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Characterizing a SloR recognition element in the S.mutans mntH promoter region
Dental caries, caused by Streptococcus mutans, rank among the most prevalent chronic infectious diseases in the US and worldwide, affecting the majority of Americans and 34% of the global population. Intracellular metal ion homeostasis is maintained, in part by the 25kDa SloR metalloregulatory protein in S. mutans, that binds DNA when manganese is available to either repress or de-repress genes that contribute to S. mutans fitness and virulence potential. One of the genes regulated by SloR is mntH which encodes an ancillary transporter of manganese uptake. A recent in silico analysis of the mntH promoter region revealed a putative 18bp SloR recognition element or SRE comprised of two inverted hexameric repeats with a 6-6-6 binding motif. Electrophoretic mobility shift assays (EMSA) confirmed direct SloR binding to a 206-bp target probe on which the mntH promoter region is resident, as well as to at least two different binding sites on the 206-bp probe. However, a 55-bp DNA fragment that harbors the predicted SRE is insufficient for SloR binding. 5' serial extension fragments of the 55-bp sequence were tested in EMSAs to identify where on the 206bp mntH promoter fragment SloR binds. Accumulating evidence supports a 6-9-6 binding motif that is located upstream of the mntH coding sequence and housed on a 100-bp target probe that may constitute an SRE. The identification of this and other putative SREs in the mntH promoter region could help elucidate which sequences constitute SREs more broadly across the S. mutans genome and reveal the details of how mntH is regulated by SloR in S. mutans to maintain essential metal ion homeostasis.
History
Institution
- Middlebury College
Department or Program
- Molecular Biology and Biochemistry
Degree
- Bachelor of Arts
Academic Advisor
Dr. Grace SpataforaConditions
- Restricted to Campus