Date of Award

Spring 5-2017

Degree Type

Honors College Thesis



First Advisor

Mohamed Elasri

Advisor Department

Biological Sciences


There are many transcriptional regulators found in pathogenic Staphylococcus aureus. Many of these regulators are essential for the organism’s ability to switch from commensal form to the virulent pathogenic form. One of these main regulators is CodY. This regulator has been shown to be responsive to nutrient availability during phases of growth. Additionally, we have recently found that MsaB, the only protein coding ORF of the msaABCR operon, is a putative co-regulator of capsule along with CodY. To explore these regulator interactions, we produced mutations of codY and msaABCR individually and a double mutation of msaABCR/ codY. We have observed that both MsaB and CodY bind to the cap promoter region in very close proximity. CodY binds to this region in early phases of growth in response to nutrients as a repressor of cap transcription and MsaB binds to this region in the later phase of growth as an activator of cap transcription. Using a chemically defined medium (CDM), we have shown that the msaABCR operon and ultimately MsaB is also likely involved in sensing nutrient availability. In this study, we show that the transcriptional regulator, MsaB, interacts with another known DNA binding transcriptional regulator, CodY, in S. aureus. These interactions are important in the regulation of sensing environmental nutrients and regulating capsule production in S. aureus.