PROBING THE FUNCTIONAL ROLE OF DIFFERENT REGIONS OF THE OsmY PROTEIN

• Main Author: (NIM:20517022), RENDY
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/30317
• Institution: Institut Teknologi Bandung

Escherichia coli can adapt to various stress conditions in order to grow and <br /> <br /> survive, one of which is hyperosmotic stress. In overcoming hyperosmotic stress, <br /> <br /> E. coli and other bacteria usually activate several genes under the control of <br /> <br /> common regulator proteins. The accumulation of regulatory proteins and gene <br /> <br /> transcriptions allows E. coli to provide resistance against stress. The osmotically <br /> <br /> inducible protein Y (OsmY) is a 20 kDa periplasmic protein (with a yet unknown <br /> <br /> function) is one such protein whose expression level increases up to 10-fold under <br /> <br /> hyperosmotic stress. OsmY is highly expressed in the stationary phase natively <br /> <br /> and under hyperosmotic shock conditions. It is believed that OsmY keeps the <br /> <br /> cytoplasmic membrane from shrinking by contacting the phospholipid interfaces <br /> <br /> surrounding the periplasmic space and likely assists in survival under <br /> <br /> hyperosmotic stress. Although the structure of OsmY is unknown, predictive <br /> <br /> modelling studies suggest a presence of a disordered N-terminal region and two <br /> <br /> membrane-binding bacterial OsmY and Nodulation (BON) domains separated by <br /> <br /> a 10 amino acid linker. The presence of BON domains in OsmY suggests that <br /> <br /> these domains may link the inner and outer membrane. Existing studies in the lab <br /> <br /> show that overexpression of OsmY helps growth in hyperosmotic environments. <br /> <br /> In this research, different structural regions in OsmY were probed to ascertain if <br /> <br /> they contribute to the function of OsmY. We systematically generated three <br /> <br /> truncation variants of OsmY wherein the N-terminus, a BON domain, and the <br /> <br /> linker were truncated respectively. Two additional variants were created wherein <br /> <br /> the linker between the BON domains were duplicated and triplicated. We observe <br /> <br /> that the removal of one of the BON domains severely impairs the ability of E. coli <br /> <br /> to survive at hyperosmotic stress. <br />