Biochemical characterization of the RECQ4 protein, mutated in Rothmund-Thomson syndrome.
Rothmund-Thomson syndrome (RTS) is an autosomal recessive disorder characterized by growth deficiency, skin and skeletal abnormalities, and a predisposition to cancer. Mutations in the RECQ4 gene, one of five human homologs of the E. coli recQ gene, have been identified in a subset of RTS patients. Cells derived from RTS patients show high levels of chromosomal instability, implicating this protein in the maintenance of genomic integrity. However, RECQ4 is the least characterized of the RecQ helicase family with regard to its molecular and catalytic properties. We have expressed the human RECQ4 protein in E. coli and purified it to near homogeneity. We show that RECQ4 has an ATPase function that is activated by DNA, with ssDNA being much more effective than dsDNA in this regard. We have determined that a DNA length of 60 nucleotides is required to maximally activate ATP hydrolysis by RECQ4, while the minimal site size for ssDNA binding by RECQ4 is between 20 and 40 nucleotides. Interestingly, RECQ4 possesses a single-strand DNA annealing activity that is inhibited by the single-strand DNA binding protein RPA. Unlike the previously characterized members of the RecQ family, RECQ4 lacks a detectable DNA helicase activity.
Macris
Margaret A
MA
Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, 333 Cedar St., C130 Sterling Hall of Medicine, New Haven, CT 06520-8024, USA.
Krejci
Lumir
L
Bussen
Wendy
W
Shimamoto
Akira
A
Sung
Patrick
P
D000251:Adenosine Triphosphatases / Q000737:chemistry; D000255:Adenosine Triphosphate / Q000737:chemistry; D000595:Amino Acid Sequence; D001483:Base Sequence; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004265:DNA Helicases / Q000235:genetics* / Q000378:metabolism*; D004260:DNA Repair; D004264:DNA Topoisomerases, Type I / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006868:Hydrolysis; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry; D011485:Protein Binding; D053484:RecQ Helicases; D051716:Replication Protein A / Q000378:metabolism; D011038:Rothmund-Thomson Syndrome / Q000235:genetics*; D013997:Time Factors
D004277:DNA, Single-Stranded; D009841:Oligonucleotides; D051716:Replication Protein A; D000255:Adenosine Triphosphate; D004247:DNA; D000251:Adenosine Triphosphatases; D004265:DNA Helicases; D053484:RecQ Helicases; D004264:DNA Topoisomerases, Type I