Chad Trumble

Date of Award


Degree Name

Master of Science


Biological Sciences

First Advisor

Dr. Maria E. Scott

Second Advisor

Dr. Silvia Rossbach

Third Advisor

Dr. Susan Stapleton

Access Setting

Masters Thesis-Campus Only


To examine the secreted protein profile of Shiga toxin-producing Escherichia coli (STEC) we developed a method to enrich for low abundance secreted proteins. Rotary evaporation in combination with conventional spin column concentration achieved protein enrichment 10-fold greater than that acquired by the traditional trichloroacetic acid protein precipitation method. Analysis of the enriched secreted protein fraction led to the discovery of a protein designated as YghJ. Genetic homology analysis revealed that YghJ is a serine/threonine phosphatase-like protein. Serine/threonine phosphatases have not previously been discovered in Escherichia coli and are rare in bacteria. The probable serine/threonine phosphatase activity of YghJ suggests that the protein may play a role in the regulation of stress factors produced by E. coli during times of nutrient deprivation.

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