Sequences of wild type and mutant att sites. attB, the wild type attB site for L54a integration into the S. aureus chromosome. attP, the wild type L54a attP site for integration at attB. The arrows indicate imperfect inverted repeats. The boxed regions signify the 18 bp core region shared between attP and attB. attP 1, L54a attP site with a 2 bp mutation (indicated in lower case lettering) carried on plasmid pLL3961. The attP 1 mutations allow for pLL3961 integration into the mutant attB 1 site. attP 2, an attP site with 5 mutations carried on plasmid pLL102. The attP 2 mutations allow for pLL102 integration into a mutant attB 2 site. attB 1, a mutant attB site with the same mutations as attP 1. The attB 1 site was placed in the chromosome of RN4220 between bps 911590 and 911591 (NCTC8325 genome) between the SAOUHSC00937 and SAOUHSC00938 orfs. The 21 bp knock in sequence, indicated by the line above the sequence, is bracketed by chromosomal DNA, indicated by the thick lines. The 5' to 3' orientations of SAOUHSC00937 and SAOUHSC00938 are indicated by the arrows. attB 2, a mutant attB site with the same mutations as attP 2. The attB 2 site was placed into the bacterial chromosome between the orfs SAOUHSC00009 and SAOUHSC00010 (bps 14208 and 14209). Labeling is the same as for attB 1.