514 publications from this institution
Leader peptidase is an integral membrane protein of E. coli and it catalyses the removal of most signal peptides from translocated precursor proteins. In this study it is shown that when the transmembrane anchors are removed in vivo, the remaining catalytic domain can bind to inner and outer membranes of E. coli. Furthermore, the purified catalytic domain binds to inner membrane vesicles and vesicles composed of purified inner membrane lipids with comparable efficiency. It is shown that the interaction is caused by penetration of a part of the catalytic domain between the lipids. Penetration is mediated by phosphatidylethanolamine, the most abundant lipid in E. coli, and does not seem to depend on electrostatic interactions. A hydrophobic segment around the catalytically important residue serine 90 is required for the interaction with membranes.
Proteins in both prokaryotic and eukaryotic cells have to find their way among a plethora of subcellular compartments. The targeting information in most cases resides in distinct stretches of amino acids or targeting peptides (TPs). The sequence characteristics of a number of different TPs have been defined by comparative sequence analysis and experimental studies. TPs targeting proteins for secretion, for import into mitochondria, and for import into chloroplasts will be reviewed, with particular emphasis on the patterns of amino acids that define their cleavage sites.
