Date of Completion

Spring 5-8-2011

Thesis Advisor(s)

R. Thane Papke

Department

Cell Biology

Disciplines

Cell and Developmental Biology | Cell Biology | Molecular Biology

Abstract

Bacteria coordinate cell density dependent behaviors by communicating through chemical intermediaries in a process called quorum sensing. In a bacterial culture, individual cells will constitutively produce signal molecules, termed autoinducers, and export them into the environment. When the concentration of autoinducers reaches a threshold, the cells sense that they are in a specific situation, which requires the upregulation of certain genes. This upregulation causes the bacteria to produce proteins that allow them to take part in a coordinated population-wide behavior.

In bacteria that are naturally competent, or capable of importing DNA from the environment, the expression of competence genes is often regulated by quorum sensing. Recent evidence has shown that the archaean Haloferax volcanii is naturally competent, which leads to the hypothesis that H.volcanii may use quorum sensing as a regulatory mechanism as well. In the domain Archaea, quorum sensing is a phenomenon that has received very little investigation and no concrete conclusions have been drawn yet.

Comparative genomics studies and nutritional competence growth studies with H. volcanii in conditioned media were performed to gain further insight into quorum sensing in archaea. Comparative proteomic studies suggest that a peptide autoinducer export protein may also function in archaea. The conditioned media growth studies suggest that an autoinducer susceptible to heat treatment may regulate competence in H. volcanii.