Preliminary X-ray crystallographic analysis of a soluble form of MntC, a periplasmic manganese-binding component of an ABC-type Mn transporter from Synechocystis sp. PCC 6803.

Manganese is recruited in microorganisms by way of ABC-type transporter systems. Here, the expression, purification and preliminary crystallographic analysis of a soluble form of the MntC solute-binding protein component of the MntABC manganese-import system from the cyanobacterium Synechococystis sp. PCC 6803 is reported. The protein (321 amino-acid residues) was expressed exclusively in inclusion bodies, which required unfolding and refolding in the presence of manganese prior to purification. The purified protein was crystallized in the presence of PEG and zinc. The crystals belong to space group P6222, with unit-cell parameters a = b = 128.1, c = 90.0 A and a single molecule in the asymmetric unit. The crystals diffract to 2.6 A under cryoconditions using synchrotron radiation.