Amino acids biosynthesis and nitrogen assimilation pathways: a great genomic deletion during eukaryotes evolution

Area of Science:

• Biochemistry
• Genomics
• Evolutionary Biology

Background:

• Amino acids are vital protein building blocks and metabolic intermediates.
• Essential Amino Acids (EAAs) cannot be synthesized by many organisms.
• Understanding gene loss in amino acid biosynthesis is crucial for evolutionary insights.

Purpose of the Study:

• Investigate the distribution of EAA biosynthesis and nitrogen assimilation.
• Explore the evolutionary history of amino acid auxotrophy across diverse taxa.
• Propose a model for the emergence of essential amino acids.

Main Methods:

• Comparative genomics using homologous gene clustering.
• Analysis of protein databases with complete and incomplete genomes.
• Examination of enzyme presence/absence at the phyla level.

Main Results:

• Widespread loss of EAA biosynthesis observed in eukaryotes.
• Multiple secondary gene losses contribute to auxotrophy.
• Derived metazoans exhibit subsequent nitrogen assimilation deficiencies.

Conclusions:

• The
• Great Deletion
• model explains EAA essentiality.
• This phenomenon is linked to relaxed selection pressures from heterotrophy.
• Organic nitrogen dependency arises in metazoans post-deletion.