Putative MutS2 Homologs in Algae: More Goods in Shopping Bag?

Area of Science:

• Molecular Biology
• Evolutionary Biology
• Genetics

Background:

• MutS2 proteins are implicated in DNA repair and translation control in bacteria.
• While MutS2 homologs exist in plants and some algae, their diversity across eukaryotes is largely uncharacterized.
• Understanding MutS2 evolution is crucial for deciphering genetic processes in diverse photosynthetic organisms.

Purpose of the Study:

• To investigate the diversity and evolutionary history of MutS2 homologs in photosynthetic eukaryotes.
• To characterize the domain composition and structural features of eukaryotic MutS2-like proteins.
• To infer evolutionary relationships of MutS2 homologs and their implications for algal endosymbiosis.

Main Methods:

• Bioinformatic analysis of amino acid sequences from various photosynthetic eukaryotes.
• Identification and classification of MutS2 homologs based on domain architecture (e.g., Smr domain, ATPase domain).
• Phylogenetic analysis using sequence data to reconstruct evolutionary relationships, including comparisons with bacterial homologs.

Main Results:

• Three distinct groups of MutS2 homologs were identified in photosynthetic eukaryotes based on domain composition.
• Phylogenetic analysis revealed two major eukaryotic clades, with distinct affiliations to Archaeplastida, haptophytes, and CASH groups (cryptophytes, alveolates, stramenopiles).
• Bacterial MutS2 and Deltaproteobacteria proteins showed specific clustering patterns with eukaryotic groups, suggesting complex evolutionary trajectories.

Conclusions:

• The study reveals significant diversity in eukaryotic MutS2 proteins, extending beyond previously known occurrences.
• Phylogenetic patterns do not support a simple dichotomy based on red or green algal plastid origins, suggesting mosaic evolution.
• The findings provide insights into the complex evolutionary history of genes involved in genetic maintenance across diverse algal lineages.