A human RNase E-like activity that cleaves RNA sequences involved in mRNA stability control

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Messenger RNA (mRNA) degradation is crucial for gene regulation.
• RNase E is a key enzyme in bacterial mRNA processing and decay.
• The existence of a similar enzyme in humans was previously unknown.

Purpose of the Study:

• To identify and characterize an endoribonucleolytic activity in human cells analogous to E. coli RNase E.
• To investigate the role of this human enzyme in mRNA decay, particularly AU-rich elements.
• To explore the evolutionary conservation of mRNA degradation pathways.

Main Methods:

• Detection of endoribonucleolytic activity in human cell extracts.
• Partial purification of the human enzyme using ion-exchange chromatography.
• Antibody-based detection of the purified human protein.
• RNA cleavage assays using bacterial and human mRNA fragments, including AUUUA motifs.

Main Results:

• A human endoribonucleolytic activity was identified, processing E. coli 9S RNA and ompA mRNA with RNase E-like specificity.
• The active human fractions contained a protein recognized by antibodies against E. coli RNase E.
• Both E. coli RNase E and its human counterpart cleaved RNA containing AUUUA motifs, including human c-myc mRNA, suggesting a role in mammalian mRNA decay.
• RNA with multiple AUUUA motifs was cleaved more efficiently.

Conclusions:

• A eukaryotic endoribonucleolytic activity homologous to bacterial RNase E has been discovered in human cells.
• This finding indicates evolutionary conservation of mRNA degradation machinery components.
• The identified human enzyme may play a significant role in regulating mammalian mRNA stability and decay.