XVI International Botanical Congess
Chloroplast biogenesis and its various functions depend on numerous nuclear-encoded proteins that are synthesized in the cytosol with a transit peptide which directs import into the chloroplast. We identified one stromal processing protease (SPP) that removes transit peptides of proteins destined for different pathways and compartments. The mature protein and the intact transit peptide are generated simultaneously during processing. However, whereas the mature protein is released and remains stable, SPP converts the transit peptide into a subfragment. Significantly, specific degradation of the subfragment is carried out by a newly identified soluble protease activity that is ATP- and metal-dependent.