Browsing by Author "Stevenson, Brian"

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    Borrelia burgdorferi SpoVG DNA- and RNA-Binding Protein Modulates the Physiology of the Lyme Disease Spirochete
    Savage, Christina R.; Jutras, Brandon L.; Bestor, Aaron; Tilly, Kit; Rosa, Patricia A.; Tourand, Yvonne; Stewart, Philip E.; Brissette, Catherine A.; Stevenson, Brian (American Society for Microbiology, 2018-06-01)
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    BpaB, a novel protein encoded by the Lyme disease spirochete’s cp32 prophages, binds to erp Operator 2 DNA
    Burns, Logan H.; Adams, Claire A.; Riley, Sean P.; Jutras, Brandon L.; Bowman, Amy; Chenail, Alicia M.; Cooley, Anne E.; Haselhorst, Laura A.; Moore, Alisha M.; Babb, Kelly; Fried, Michael G.; Stevenson, Brian (Oxford University Press, 2010)
    Borrelia burgdorferi produces Erp outer surface proteins throughout mammalian infection, but represses their synthesis during colonization of vector ticks. A DNA region 50 of the start of erp transcription, Operator 2, was previously shown to be essential for regulation of expression. We now report identification and characterization of a novel erp Operator 2-binding protein, which we named BpaB. erp operons are located on episomal cp32 prophages, and a single bacterium may contain as many as 10 different cp32s. Each cp32 family member encodes a unique BpaB protein, yet the three tested cp32-encoded BpaB alleles all bound to the same DNA sequence. A 20-bp region of erp Operator 2 was determined to be essential for BpaB binding, and initial protein binding to that site was required for binding of additional BpaB molecules. A 36-residue region near the BpaB carboxy terminus was found to be essential for high-affinity DNA-binding. BpaB competed for binding to erp Operator 2 with a second B. burgdorferi DNAbinding protein, EbfC. Thus, cellular levels of free BpaB and EbfC could potentially control erp transcription levels.
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    Eubacterial SpoVG Homologs Constitute a New Family of Site-Specific DNA-Binding Proteins
    Jutras, Brandon L.; Chenail, Alicia M.; Rowland, Christi L.; Carroll, Dustin W.; Miller, M. Clarke; Bykowski, Tomasz; Stevenson, Brian (PLOS, 2013-06-20)
    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 a-helix contributes to DNA sequence specificity. Two additional, highly conserved amino acid residues on an adjacent b-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.
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    The Lyme disease spirochete's BpuR DNA/RNA-binding protein is differentially expressed during the mammal-tick infectious cycle, which affects translation of the SodA superoxide dismutase
    Jutras, Brandon L.; Savage, Christina R.; Arnold, William K.; Lethbridge, Kathryn G.; Carroll, Dustin W.; Tilly, Kit; Bestor, Aaron; Zhu, Haining; Seshu, Janakiram; Zuckert, Wolfram R.; Stewart, Philip E.; Rosa, Patricia A.; Brissette, Catherine A.; Stevenson, Brian (2019-07)
    When the Lyme disease spirochete, Borrelia burgdorferi, transfers from a feeding tick into a human or other vertebrate host, the bacterium produces vertebrate-specific proteins and represses factors needed for arthropod colonization. Previous studies determined that the B. burgdorferi BpuR protein binds to its own mRNA and autoregulates its translation, and also serves as co-repressor of erp transcription. Here, we demonstrate that B. burgdorferi controls transcription of bpuR, expressing high levels of bpuR during tick colonization but significantly less during mammalian infection. The master regulator of chromosomal replication, DnaA, was found to bind specifically to a DNA sequence that overlaps the bpuR promoter. Cultured B. burgdorferi that were genetically manipulated to produce elevated levels of BpuR exhibited altered levels of several proteins, although BpuR did not impact mRNA levels. Among these was the SodA superoxide dismutase, which is essential for mammalian infection. BpuR bound to sodA mRNA in live B. burgdorferi, and a specific BpuR-binding site was mapped 5 ' of the sodA open reading frame. Recognition of posttranscriptional regulation of protein levels by BpuR adds another layer to our understanding of the B. burgdorferi regulome, and provides further evidence that bacterial protein levels do not always correlate directly with mRNA levels.
  • The Lyme disease spirochete’s BpuR DNA- / RNA-binding protein is differentially expressed during the mammal-tick infectious cycle, and affects translation of the SodA superoxide dismutase
    Jutras, Brandon L.; Arnold, William; Savage, Christina R.; Tilly, Kit; Beastor, Aaron; Rosa, Patti; Brissette, Catherine A.; Stevenson, Brian (Wiley, 2019-09)