1.C.53 The Lactocyclicin Q (Lactocyclicin Q) Family

Lactococcus sp. strain QU 12, isolated from cheese, produces a cyclic bacteriocin termed lactocyclicin Q (Sawa et al., 2009). Lactocyclicin Q was purified from culture supernatant and has a unique antimicrobial spectrum, high level of protease resistance, and heat stability compared to other reported bacteriocins of lactic acid bacteria. This compound is composed of 61 aas that have a cyclic structure with linkage between the N and C termini by a peptide bond. It shows little similarity to any other antimicrobial peptides, including cyclic bacteriocins, but shows significant similarity to small proteins from Bacillus coagulans (EEN93214; 38% identity) and Paenibacillus larvae (ZP_02326427; 36% identity). It has 1 or 2 TMSs.

The second subfamily (1.C.53.2) consists of bacterial proteins, all of which probably have 2 TMSs, fairly centrally located, but variable is size.  They derive from a variety of bacteria and are distantly related to the proteins in subfamily 1. The annotations for these proteins vary considerable from DUF1269, general stress protein, ChaB family protein, and permease.

The reaction presumed to be catalyzed by Lactocyclicin Q is:

ions (in) ⇌ ions (out)