Class II two-peptide lanthipeptide proteases: exploring LicTP for biotechnological applications

The enzymatic machinery involved in the biosynthesis of lantibiotic is an untapped source of proteases with different specificities. Lanthipeptide biosynthesis requires proteolysis of specific target sequences by known proteases, which are encoded by contiguous genes. Herein, the activity of lichenicidin A2 (LicA2) trimming proteases (LicP and LicT) was investigated in vivo. Firstly, the impact of some residues and the size of the peptide were evaluated. Then followed trials in which LicA2 leader was evaluated as a tag to direct production and secretion of other relevant peptides. Our results show that a negatively charged residue (preferably Glu) at cleavage site is important for LicP efficacy. Some mutations of the lichenicidin hexapeptide such as Val-4Ala, Asp-5Ala, Asn-6Ser, and the alteration of GG-motif to GA resulted in higher processing rates, indicating the possibility of improved lichenicidin production in Escherichia coli. More importantly, insulin A, amylin (non-lanthipeptides), and epidermin were produced and secreted to E. coli supernatant, when fused to the LicA2 leader peptide. This work aids in clarifying the activity of lantibiotic-related transporters and proteases and to evaluate their possible application in industrial processes of relevant compounds, taking advantage of the potential of microorganisms as biofactories. KEY POINTS: • LicM2 correct activity implies a negatively charged residue at position -1. • Hexapeptide mutations can increase the amount of fully processed Bliβ. • LicA2 leader peptide directs LicTP cleavage and secretion of other peptides.