Escherichia coli RNase E can efficiently replace RNase Y in Bacillus subtilis

Area of Science:

• Bacterial molecular biology
• Enzyme function and evolution
• RNA processing and degradation

Background:

• RNase Y and RNase E are essential endoribonucleases controlling mRNA turnover in Bacillus subtilis and Escherichia coli, respectively.
• These enzymes share similar in vitro cleavage specificity and subcellular localization, hinting at potential functional overlap.

Purpose of the Study:

• To investigate the functional equivalence of RNase E and RNase Y in vivo by assessing RNase E's ability to complement RNase Y-deficient B. subtilis.
• To identify key features of RNase E, such as localization and domain structure, critical for functional complementation.

Main Methods:

• Genetic complementation experiments introducing full-length and truncated RNase E into an RNase Y mutant of B. subtilis.
• Analysis of bacterial growth rates and genome-wide transcript profiling using high-throughput sequencing.
• In vitro cleavage assays comparing RNase Y, E, and J activities.

Main Results:

• Full-length RNase E significantly restored wild-type growth in the B. subtilis rny mutant.
• RNase E expression reversed transcript profiles at both individual gene and genome-wide levels.
• Inner membrane localization of RNase E was essential for efficient complementation, while C-terminal truncations had minor effects.

Conclusions:

• RNase E can functionally substitute for RNase Y in B. subtilis, demonstrating significant in vivo functional equivalence.
• Subcellular localization, specifically inner membrane targeting, is a critical determinant for the biological function of these essential bacterial ribonucleases.
• RNase Y and RNase E exemplify convergent evolution, developing similar low-specificity endonuclease activities vital for bacterial mRNA metabolism.