Colocality to Cofunctionality: Eukaryotic Gene Neighborhoods as a Resource for Function Discovery.

Area of Science:

• Genomics
• Evolutionary Biology
• Bioinformatics

Background:

• Eukaryotic gene order is often considered random, unlike in bacteria.
• Identifying functionally related genes is crucial for understanding biological pathways.
• Traditional methods relying on sequence similarity are limited for nonmodel organisms like algae.

Purpose of the Study:

• To systematically identify functionally related gene neighborhoods in green algae.
• To leverage conserved gene proximity for functional annotation in understudied organisms.
• To uncover novel gene clusters and biosynthetic pathways in algae.

Main Methods:

• Comparative genomics to identify conserved proximal orthologous gene pairs across green algae classes.
• Reconstruction of evolutionary relationships to infer gene functions.
• Experimental validation using gene knockouts in Chlamydomonas reinhardtii.

Main Results:

• Identified 317 conserved gene neighborhoods, some predating the streptophyte-chlorophyte split (1,000 Ma).
• Discovered a novel mosaic pathway for mycosporine-like amino acids ('sunscreen').
• Uncovered two arsenic-detoxification neighborhoods, including novel algal genes, experimentally validated for arsenate resistance.

Conclusions:

• Conserved gene proximity is a powerful strategy for identifying functional gene clusters in eukaryotes, especially nonmodel organisms.
• This approach provides new insights into algal biochemistry, including UV protection and heavy metal detoxification.
• Updated gene annotations and evolutionary insights were provided for previously poorly characterized genes.