RECA plays a dual role in the maintenance of chloroplast genome stability in Physcomitrella patens.
Chloroplast DNA (cpDNA) encodes essential genes for chloroplast functions, including photosynthesis. Homologous recombination occurs frequently in cpDNA; however, its significance and underlying mechanism remain poorly understood. In this study, we analyzed the role of a nuclear-encoded chloroplast-localized homolog of RecA recombinase, which is a key factor in homologous recombination in bacteria, in the moss Physcomitrella patens. Complete knockout (KO) of the P. patens chloroplast RecA homolog RECA2 caused a modest growth defect and conferred sensitivity to methyl methanesulfonate and UV. The KO mutant exhibited low recovery of cpDNA from methyl methanesulfonate damage, suggesting that RECA2 knockout impairs repair of damaged cpDNA. The RECA2 KO mutant also exhibited reduced cpDNA copy number and an elevated level of cpDNA molecule resulting from aberrant recombination between short dispersed repeats (13-63 bp), indicating that the RECA2 KO chloroplast genome was destabilized. Taken together, these data suggest a dual role for RECA2 in the maintenance of chloroplast genome stability: RECA2 suppresses aberrant recombination between short dispersed repeats and promotes repair of damaged DNA.
Department of Life Science, College of Science, Rikkyo (St Paul's) University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo, 171-8501, Japan.|Department of Botany, Graduate School of Science, Kyoto University, Oiwake-cho, Kita-Shirakawa, Sakyo-ku, Kyoto, 606-8502, Japan.
Masaki
M
Odahara
Department of Life Science, College of Science, Rikkyo (St Paul's) University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo, 171-8501, Japan.
Takayuki
T
Inouye
Department of Botany, Graduate School of Science, Kyoto University, Oiwake-cho, Kita-Shirakawa, Sakyo-ku, Kyoto, 606-8502, Japan.
Yoshiki
Y
Nishimura
Department of Life Science, College of Science, Rikkyo (St Paul's) University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo, 171-8501, Japan.
Yasuhiko
Y
Sekine
D019068:Bryopsida / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D056915:DNA Copy Number Variations; D004249:DNA Damage / Q000235:genetics; D004260:DNA Repair; D055786:Gene Knockout Techniques; D054628:Genome, Chloroplast; D018745:Genome, Plant; D042822:Genomic Instability; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D009154:Mutation; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011938:Rec A Recombinases / Q000235:genetics / Q000378:metabolism*; D014466:Ultraviolet Rays
D010940:Plant Proteins; D008741:Methyl Methanesulfonate; D011938:Rec A Recombinases
DNA repair; Physcomitrella patens; RecA; chloroplast genome; dispersed repeats; recombination