Peptide Hormone Biogenesis

Peptides serve important functions as peptide hormones and growth factors for the regulation of plant development. Peptides also serve as signal molecules for the activation of plant defense responses agianst pests and pathogens. Such peptides are generally synthesized as larger and inactive precursor proteins. Proteolytic processing of the precursor is required to produce the bioactive peptide. The proteases responsible for pepetide maturation are thus indispensable for peptide hormone signaling. We aim to identify these proteases and to understand their function as regulatory factors during peptide hormone biogenesis.

We could show that the enzymes responsible for peptide hormone maturation belong to the family of subtilisin-like proteases (subtilases). 56 subtilases are encoded in the Arabidopsis gemnome, and 86 subtilase genes are found in the tomato genome. Subtilases are also synthesized as inactive pre-pro-proteins. For activation, the inhibitory prodomain is cleaved off within the secretory pathway. We investigate the physiological role of individual subtilases  by gain- (overexpression) and loss-of-function analysis (T-DNA insertion and CRISP/Cas9 mutagenesis). Reprter genes are used to analyze the cell type and tissue-specific expresssion of subtilases in transgenic plants.