Abstract
Peptidomics is a challenging field to create a link between genomic information and biological function through biochemical analysis of expressed peptides, including precise identification of post-translational modifications and proteolytic processing. Small peptide hormones are usually encoded by multiple paralogous genes whose primary products are approximately 70- to 110-amino-acid cysteine-poor secreted peptides that exhibit sequence similarity within the C-terminal short conserved domain that correspond to the mature peptide sequences. By analogy with these examples, we speculated that if Arabidopsis contains genes for paralogous secreted peptides with similar features, they may encode small peptide signals generated by proteolytic processing. Using an in silico approach coupled with nano LC-MS/MS analysis of apoplastic peptides, we identified a novel 14-amino-acid peptide generated through post-translational modification and proteolytic processing. We will discuss possible functions of this peptide based on expression pattern analysis and gain-of-function phenotypes.
