Early zygote-specific nuclease in mitochondria of the true slime mold Physarum polycephalum.
The active, selective digestion of mtDNA from one parent is a possible molecular mechanism for the uniparental inheritance of mtDNA. In Physarum polycephalum, mtDNA is packed by DNA-binding protein Glom, which packs mtDNA into rod-shaped mt-nucleoids. After the mating, mtDNA from one parent is selectively digested, and the Glom began to disperse. Dispersed Glom was retained for at least 6 h after mtDNA digestion, but disappeared completely by about 12 h after mixing two strains. We identified two novel nucleases using DNA zymography with native-PAGE and SDS-PAGE. One is a Ca2+-dependent, high-molecular-weight nuclease complex (about 670 kDa), and the other is a Mn2+-dependent, high-molecular-weight nuclease complex (440-670 kDa); the activity of the latter was detected as a Mn2+-dependent, 13-kDa DNase band on SDS-PAGE. All mitochondria isolated from myxamoebae had mt-nucleoids, whereas half of the mitochondria isolated from the zygotes at 12 h after mixing had lost the mt-nucleoids. The activity of the Mn2+-dependent nuclease in the isolated mitochondria was detected at least 8 h after mixing of two strains. The timing and localization of the Mn2+-dependent DNase activity matched the selective digestion of mtDNA.
Moriyama
Yohsuke
Y
Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Bldg. FSB-601, 5-1-5 Kashiwanoha, Kashiwa, 277-8562, Chiba, Japan.
Yamazaki
Tomokazu
T
Nomura
Hideo
H
Sasaki
Narie
N
Kawano
Shigeyuki
S
D000818:Animals; D002850:Chromatography, Gel; D004272:DNA, Mitochondrial / Q000378:metabolism*; D016054:DNA, Protozoan / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D003851:Deoxyribonucleases / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D008928:Mitochondria / Q000201:enzymology*; D016839:Physarum polycephalum / Q000166:cytology / Q000201:enzymology*; D015800:Protozoan Proteins / Q000378:metabolism*; D015053:Zygote / Q000201:enzymology*
D004272:DNA, Mitochondrial; D016054:DNA, Protozoan; D004268:DNA-Binding Proteins; D015800:Protozoan Proteins; D003851:Deoxyribonucleases