De novo birth and stepwise evolution of a seed peptide

Achala Sanjeevanie Jayasena Mederian Kotuwe

Research output: ThesisDoctoral Thesis

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Abstract

This thesis describes the stepwise evolution of a functional seed peptide called Sunflower Trypsin Inhibitor-1 (SFTI-1). SFTI-1 originates within the coding sequence of the seed albumin PawS1 and uses the same processing enzyme, asparanginyl endopeptidase for maturation (Mylne, et al., 2011). This enzyme has evolved to cleave a tail peptide from precursors and couple to a transpeptidation reaction to make macrocyclic peptides (Bernath-Levin, et al., 2015). Using de novo transcriptomics (Jayasena, et al., 2014) I traced the evolution of PawS1. The progenitor of PawS1 is a normal albumin which was interrupted by a genetic insertion ̴45 million years ago to create the ancestral PawS-Like (PawL1) genes (Elliott, et al., 2014) that encode Cys-less macrocycles. PawL1 further evolved to yield bicyclic peptides and acquire a biological function. The seed storage role of PawS1 in sunflower is little, explaining how PawS1 had the freedom to evolve buried peptides (Jayasena, et al., 2016).
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • The University of Western Australia
Award date13 Jul 2016
Publication statusUnpublished - 2015

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