A 5'-UTR cis-acting RNA element targeted by RNase III is essential for DNA simple sequence repeat-dependent phase variation in Haemophilus influenzae.

ABSTRACT: Simple sequence repeats (SSRs) are insertion-deletion mutational hotspots causing phase variation in bacterial genomes. When located in intergenic regions, SSR variation impacts transcription and may change post-transcriptional regulatory element targeting. Here, we show that transcription, 5'-UTR structure, and messenger RNA (mRNA) processing are key to bacterial SSR phase variation. Expression of the Haemophilus influenzae HMW1A adhesin is inversely proportional to the (5'-ATCTTTC)n SSR length upstream of the hmw1A gene. This repeat region is transcribed as part of the hmw 5'-UTR, which acts as a cis-acting regulatory element via a long hairpin structure involving 10 repeats on its left arm and a G-rich region on its right arm. The double strand-specific endoribonuclease RNase III proces

SUBMITTER: Rapun-Araiz B 

PROVIDER: S-EPMC12721329 | biostudies-literature | 2025 Nov

REPOSITORIES: biostudies-literature