Staphylococcus aureus
pandemic clone USA300 has, in addition to its constitutive arginine catabolism (
arc)
gene cluster, an arginine catabolism mobile element (ACME) carrying another such cluster, which gives this clone
advantages in colonisation and infection. Gene
arcR, which encodes an oxygen-sensitive transcriptional regulator, is
inside ACME and downstream of the constitutive
arc gene cluster, and this situation may have an impact on its activation.
Different relative expression behaviours are proven here for
arcRACME and the
arcACME operon compared to the
constitutive ones. We also show that the artificially expressed recombinant ArcR
ACME protein binds to the promoter
region of the
arcACME operon; this mechanism can be related to a positive feedback model, which may be responsible
for increased anaerobic survival of the USA300 clone during infection-related processes.