Genetic orientation of homologues of the nisin U (a) and nisin-associated immunity and regulatory (b) genes found in S. infantarius subsp. infantarius. The up- and downstream genes are included, and from BlastP analysis, their theoretical functions are as follows: STRINF_01300, UDP-N-acetyl-d-glucosamine 2-epimerase; STRINF_01301, hypothetical protein; STRINF_01308, hypothetical ATP-binding protein; STRINF_01309, hypothetical membrane protein.