University of Iowa Honors Theses

Major Department

Microbiology

College

College of Liberal Arts & Sciences

Degree

BS (Bachelor of Science)

Session and Year of Graduation

Fall 2017

Honors Major Advisor

Linda McCarter

Thesis Mentor

Craig Ellermeier

Abstract

Bacillus subtilis is a soil dwelling organism which uses alternative extracytoplasmic function (ECF) sigma factors that respond to environmental stressors encountered by a cell. Upon encountering a signal, ECF sigma factors are activated and bind RNAP to initiate transcription of genes that confer resistance to stressors that threaten cellular integrity [5]. One such factor, sigmaV (sV), is required by B. subtilis for resistance to lysozyme. In the absence of lysozyme, sV is inhibited by the anti-sigma factor, RsiV, which is a transmembrane protein that has an extracellular lysozyme sensing domain. RsiV binds lysozyme, allowing for regulated intramembrane proteolysis (RIP) of the anti-sigma factor. The rate limiting step in degradation of RsiV is site-1 cleavage, which is performed by signal peptidase. Once RsiV is degraded it releases sV,allowing it to bind RNAP and transcribe lysozyme resistance genes. We sought to understand how RsiV avoids signal peptidase cleavage in the absence of lysozyme. To investigate this, we fused various lengths of RsiV to GFP in order to identify portions of RsiV needed to shield it from signal peptidase cleavage in the absence of lysozyme. We also defined the transmembrane domain of RsiV using the substituted cysteine accessibility method (SCAM). These experiments contribute to our investigation of a putative amphipathic helix with protective properties from signal peptidase.

Total Pages

11

Copyright

Copyright (c) 2017 Paige Kies

Included in

Cell Biology Commons

COinS
 

URL

https://ir.uiowa.edu/honors_theses/236