Identification and Characterization of a novel mitochondrial histone-like protein in Physarum polycephalum

Abstract

Summary: Mitochondrial DNA(mtDNA)is packed into highly organized structures called mitochondrial nucleoids(mt-nucleoids). We identified and characterized a new mitochondrial histone-like protein, termed Glom(a protein inducing agglomeration of mitochondrial chromosome), from highly condensed mt-nucleoids of the true slime mold, Physarum polycephalum. This protein has a lysine-rich region with proline-rich domain in the N-terminal half and two HMG boxes in C-terminal half. Glom induced intensive DNA condensation without suppressing replication and transcription. The lysine-rich region was sufficient for the mtDNA condensation and the proline-rich domain was essential to keep those genetic activities. The expression of Glom also complemented the E.coli mutant lacking the bacterial histone-like protein HU and the HMG-boxes region of Glom was important for the complementation.