Evolution of light-harvesting complex proteins from Chl c-containing algae

Area of Science:

• Photosynthesis research
• Algal molecular biology
• Evolutionary genomics

Background:

• Light harvesting complex (LHC) proteins are crucial for photosynthesis, binding chlorophyll (Chl) and carotenoids to transfer light energy.
• Research has primarily focused on plant and chlorophyte LHCs binding Chl a/b, with less attention on Chl a/c-binding LHCs in other algae.
• Previous studies suggested lineage-specific LHC subfamilies, but genome data indicated gene duplication and potential endosymbiotic influence.

Purpose of the Study:

• To reconstruct a comprehensive phylogeny of LHC proteins in Chl c-containing algae and related lineages.
• To investigate the diversity and evolutionary patterns of LHC gene families in algae.
• To provide a phylogenetic context for understanding LHC functional differentiation and evolution.

Main Methods:

• Phylogenetic analysis of LHC proteins.
• Utilized large-scale genome data from recent sequencing projects.
• Expanded taxon sampling approximately tenfold compared to previous studies.

Main Results:

• The reconstructed phylogeny reveals that individual algal taxa possess LHC proteins from multiple subfamilies.
• Several LHC subfamilies are present in distantly related algal lineages, challenging previous assumptions of lineage specificity.
• Phylogenetic patterns support functional differentiation within LHC gene families, consistent with expression, binding, and association data.

Conclusions:

• Algal LHC diversity is greater than previously understood, with multiple subfamilies per lineage.
• Evolutionary relationships support the hypothesized origin of Chl c plastids.
• This study provides a broader phylogenetic framework for interpreting experimental findings on LHC molecular function.