The flax genome reveals orbitide diversity

Area of Science:

• Plant biochemistry
• Genomics
• Bioinformatics

Background:

• Ribosomally-synthesized cyclic peptides in plants possess valuable bioactivities.
• Genome sequencing aids in identifying cyclic peptide precursors.
• Limited research exists on chemically unidentified cyclic peptides.

Purpose of the Study:

• To investigate the genetic diversity of linusorbs, a type of cyclic peptide in flax (Linum usitatissimum).
• To develop and apply novel bioinformatic strategies for identifying previously undiscovered cyclic peptide precursors.

Main Methods:

• Phylogenetic analysis of known linusorb precursor proteins.
• Profile-based mining using Hidden Markov Models (HMMs) and customized profiles for genome-wide searches.
• Genome reannotation and comparative analysis of identified repeats.

Main Results:

• Phylogenetic analysis revealed distinct clades for known linusorb precursors.
• HMM-based approach identified 58 novel linusorb-embedded repeats in 8 proteins.
• Customized profile search identified 281 linusorb-like domains (LLDRs) in 25 proteins, suggesting convergent evolution.

Conclusions:

• Profile-based mining is effective for analyzing repetitive sequences.
• The 25 identified LLDR proteins represent significant potential cyclic peptide diversity in flax.
• This study provides a foundation for future research on the function and evolution of flax cyclic peptides.