The complex evolutionary dynamics of Hsp70s: a genomic and functional perspective

Area of Science:

• Molecular Biology
• Evolutionary Biology
• Fungal Genomics

Background:

• Heat shock protein 70 (Hsp70) molecular chaperones are vital for maintaining cellular proteostasis by preventing protein aggregation and promoting proper folding.
• While Hsp70 function is well-studied, their evolutionary dynamics across different species remain largely unexplored.

Purpose of the Study:

• To investigate the evolutionary trajectories of Hsp70 chaperones within the fungal Ascomycota clade.
• To identify and characterize Hsp70 orthologs across diverse fungal genomes and analyze their evolutionary patterns.

Main Methods:

• Comparative genomics approach using Saccharomyces cerevisiae Hsp70s as a reference.
• Identification of 491 Hsp70 orthologs from 53 Ascomycota genomes.
• Phylogenetic analysis to determine evolutionary modes (concerted evolution, birth-death, divergent evolution).

Main Results:

• Seven Hsp70 subfamilies (SSA, SSB, KAR, SSC, SSE, SSZ, LHS) were identified, with each surveyed genome containing at least one member of each.
• Subfamilies exhibited varied evolutionary patterns: SSB under concerted evolution, SSA and SSC under birth-death dynamics, and KAR, SSE, SSZ, LHS under simple divergent evolution.
• The study highlights the presence of seven core Hsp70s as functional and evolutionary units across Ascomycota.

Conclusions:

• Hsp70 proteins, despite their conserved function, display surprisingly complex and dynamic evolutionary histories.
• The distinct evolutionary modes across Hsp70 subfamilies reflect differential adaptation and diversification within fungal lineages.