Stem-loop structures control mRNA processing of the cellulosomal cip-cel operon in Ruminiclostridium cellulolyticum

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• Ruminiclostridium cellulolyticum produces cellulosomes, essential extracellular enzyme complexes for cellulose degradation.
• Cellulosome component genes are organized in the cip-cel operon, with expression regulated by post-transcriptional RNA processing and stabilization.

Purpose of the Study:

• To investigate the role of RNA processing events in controlling gene expression and subunit stoichiometry within the cip-cel operon.
• To elucidate the structural requirements of RNA elements involved in transcript processing.

Main Methods:

• Analysis of RNA processing events at intergenic regions (IRs) within the cip-cel operon.
• Identification and characterization of stem-loop structures involved in RNA cleavage.
• Determination of cleavage site locations relative to stem-loop structures.

Main Results:

• Six intergenic regions (IRs) with stem-loop structures were identified in the cip-cel operon, acting as RNA cleavage signals.
• Stem-loop structures stabilize processed transcripts and are recognized by endoribonucleases.
• Cleavage sites were typically downstream of stem-loops, with GC-rich stems being crucial, except for IR4 where cleavage occurred upstream, influenced by AT-pair regions.

Conclusions:

• Stem-loop structures in the cip-cel operon function as RNA cleavage signals, dictating cleavage site location and transcript stoichiometry.
• This post-transcriptional regulation mechanism controls cellulosome production.
• These findings offer potential for designing synthetic elements to manipulate gene expression.