The DNA uptake ATPase PilF of Thermus thermophilus: a reexamination of the zinc content.

The DNA-translocator ATPase PilF of Thermus thermophilus HB27 is a hexamer built by six identical subunits. Despite the presence of a conserved zinc-binding site in every subunit, only one zinc atom per hexamer was found. Re-examination of the zinc content of PilF purified from cells grown in complex media with different lots of yeast extract revealed six zinc atoms per hexamer. These data demonstrate that the low zinc content reported before was most likely a result of zinc depletion of the yeast extract used.