Fig 1.

Schematic diagram of the integration and excision of SCCmec. Sequences are from S. aureus strain N315. Black and red double lines designate the chromosome and SCCmec, respectively. The orfX gene is marked as a blue dashed arrow. The att sites are marked as black short arrows. attR2 is an alternative site for excision. The sequences of att sites are shown below. The 8 identical bases are in boldface and underlined. The DNA sequences of att sites are black if they come solely from the chromosomal att site (attB) and red if they are from the circular, incoming SCCmec element (attS) or contained entirely within SCCmec (attR2). The arrows above sequences indicate inverted repeats that are either close together on the incoming circular element (attS) or at each end of the inserted element (attR1 and attL).