Structural insight of DNA topoisomerases I from camptothecin-producing plants revealed by molecular dynamics simulations.
DNA topoisomerase I (Top1) catalyzes changes in DNA topology by cleaving and rejoining one strand of the double stranded (ds)DNA. Eukaryotic Top1s are the cellular target of the plant-derived anticancer indole alkaloid camptothecin (CPT), which reversibly stabilizes the Top1-dsDNA complex. However, CPT-producing plants, including Camptotheca acuminata, Ophiorrhiza pumila and Ophiorrhiza liukiuensis, are highly resistant to CPT because they possess point-mutated Top1. Here, the adaptive convergent evolution is reported between CPT production ability and mutations in their Top1, as a universal resistance mechanism found in all tested CPT-producing plants. This includes Nothapodytes nimmoniana, one of the major sources of CPT. To obtain a structural insight of the resistance mechanism, molecular dynamics simulations of CPT- resistant and -sensitive plant Top1s complexed with dsDNA and topotecan (a CPT derivative) were performed, these being compared to that for the CPT-sensitive human Top1. As a result, two mutations, Val617Gly and Asp710Gly, were identified in O. pumila Top1 and C. acuminata Top1, respectively. The substitutions at these two positions, surprisingly, are the same as those found in a CPT derivative-resistant human colon adenocarcinoma cell line. The results also demonstrated an increased linker flexibility of the CPT-resistant Top1, providing an additional explanation for the resistance mechanism found in CPT-producing plants. These mutations could reflect the long evolutionary adaptation of CPT-producing plant Top1s to confer a higher degree of resistance.
Department of Biochemistry, Faculty of Science, Chulalongkorn University, Thailand; Department of Molecular Biology and Biotechnology, Graduate School of Pharmaceutical Sciences, Chiba University, Japan. Electronic address: supaart.s@chula.ac.th.
Supaart
S
Sirikantaramas
Department of Biochemistry, Faculty of Science, Chulalongkorn University, Thailand.
Arthitaya
A
Meeprasert
Department of Biochemistry, Faculty of Science, Chulalongkorn University, Thailand.
Thanyada
T
Rungrotmongkol
Department of Physical Chemistry, Graduate School of Pharmaceutical Sciences, Chiba University, Japan.
Hideyoshi
H
Fuji
Department of Physical Chemistry, Graduate School of Pharmaceutical Sciences, Chiba University, Japan.
Tyuji
T
Hoshino
Department of Molecular Biology and Biotechnology, Graduate School of Pharmaceutical Sciences, Chiba University, Japan; Faculty of Pharmaceutical Sciences, Hoshi University, Japan.
Hiroshi
H
Sudo
Department of Molecular Biology and Biotechnology, Graduate School of Pharmaceutical Sciences, Chiba University, Japan.
Mami
M
Yamazaki
Department of Molecular Biology and Biotechnology, Graduate School of Pharmaceutical Sciences, Chiba University, Japan. Electronic address: ksaito@faculty.chiba-u.jp.
Kazuki
K
Saito
D000595:Amino Acid Sequence; D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry / Q000494:pharmacology; D005075:Biological Evolution; D029769:Camptotheca / Q000737:chemistry*; D002166:Camptothecin / Q000096:biosynthesis* / Q000737:chemistry / Q000494:pharmacology; D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D006801:Humans; D056004:Molecular Dynamics Simulation; D015394:Molecular Structure; D009154:Mutation; D011487:Protein Conformation; D059004:Topoisomerase I Inhibitors / Q000737:chemistry / Q000494:pharmacology
D000972:Antineoplastic Agents, Phytogenic; D059004:Topoisomerase I Inhibitors; D004264:DNA Topoisomerases, Type I; C528909:TOP1 protein, human; D002166:Camptothecin
Camptothecin; Icacinaceae; Mutation; Nothapodytes nimmoniana; Resistance; Topoisomerase I