Molecular cloning of the gene encoding nuclear DNA helicase II. A bovine homologue of human RNA helicase A and Drosophila Mle protein.
Nuclear DNA helicase II (NDH II) unwinds both DNA and RNA (Zhang, S., and Grosse, F. (1994) Biochemistry 33, 3906-3912). Here, we report on the molecular cloning and sequence determination of the complementary DNA (cDNA) coding for this DNA and RNA helicase. The full-length cDNA sequence was derived from overlapping clones that were detected by immunoscreening of a calf thymus cDNA library in bacteriophage lambda gt11. This cDNA was 4,528 bases in length, which corresponded well with a 4.5-4.7-kilobase-long mRNA as detected by Northern blot analysis. The open reading frame of NDH II cDNA predicts a polypeptide of 1287 amino acids and a calculated molecular mass of 141,854 daltons. NDH II is related to a group of nucleic acid helicases from the DEAD/H box family II, with the signature motif DEIH in domain II. Two further proteins of this family, i.e. human RNA helicase A and Drosophila Maleless (Mle) protein, were found to be highly homologous to NDH II. With RNA helicase A, there was 91.5% identity and 95.5% similarity between the amino acid residues; with Mle protein, we observed a 50% identity and an 85% similarity. Antibodies against human RNA helicase A cross-reacted with NDH II, further supporting that NDH II is the bovine homologue of human RNA helicase A. Immunofluorescence studies revealed a mainly nuclear localization of NDH II. A role for NDH II in nuclear DNA and RNA metabolism is suggested.
Zhang
S
S
Heinrich-Pette-Institut für Experimentelle Virologie und Immunologie, Hamburg, Germany.
Maacke
H
H
Grosse
F
F
D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000302:isolation & purification; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002417:Cattle; D002451:Cell Compartmentation; D002467:Cell Nucleus / Q000201:enzymology*; D002868:Chromosomal Proteins, Non-Histone; D003001:Cloning, Molecular; D004265:DNA Helicases / Q000235:genetics*; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D005455:Fluorescent Antibody Technique; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics; D020365:RNA Helicases; D012316:RNA Nucleotidyltransferases / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics
D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; C070837:mle protein, Drosophila; D012316:RNA Nucleotidyltransferases; D000251:Adenosine Triphosphatases; D004265:DNA Helicases; D020365:RNA Helicases