TIP49b, a new RuvB-like DNA helicase, is included in a complex together with another RuvB-like DNA helicase, TIP49a.
We previously reported that TIP49a is a novel mammalian DNA helicase showing structural similarity with the bacterial recombination factor RuvB. In this study, we isolated a new TIP49a-related gene, termed TIP49b, from human and yeast cells. TIP49b also resembled RuvB, thus suggesting that TIP49a and TIP49b are included in a gene family. Like TIP49a, TIP49b was abundantly expressed in the testis and thymus. Enzyme assays revealed that TIP49b was an single-stranded DNA-stimulated ATPase and ATP-dependent DNA helicase. Most of the enzymatic properties of TIP49b were the same as those of TIP49a, whereas the polarity of TIP49b DNA helicase activity (5' to 3') was the opposite to that of TIP49a. TIP49b and TIP49a bound to each other and were included in the same complex of approximately 700 kDa in a cell. We found that TIP49b was an essential gene for the growth of Saccharomyces cerevisiae, as is the TIP49a gene, suggesting that TIP49b does not complement the TIP49a function and vice versa. From these observations, we suggest that TIP49b plays an essential role in the cellular processes involved in DNA metabolism.
Kanemaki
M
M
Department of Biology, Faculty of Science, Chiba University, CREST Japan Science and Technology Corp., 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
Kurokawa
Y
Y
Matsu-ura
T
T
Makino
Y
Y
Masani
A
A
Okazaki
K
K
Morishita
T
T
Tamura
T A
TA
D000074183:ATPases Associated with Diverse Cellular Activities; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D003001:Cloning, Molecular; D004265:DNA Helicases / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D005057:Eukaryotic Cells / Q000201:enzymology; D020043:Genes, Essential; D005800:Genes, Fungal; D006801:Humans; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D011485:Protein Binding; D012441:Saccharomyces cerevisiae / Q000235:genetics; D014018:Tissue Distribution
D001426:Bacterial Proteins; D002352:Carrier Proteins; D018076:DNA, Complementary; D046911:Macromolecular Substances; D009687:Nuclear Proteins; C061260:RuvB protein, Bacteria; D000251:Adenosine Triphosphatases; D000074183:ATPases Associated with Diverse Cellular Activities; D004265:DNA Helicases; C486549:RUVBL1 protein, human; C122079:RUVBL2 protein, human