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

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.

Complete genome sequence and potential pathogenic assessment of Flavobacterium plurextorumRSG‐18 isolated from the gut of Schlegel's black rockfish, Sebastes schlegelii

“…However, it showed less than 70% nucleotide identity, and the actual gene annotated by Prokka was groL , which encodes a chaperonin GroEL. According to Valenzuela‐Valderas et al, GroEL in Escherichia coli differs by several amino acids from HtpB in Legionella pneumophila (the reference species for htpB in the VFDB), leading to a functionally different protein folding that may not be conducive to infection (Valenzuela‐Valderas et al, 2022 ). Therefore, it is not expected to be virulent and has only been reported to be immunogenic in Flavobacterium (Liu et al, 2012 ; Valenzuela‐Valderas et al, 2022 ).…”

Pathogenicity and Genomic Characteristics Analysis of Pasteurella multocida Serotype A Isolated from Argali Hybrid Sheep

“…HtpB encodes a chaperone protein known to modify eukaryotic cell signaling pathways, facilitating the entry of bacteria into the mammalian cytoplasm. This capability enhances bacterial replication within host cells [ 32 ]. The identification of the htpB gene in the Legionellosis pathway strongly suggests that the P. multocida SHZ01 strain may employ this gene to communicate with host cells.…”

Legionella Research: Still Many Miles to Go

“…Valenzuela-Valderas et al [11] compared the primary structures of GroEL and HtpB and were successful in demonstrating that at least 10 amino acid residues were important for the interaction of HtpB with the eukaryotic proteasome-related protein ECM29. Using Evolutionary Trace Analysis, the authors identified and mutated amino acid residues potentially involved in the protein-folding-independent functions of HtpB.…”