Repetitive extragenic palindrome (REP) elements are local, context-dependent, dual 3'UTR regulators in Escherichia...

Area of Science:

• Molecular Biology
• Genomics
• Bacterial Genetics

Background:

• Repetitive extragenic palindromes (REPs) are abundant noncoding elements in the E. coli genome.
• The precise function of REPs remains largely undetermined, with proposed roles in chromosome organization, mRNA decay, and transcription termination.

Purpose of the Study:

• To elucidate the function of the model REP, REP325, within the yjdMN operon.
• To investigate the broader role of REPs in regulating gene expression across the E. coli genome.

Main Methods:

• Characterization of REP325 function in the yjdMN operon.
• Genome-wide RNA-sequencing (RNA-seq) analysis to assess REP associations with gene expression patterns.
• Analysis of REP sequence and structural features in relation to expression biases.

Main Results:

• REP325 acts as a 3'UTR-associated regulator, functioning as a Rho-dependent transcription terminator and an mRNA stabilizer.
• REPs with canonical structures are linked to upstream-biased expression in tandem gene pairs.
• REPs between convergent genes correlate with increased expression of both genes.
• REP function is context-dependent, influencing termination and mRNA stability variably.

Conclusions:

• REPs possess a dual regulatory role, controlling both transcriptional readthrough and mRNA decay.
• REP-mediated regulation contributes to gene expression diversity across E. coli strains.
• REPs offer a mechanism for modulating gene expression without altering coding sequences or promoters.