FIG 1.

Y. lipolytica nucleoids contain a novel type of HMG box-containing protein, YlMhb1. (A) Y. lipolytica mitochondria were fractionated, and mt-nucleoids were purified as described in Materials and Methods. Proteins (5 μg per lane) were separated by 12% SDS-PAGE and were visualized by silver staining. (B) DNA-binding proteins in mitochondrial fractions were detected using SDS-DNA-polyacrylamide gel electrophoresis as described previously (46). The 38-kDa band exhibiting strong DNA-binding activity most likely corresponds to the Nuc1 nuclease as observed in C. parapsilosis (46). (C) Schematic representation of the amino acid sequence of YlMhb1p highlighting the putative N-terminal mitochondrial targeting sequence, the peptide identified by N-terminal sequencing, and the positions of two putative HMG boxes predicted by the Phyre server (66).