The N-terminus of the human RecQL4 helicase is a homeodomain-like DNA interaction motif.
The RecQL4 helicase is involved in the maintenance of genome integrity and DNA replication. Mutations in the human RecQL4 gene cause the Rothmund-Thomson, RAPADILINO and Baller-Gerold syndromes. Mouse models and experiments in human and Xenopus have proven the N-terminal part of RecQL4 to be vital for cell growth. We have identified the first 54 amino acids of RecQL4 (RecQL4_N54) as the minimum interaction region with human TopBP1. The solution structure of RecQL4_N54 was determined by heteronuclear liquid-state nuclear magnetic resonance (NMR) spectroscopy (PDB 2KMU; backbone root-mean-square deviation 0.73 Å). Despite low-sequence homology, the well-defined structure carries an overall helical fold similar to homeodomain DNA-binding proteins but lacks their archetypical, minor groove-binding N-terminal extension. Sequence comparison indicates that this N-terminal homeodomain-like fold is a common hallmark of metazoan RecQL4 and yeast Sld2 DNA replication initiation factors. RecQL4_N54 binds DNA without noticeable sequence specificity yet with apparent preference for branched over double-stranded (ds) or single-stranded (ss) DNA. NMR chemical shift perturbation observed upon titration with Y-shaped, ssDNA and dsDNA shows a major contribution of helix α3 to DNA binding, and additional arginine side chain interactions for the ss and Y-shaped DNA.
Research Group Biomolecular NMR Spectroscopy, Leibniz Institute for Age Research-Fritz Lipmann Institute, Beutenbergstr. 11, Jena, Germany.
Oliver
O
Ohlenschläger
Anja
A
Kuhnert
Annerose
A
Schneider
Sebastian
S
Haumann
Peter
P
Bellstedt
Heidi
H
Keller
Hans-Peter
HP
Saluz
Peter
P
Hortschansky
Frank
F
Hänel
Frank
F
Grosse
Matthias
M
Görlach
Helmut
H
Pospiech
D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000378:metabolism; D004247:DNA / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D018398:Homeodomain Proteins / Q000737:chemistry*; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D009687:Nuclear Proteins / Q000378:metabolism; D054730:Protein Interaction Domains and Motifs; D053484:RecQ Helicases / Q000737:chemistry* / Q000378:metabolism; D016415:Sequence Alignment
D002352:Carrier Proteins; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; C110513:TOPBP1 protein, human; D004247:DNA; C506731:RECQL4 protein, human; D053484:RecQ Helicases