Date of Award

Fall 2013

Degree Type


Degree Name

Doctor of Philosophy (PhD)


Biological Science

First Advisor

Jeffrey T. Bolin

Second Advisor

Dinesh A. Yernool

Committee Chair

Jeffrey T. Bolin

Committee Member 1

Dinesh A. Yernool

Committee Member 2

Eric L. Baker

Committee Member 3

William A. Cramer


To better understand a class of transporters known as Calcium/Cation Antiporters (CaCAs), the bacterial calcium/proton antiporter CAXCK31 was purified and characterized. New methods were developed for its heterologous overexpression and purification. These methods help to define stress responses to toxic membrane overproduction in E. coli and may be broadly applicable to studies of membrane proteins. The results from a variety of biochemical and biophysical experiments demonstrated that CAXCK31 exists as a dimer in the membrane and can be purified in the dimeric state. The methods used include chemical cross-linking, FRET, and SEC-MALS. In addition, various transport properties of CAXCK31, including substrate selectivity, pH dependence, and transport rates, have been characterized for the first time.