Outstanding Undergraduate Poster Presentation
YdfM: A Possible Bacillus
subtilis Manganese Exporter
Schoenberger, Courtney Larson, Scott E. Gabriel
Viterbo University, La Crosse, WI
Cells delicately balance intracellular metal leveals. Metals
are essential cofactors of many required enzymes, yet free metals can cause
oxidative damage or become toxic. In order to maintain this balance, Bacillus
subtilis has a family of metalloregulatory proteins that regulate the
expression of a wide range of genes involved in controlling metal levels.
Due to our interest in metalloregulation in B. subtilis, YdfM, an uncharacterized
hypothetical metal exporter was chosen for study. A similarity search using the YdfM sequence showed
FieF, from Escherichia coli, possessed
significant homology. Since FieF has been
previously shown to have an iron export function, we hypothesized that YdfM may
play a similar role in B. subtilis. Our results will show that YdfM to our
surprise plays no apparent role in iron export and is likely involved in
manganese export instead.
A ydfM null mutant
was created by long flanking homology.
Growth curves were performed with this knockout strain and wild-type B. subtilis. For both high and low iron concentrations,
the wild-type and knockout strains showed no apparent growth difference. To determine if longer exposure to iron would
result in a phenotype, zone of inhibition studies were performed. These studies also showed no significant
difference. Since phenotypic studies of the ydfM
mutant gave no insight into the gene’s function, we decided to create a ydfM promoter fusion to study its
regulation. After exposure to a panel of metals in varying concentrations, only
manganese resulted in up regulation of the gene’s expression.