title: A unique unnatural base pair between a C analogue, pseudoisocytosine, and an A analogue, 6-methoxypurine, in replication.
abstract: Pseudoisocytidine, a C-nucleoside analogue of cytosine, has two possible isomers of the H1- and H3-forms. Enzymatic incorporation experiments confirmed the existence of the two isomers in solution, and the 2'-deoxyribonucleoside triphosphate of pseudoisocytosine (PIC) was incorporated into DNA opposite both guanine and 6-methoxypurine (M) by the Klenow fragment of Escherichia coli DNA polymerase I. In addition to the PIC*M pairing in replication, M also functioned as an A analogue and T was efficiently incorporated opposite M. Thus, the PIC*M pair is regarded as a base pair between a C analogue and an A analogue, and can mediate the interconversion between the G*C and A*T base pairs. The combination of PIC and M could be used as a G*C<-->A*T transition mutagen.
authors: Yokoyama CytoLogic Project, ERATO, JST and RIKEN Genomic Sciences Center, 2-1 Hirosawa, Wako-shi, 351-0198, Saitama, Japan. ihirao@postman.riken.go.jp
authors: Ichiro
authors: I
authors: Hirao
authors: Michiko
authors: M
authors: Kimoto
authors: Shun-ichi
authors: S
authors: Yamakage
authors: Masahide
authors: M
authors: Ishikawa
authors: Jun
authors: J
authors: Kikuchi
authors: Shigeyuki
authors: S
authors: Yokoyama
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology; D020029:Base Pairing; D001483:Base Sequence; D003562:Cytidine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology; D004256:DNA Polymerase I / Q000378:metabolism; D017931:DNA Primers; D004261:DNA Replication / Q000187:drug effects*; D004926:Escherichia coli / Q000201:enzymology; D007783:Lactones / Q000138:chemical synthesis* / Q000494:pharmacology; D008958:Models, Molecular; D008968:Molecular Conformation; D013698:Templates, Genetic
chemical_list: D017931:DNA Primers; D007783:Lactones; C465231:madurahydroxylactone; D003562:Cytidine; D004256:DNA Polymerase I; D000241:Adenosine