Date of Award

Spring 2008

Document Type

Restricted Thesis

Terms of Use

© 2008 Nanelle R. Barash. All rights reserved. Access to this work is restricted to users within the Swarthmore College network and may only be used for non-commercial, educational, and research purposes. Sharing with users outside of the Swarthmore College network is expressly prohibited. For all other uses, including reproduction and distribution, please contact the copyright holder.

Degree Name

Bachelor of Arts


Biology Department

First Advisor

Amy Cheng Vollmer


The family of universal stress proteins (USPs) is nonspecifically upregulated in response to a wide variety of stresses, but its function is still unclear. The paradigmatic USP, UspA, is known to be phosphorylated on either a serine or threonine residue. This study created a library of site-specific alanine mutations of every serine and threonine residue within UspA. Given conservation and structural analysis, it seems likely that Serines 13, 16, 35, 34, 117,121, and 122, as well as Threonine 48, are the most likely targets of phosphorylation. After the development of a differential phenotype, the library of alleles can be used to determine the site of phosphorylation. Additionally, a synthetic lethality screen was initiated to uncover other protein-protein interactions involving UspA. yfJK, a gene within the cryptic prophage CP4-S7, was identified, as was QseC, the histidine kinase of the QseBC two-component system regulating flagellar biosynthesis in response to autoinducer-2. These results suggest that UspA could be involved in a global regulatory network controlling sigma factor expression, quorum sensing, and motility.