Preliminary crystallographic studies of yeast mitochondrial peripheral membrane protein Tim44p.

Protein translocations across mitochondrial membranes play critical roles in mitochondrion biogenesis. Protein transport from the cell cytosol to the mitochondrial matrix is carried out by the translocase of the outer membrane (TOM) complex and the translocase of the inner membrane (TIM) complexes. Tim44p is an essential mitochondrial peripheral membrane protein and a major component of the TIM23 translocon. To investigate the mechanism by which Tim44p functions in the TIM23 translocon to deliver the mitochondrial protein precursors, the yeast Tim44p was crystallized. The crystals diffract to 3.2 A using a synchrotron X-ray source and belong to space group P6(3)22, with unit-cell parameters a = 124.25, c = 77.83 A. There is one Tim44p molecule in one asymmetric unit, which corresponds to a solvent content of approximately 43%. Structure determination by MAD methods is under way.