Domain combinations in archaeal, eubacterial and eukaryotic proteomes.

Area of Science:

• Evolutionary biology
• Genomics
• Structural biology
• Bioinformatics

Background:

• Proteins are constructed from a limited set of duplicated and combined domain families.
• Gene duplication, recombination, fusion, and fission are key processes generating new genes and protein diversity.
• Understanding these evolutionary mechanisms is crucial for deciphering genome complexity.

Purpose of the Study:

• To survey the evolutionary processes shaping protein domain combinations across 40 diverse genomes.
• To analyze the combinatorial behavior and phylogenetic distribution of protein domain superfamilies.
• To investigate the role of recombination in the evolution of kingdom-specific and species-specific functions.

Main Methods:

• Utilized domain and superfamily definitions from the Structural Classification of Proteins (SCOP) database.
• Analyzed pairwise adjacent domain combinations within 40 complete genome sequences.
• Surveyed the phylogenetic distribution of domain combinations and compared them with the RCSB Protein Data Bank.

Main Results:

• Identified 783 out of 859 SCOP superfamilies present in the analyzed genomes, forming 1307 pairwise combinations.
• Observed a scale-free network pattern in domain combinations, with most families combining with few others, while some are highly versatile.
• Found that kingdom-specific combinations are more likely to involve families common to all three kingdoms, suggesting recombination of ancestral families.

Conclusions:

• Recombination between common protein domain families, rather than the de novo invention of new families, is a major driver of evolutionary innovation.
• This process significantly contributes to the development of kingdom-specific and species-specific functions across all three biological kingdoms.
• The findings have implications for understanding genome evolution and guiding structural genomics efforts.