Function of the loop residue Thr792 in human DNA topoisomerase II alpha.
We studied the mutation effect of one of the putative loop residues Thr792 in human DNA topoisomerase II alpha (TOP2 alpha). Thr792 mutants were expressed from high or low copy plasmids in a temperature sensitive yeast strain deficient in TOP2 (top2-1). When expressed from a high copy plasmid, mutants with small side chains complemented the yeast defect; however, from a low copy plasmid, only wild-type, Ser, and Cys substitution mutants complemented the yeast defect. Interestingly, at the permissive temperature other mutants (e.g., Val, Gly, and Glu substitutions) showed the dominant negative effect to the top2-1 allele, which was not observed by the control alpha 4-helix mutants. T792E mutant was 10-fold less active than wild-type and the T792P had no decatenation activity in vitro. These results suggest that Thr792 in human TOP2 alpha is involved in enzyme catalysis.
Suda
Namiko
N
The Second Department of Surgery, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan.
Nakagawa
Yoshiyuki
Y
Kikuchi
Akihiko
A
Sawada
Masako
M
Takami
Yuko
Y
Funahashi
Hiro-omi
HO
Nakao
Akimasa
A
Yoshida
Shonen
S
Suzuki
Motoshi
M
D000951:Antigens, Neoplasm; D000970:Antineoplastic Agents / Q000494:pharmacology; D002384:Catalysis; D002455:Cell Division; D003545:Cysteine / Q000378:metabolism; D004250:DNA Topoisomerases, Type II / Q000737:chemistry*; D018076:DNA, Complementary / Q000378:metabolism; D004268:DNA-Binding Proteins; D004305:Dose-Response Relationship, Drug; D005656:Fungal Proteins / Q000378:metabolism; D005816:Genetic Complementation Test; D018698:Glutamic Acid / Q000378:metabolism; D005998:Glycine / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D000075223:Poly-ADP-Ribose Binding Proteins; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D013912:Threonine / Q000737:chemistry* / Q000378:metabolism; D014633:Valine / Q000378:metabolism
D000951:Antigens, Neoplasm; D000970:Antineoplastic Agents; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D000075223:Poly-ADP-Ribose Binding Proteins; D013912:Threonine; D018698:Glutamic Acid; D012694:Serine; D004250:DNA Topoisomerases, Type II; C000618811:TOP2A protein, human; D014633:Valine; D003545:Cysteine; D005998:Glycine