Diversity-generating retroelements: natural variation, classification and evolution inferred from a large-scale...

Area of Science:

• Genetics and Molecular Biology
• Bioinformatics
• Evolutionary Biology

Background:

• Diversity-generating retroelements (DGRs) are mobile genetic elements utilizing reverse transcription to generate sequence diversity.
• Understanding the natural distribution and diversity of DGRs is crucial for deciphering their biological functions and evolutionary history.

Purpose of the Study:

• To conduct a comprehensive bioinformatic analysis of the DGR sequence landscape in public databases.
• To establish a curated reference set of putatively functional DGRs and classify their key components.
• To identify novel DGR-associated genes and explore DGR diversity across different microbial lineages.

Main Methods:

• Comparative bioinformatic analysis of DGR sequences retrieved from GenBank.
• Identification and classification of DGRs, target genes, variable repeats, and DGR cassette architectures.
• Analysis of DGR distribution, horizontal transfer events, and sequence diversity in various archaeal and bacterial phyla.

Main Results:

• Over 350 unique DGRs were identified, forming a reference set for functional DGRs.
• Classification revealed significant variability in target genes, suggesting roles in numerous biological processes.
• Evidence for horizontal transfer was found, with some DGR lineages showing specialized properties; high diversity was noted in specific archaeal and bacterial groups.

Conclusions:

• This study provides a foundational classification framework for DGRs, essential for future discoveries.
• The extensive variability and distribution of DGRs highlight their significant, yet largely unexplored, impact on microbial evolution and function.
• Further research is needed to elucidate the functions of DGRs, particularly in underrepresented microbial taxa.