The ABC Transporter CclEFGH Facilitates the Production of the Circular Bacteriocin Carnocyclin A.

Carnocyclin A is a circular bacteriocin produced by Carnobacterium maltaromaticum UAL307. The carnocyclin A gene cluster cclBITCDAEFGH had been previously reported, and it was shown that transformation of C. maltaromaticum UAL26 with cclBITCDA resulted in immunity to, and low production of, carnocyclin A. Here, we demonstrate that full production of carnocyclin A in UAL26 transformants could be achieved when cclBITCDA was complemented with a second plasmid that contains cclEFGH. CclEFGH is a multicomponent ABC transporter that has similarity to As-48EFGH which is involved in the production of enterocin AS-48. Transformation of UAL26 containing cclBITCDA with deletion derivatives of cclEFGH did not increase the production of carnocyclin A, confirming the involvement of CclEFGH in bacteriocin production. Transformants of UAL26 containing cclEFGH showed a slight decrease in sensitivity to carnocyclin A, indicating that CclEFGH might also play a role in immunity.