title: Glom is a novel mitochondrial DNA packaging protein in Physarum polycephalum and causes intense chromatin condensation without suppressing DNA functions.
abstract: Mitochondrial DNA (mtDNA) is packed into highly organized structures called mitochondrial nucleoids (mt-nucleoids). To understand the organization of mtDNA and the overall regulation of its genetic activity within the mt-nucleoids, we identified and characterized a novel mtDNA packaging protein, termed Glom (a protein inducing agglomeration of mitochondrial chromosome), from highly condensed mt-nucleoids of the true slime mold, Physarum polycephalum. This protein could bind to the entire mtDNA and package mtDNA into a highly condensed state in vitro. Immunostaining analysis showed that Glom specifically localized throughout the mt-nucleoid. Deduced amino acid sequence revealed that Glom has a lysine-rich region with proline-rich domain in the N-terminal half and two HMG boxes in C-terminal half. Deletion analysis of Glom revealed that the lysine-rich region was sufficient for the intense mtDNA condensation in vitro. When the recombinant Glom proteins containing the lysine-rich region were expressed in Escherichia coli, the condensed nucleoid structures were observed in E. coli. Such in vivo condensation did not interfere with transcription or replication of E. coli chromosome 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. Our results suggest that Glom is a new mitochondrial histone-like protein having a property to cause intense DNA condensation without suppressing DNA functions.
authors.affiliation: Department of Biology, Faculty of Science, Ochanomizu University, Tokyo, Japan. narie@cc.ocha.ac.jp
authors.forename: Narie
authors.initials: N
authors.lastname: Sasaki
authors.forename: Haruko
authors.initials: H
authors.lastname: Kuroiwa
authors.forename: Chikako
authors.initials: C
authors.lastname: Nishitani
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Takano
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Higashiyama
authors.forename: Tamaki
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Yuki
authors.initials: Y
authors.lastname: Shirai
authors.forename: Atsushi
authors.initials: A
authors.lastname: Sakai
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Kawano
authors.forename: Kimiko
authors.initials: K
authors.lastname: Murakami-Murofushi
authors.forename: Tsuneyoshi
authors.initials: T
authors.lastname: Kuroiwa
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002843:Chromatin / Q000378:metabolism; D003001:Cloning, Molecular; D004261:DNA Replication; D004272:DNA, Mitochondrial / Q000235:genetics / Q000378:metabolism*; D021902:Enterobacter aerogenes / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D009154:Mutation; D016839:Physarum polycephalum / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000502:physiology; D020539:Sequence Analysis, Protein; D014158:Transcription, Genetic
chemical_list: D002843:Chromatin; D004272:DNA, Mitochondrial; D005656:Fungal Proteins