Abstract
A site-specific DNA-binding protein was purified from Borrelia burgdorferi cytoplasmic extracts, and determined to be a member of the highly conserved SpoVG family. This is the first time a function has been attributed to any of these ubiquitous bacterial proteins. Further investigations into SpoVG orthologues indicated that the Staphylococcus aureus protein also binds DNA, but interacts preferentially with a distinct nucleic acid sequence. Site-directed mutagenesis and domain swapping between the S. aureus and B. burgdorferi proteins identified that a 6-residue stretch of the SpoVG α-helix contributes to DNA sequence specificity. Two additional, highly conserved amino acid residues on an adjacent β-sheet are essential for DNA-binding, apparently by contacts with the DNA phosphate backbone. Results of these studies thus identified a novel family of bacterial DNA-binding proteins, developed a model of SpoVG-DNA interactions, and provide direction for future functional studies on these wide-spread proteins.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Bacterial Proteins / chemistry
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Bacterial Proteins / genetics
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Bacterial Proteins / metabolism*
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Binding Sites / genetics
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Binding, Competitive
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Borrelia burgdorferi / genetics
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Borrelia burgdorferi / metabolism*
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DNA, Bacterial / chemistry
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DNA, Bacterial / genetics
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DNA, Bacterial / metabolism
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DNA-Binding Proteins / chemistry
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism*
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Eubacterium / classification
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Eubacterium / genetics
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Eubacterium / metabolism
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Molecular Sequence Data
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Mutagenesis, Site-Directed
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Nucleotide Motifs / genetics
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Protein Binding
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Protein Multimerization
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Protein Structure, Secondary
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Sequence Homology, Amino Acid
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Species Specificity
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Staphylococcus aureus / genetics
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Staphylococcus aureus / metabolism*
Substances
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Bacterial Proteins
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DNA, Bacterial
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DNA-Binding Proteins
Grants and funding
This work was supported by a grant from the National Research Fund for Tick-Borne Diseases to B. Stevenson. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.