regulation of one such gene in Citrobacter koseri. We conclude that Nus factors have an evolutionarily widespread regulatory function beyond ribosomal RNA, and that they are often autoregulatory.

microbiology↗