Characterization of Escherichia coli chaperonin GroEL as a ribonuclease.

Chaperonins are evolutionarily conserved proteins that facilitate polypeptide assemblies. The most extensively studied chaperonin is GroEL, which plays a crucial role in Escherichia coli. In addition to its chaperone activity, the RNA cleavage activity of GroEL has also been proposed. However, direct evidence of GroEL as a ribonuclease (RNase) and its physiological significance has not been fully elucidated. Here, we characterized the role of GroEL in E. coli as an RNase distinct from RNase E/G activity using in vivo reporter assays, in vitro cleavage assays with varying reaction times, divalent ions, and 5' phosphorylation status. GroEL bound to single-stranded RNA at nanomolar concentrations. Functional analysis of GroEL chaperonin-defective mutants and segments identified specific regions, and the chaperone active status of GroEL is not a necessary factor for RNase activity. Additionally, RNase activity of GroEL was attenuated by co-overexpression with GroES. Finally, we characterized potential transcripts regulated by GroEL and the conserved RNase activity of GroEL in Shigella flexneri. Our findings indicate that GroEL is a novel post-transcriptional regulator in bacteria. Copyright © 2024 Elsevier B.V. All rights reserved.

Citation

Hyejin Cho, Kwang-Sun Kim. Characterization of Escherichia coli chaperonin GroEL as a ribonuclease. International journal of biological macromolecules. 2024 Oct 05;281(Pt 2):136330

PMID: 39370076

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