Document Type

Honors Thesis

Publication Date

Winter 12-2019

Abstract

Group B Streptococcal (GBS) infections pose a great threat to mortality in neonates. Neonates are often exposed to GBS both before, during, and after delivery, which can cause a range of health problems including meningitis, sepsis, or stillbirth. One of the major virulence factors that contributes to the infectivity of the pathogen is the bacterial capsule. The capsule is a polysaccharide matrix surrounding the cell which helps in the evasion of host defenses, and penetration into normally sterile sites like the bloodstream. The highly conserved GBS protein CpsA has been shown to regulate expression of the capsule. The objective of this study is to explore protein-protein interactions with CpsA, as well as truncated versions of CpsA, using co-immunoprecipitation protocols to identify CpsA binding partners. Modified CpsA strains with a maltose binding protein (MBP) tag allow for specific selection of target protein using antibodies to that tag. Research has previously shown that deletion of the LytR domain, one of two extracellular domains that follows three membrane-spanning domains on the N-terminus, has a negative impact on capsule production, indicating an extracellular binding occurrence in this domain. Further evidence shows that a portion of the extracellular domain potentially binds at the septum of the cell, however the specifics of this interaction remain unknown. Therefore, extracellular interactions may be playing a role in capsule production and attachment to the cell wall. By demonstrating an interaction with other proteins, further targets could be identified for treatment of GBS infection.

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