Yusuke Kobayashi, first author of Holliday junction resolvase MOC1 maintains plastid and mitochondrial genome integrity in algae and bryophytes
Current position: Assistant Professor, College of Science, Graduate School of Science and Engineering, Ibaraki University
Education: Ph.D. in Science. Graduate School of Science, Kyoto University, Kyoto, Japan
Non-scientific interests: gardening, beer, playing with cats
Brief bio: Plastids and mitochondria were established in eukaryotic cells by endosymbiotic events of alpha-proteobacterial and cyanobacterial ancestors, respectively. Both organelles possess their own genomes and proliferate by division of preexisting ones, which is reminiscent of their bacterial ancestors. I started my research to understand the molecular basis underlying the replication, repair, segregation and inheritance of plant organelle DNA at Prof. Toshiharu Shikanai’s lab in Kyoto University. I identified Monokaryotic Chloroplast 1 (MOC1), which is crucial for the faithful segregation of plastid DNA (ptDNA). Our in vitro analysis revealed that MOC1 specifically cleave a Holliday junction (HJ), which is formed during homologous recombination (HR), suggesting that MOC1 cleaves HJs to terminate HR and segregate ptDNA faithfully (Kobayashi et al., Science 2017). However, how MOC1 functions in vivo has not been investigated. Furthermore, although Cruciform cutting endonuclease 1 (CCE1) was identified as a mitochondrial DNA (mtDNA) HJ resolvase in yeasts, homologs or other mitochondrial HJ resolvases have never been identified in other eukaryotes, including animals and plants. In the present study, we show that MOC1 acts for recombination surveillance of plastid and mitochondrial DNA by preventing ectopic recombination between short dispersed repeats in the green alga Chlamydomonas reinhardtii and the moss Physcomitrella patens. Now, I’m trying to decode the mystery of plant organelle DNA replication, repair, segregation and inheritance with my students.