Crystallization and preliminary X-ray diffraction analysis of the mitochondrial transcription factor sc-mtTFB from Saccharomyces cerevisiae

Eukaryotic mitochondria contain a distinct mini-chromosome. In yeast, trans cription of the mitochondrial genome is mediated by a nuclear-encoded RNA p olymerase consisting of a single polypeptide core enzyme and a specificity factor termed sc-mtTFB which bears some similarity to bacterial sigma-facto rs. sc-mtTFB from Saccharomyces cerevisiae has been cloned, expressed, puri fied and crystallized. The crystals belong to the monoclinic space group C2 , with unit-cell parameters a = 89.7, b = 44.6, c = 98.9 Angstrom, beta = 1 10 degrees. Based on one molecule per asymmetric unit, the solvent content is estimated to be 48%. Small crystals of dimensions 0.01 x 0.05 x 0.13 mm diffract to at least 2.7 Angstrom resolution on a rotating-anode X-ray sour ce.