Distinctive properties of signal sequences from bacterial lipoproteins.

We have compared a number of attributes (hydrophobicity, amino acid size, charge and secondary structure propensities) of signal sequences from bacterial lipoproteins with the same attributes of signal peptides from other prokaryotic proteins (non-lipoproteins). Lipoprotein leader sequences tend to be shorter, more hydrophobic and bulky, and they have stronger conformational preferences, the most conspicuous being a predicted beta-turn comprising positions 2 or 3 of the mature protein. Another distinctive feature is a maximum in the local energy profile between positions -1 and +2. With one exception (beta-lactamase III), the lipoproteins do not have Pro in their signal peptides, and they tend to have fewer Ser and Thr but more Gly than non-lipoproteins. Lipoproteins also lack a net negative charge in the N-terminal regions of the mature proteins. The signal peptides of the bacteriocin plasmid-coded lysis proteins appear to be unique in that they have all the ascribed features of lipoprotein signals; these characteristics can be used to guide signal peptide mutagenesis experiments and to construct new secretion vehicles.