The Functional Differences between the GroEL Chaperonin of Escherichia coli and the HtpB Chaperonin of Legionella pneumophila Can Be Mapped to Specific Amino Acid Residues.

Karla N Valenzuela-Valderas,Rafael A Garduño,John R Rohde,Gabriel Moreno-Hagelsieb

doi:10.3390/biom12010059

Karla N Valenzuela-Valderas, Rafael A Garduño + Show 2 more

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https://doi.org/10.3390/biom12010059

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Journal: Biomolecules	Publication Date: Dec 31, 2021
Citations: 3	License type: CC BY 4.0

Affiliation: Dalhousie University, Wilfrid Laurier University

Abstract

Group I chaperonins are a highly conserved family of essential proteins that self-assemble into molecular nanoboxes that mediate the folding of cytoplasmic proteins in bacteria and organelles. GroEL, the chaperonin of Escherichia coli, is the archetype of the family. Protein folding-independent functions have been described for numerous chaperonins, including HtpB, the chaperonin of the bacterial pathogen Legionella pneumophila. Several protein folding-independent functions attributed to HtpB are not shared by GroEL, suggesting that differences in the amino acid (aa) sequence between these two proteins could correlate with functional differences. GroEL and HtpB differ in 137 scattered aa positions. Using the Evolutionary Trace (ET) bioinformatics method, site-directed mutagenesis, and a functional reporter test based upon a yeast-two-hybrid interaction with the eukaryotic protein ECM29, it was determined that out of those 137 aa, ten (M68, M212, S236, K298, N507 and the cluster AEHKD in positions 471-475) were involved in the interaction of HtpB with ECM29. GroEL was completely unable to interact with ECM29, but when GroEL was modified at those 10 aa positions, to display the HtpB aa, it acquired a weak ability to interact with ECM29. This constitutes proof of concept that the unique functional abilities of HtpB can be mapped to specific aa positions.

Highlights

Accepted: 28 December 2021Group I chaperonins constitute a large family of highly conserved ~60-kDa essential proteins that typically reside in the bacterial cytoplasm, or the organellar matrix
Escherichia coli is the best characterized group I chaperonin/co-chaperonin complex. In spite of their sequence and structural conservation, imposed by their essential protein folding function, bacterial 60-kDa chaperonins show a diversity of protein foldingindependent functions, as reviewed by Henderson and Martin [5]. It is not known whether chaperonins from free-living bacteria can display protein folding-independent functions, so far such functions have only been described in chaperonins of bacterial
E. coli strains DH5α and JM109, described by Sambrook et al [34] were grown at 37 ◦ C in Lysogeny broth (LB) or on LB plates solidified with 2% agar

Summary

Introduction

Group I chaperonins constitute a large family of highly conserved ~60-kDa essential proteins that typically reside in the bacterial cytoplasm, or the organellar matrix. They team-up with the conserved ~10-kDa essential co-chaperonins, to self-assemble into molecular nanoboxes that mediate the folding of cytoplasmic proteins, and have recently found some biotechnological applications, as reviewed by Horwich and Fenton, and Pipaón et al [1,2]. Escherichia coli is the best characterized group I chaperonin/co-chaperonin complex In spite of their sequence and structural conservation, imposed by their essential protein folding function, bacterial 60-kDa chaperonins show a diversity of protein foldingindependent functions, as reviewed by Henderson and Martin [5]. It is not known whether chaperonins from free-living bacteria can display protein folding-independent functions, so far such functions have only been described in chaperonins of bacterial

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