Anti-HIV siamycin I directly inhibits autophosphorylation activity of the bacterial FsrC quorum sensor and other ATP-dependent enzyme activities.

Abstract

Siamycin I disrupts growth and quorum sensing in Enterococcus faecalis. Using purified intact protein,
we demonstrate here that quorum membrane sensor kinase FsrC is a direct target of siamycin I,
reducing pheromone-stimulated autophosphorylation activity by up to 91%. Inhibition was noncompetitive with ATP as substrate. Other ATP-binding enzymes were also inhibited, including nine other membrane sensor kinases of E. faecalis, Rhodobacter sphaeroides PrrB, porcine Na+-dependent ATPase and the catalytic subunit of bovine protein kinase A, but not bacterial b-galactosidase, confirming targeted inhibition of a wide range of ATP dependent reactions, and elucidating a likely mechanism underlying the lethality of the inhibitor.