Molecular cloning of a cDNA encoding mouse DNA helicase B, which has homology to Escherichia coli RecD protein, and identification of a mutation in the DNA helicase B from tsFT848 temperature-sensitive DNA replication mutant cells.
DNA helicase B is a major DNA helicase in mouse FM3A cells. A temperature-sensitive mutant defective in DNA replication, tsFT848, isolated from FM3A cells, has a heat-labile DNA helicase B. In this study, we purified DNA helicase B from mouse FM3A cells and determined partial amino acid sequences of the purified protein. By using a DNA probe synthesized according to one of the partial amino acid sequences, a cDNA was isolated, which encoded a 121.5 kDa protein containing seven conserved motifs for DNA/RNA helicase superfamily members. A database search revealed similarity between DNA helicase B and the alpha subunit of exodeoxyribonuclease V of a number of prokaryotes including Escherichia coli RecD protein, but no homologous protein was found in yeast. The cDNA encoding DNA helicase B from tsFT848 was sequenced and a mutation was found between DNA/RNA helicase motifs IV and V.
Tada
S
S
Molecular Cell Biology Laboratory, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba-ku, Sendai, Miyagi 980-8578, Japan. tada@mail.pharm.tohoku.ac.jp
Kobayashi
T
T
Omori
A
A
Kusa
Y
Y
Okumura
N
N
Kodaira
H
H
Ishimi
Y
Y
Seki
M
M
Enomoto
T
T
D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D004265:DNA Helicases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D004261:DNA Replication / Q000235:genetics*; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics*; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins; D043211:Exodeoxyribonuclease V; D005090:Exodeoxyribonucleases / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013696:Temperature; D014407:Tumor Cells, Cultured
D018076:DNA, Complementary; D029968:Escherichia coli Proteins; D005090:Exodeoxyribonucleases; D043211:Exodeoxyribonuclease V; C468322:exodeoxyribonuclease V, E coli; D000251:Adenosine Triphosphatases; C484264:Helb protein, mouse; D004265:DNA Helicases