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<p><i>E. coli</i> chaperonin GroEL forms nano-cages for protein folding. Although the chaperonin-mediated protein folding mechanism is well understood, the role of the conserved glycine and methionine-rich carboxy-terminal residues remains unclear. Bacteria with multiple chaperonins always retain at least one paralogue having the gly-met-rich C-terminus, indicating an essential conserved function. Here, we observed a stronger selection pressure on the paralogues with gly-met-rich C-termini, consistent with their ancestral functional importance. <i>E. coli</i> GroEL variants having mutations in their C-termini failed to functionally replace GroEL, suggesting the functional significance of the gly-met-rich C-termini. Further, our structural modelling and normal mode analysis showed that the C-terminal region shuttles between two cavity-specific conformations that correlate with the client-protein-binding apical domains, supporting C-termini’s role in client protein encapsulation. Therefore, employing phylogenetic, genetic, and structural tools, we demonstrate that the gly-met-rich C-termini are functionally significant in chaperonin-mediated protein folding function. Owing to the pathogenic roles of the chaperonins having non-canonical C-termini, future investigations on the client protein selectivity will enable understanding the disease-specific client protein folding pathways and treatment options.</p><p></p>

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Genetic and structural insights into the functional importance of the conserved gly-met-rich C-terminal tails in bacterial chaperonins

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年4月8日

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  • C. M. Santosh Kumar,
  • Aisha M. Mai,
  • Shekhar C. Mande,
  • Peter A. Lund

摘要

E. coli chaperonin GroEL forms nano-cages for protein folding. Although the chaperonin-mediated protein folding mechanism is well understood, the role of the conserved glycine and methionine-rich carboxy-terminal residues remains unclear. Bacteria with multiple chaperonins always retain at least one paralogue having the gly-met-rich C-terminus, indicating an essential conserved function. Here, we observed a stronger selection pressure on the paralogues with gly-met-rich C-termini, consistent with their ancestral functional importance. E. coli GroEL variants having mutations in their C-termini failed to functionally replace GroEL, suggesting the functional significance of the gly-met-rich C-termini. Further, our structural modelling and normal mode analysis showed that the C-terminal region shuttles between two cavity-specific conformations that correlate with the client-protein-binding apical domains, supporting C-termini’s role in client protein encapsulation. Therefore, employing phylogenetic, genetic, and structural tools, we demonstrate that the gly-met-rich C-termini are functionally significant in chaperonin-mediated protein folding function. Owing to the pathogenic roles of the chaperonins having non-canonical C-termini, future investigations on the client protein selectivity will enable understanding the disease-specific client protein folding pathways and treatment options.