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Studies on the transcriptional repressor LsrR and its potential interaction with DHAP

By Emily Gale

Abstract

Both Gram-positive and Gram-negative bacteria use cell-to-cell communication to regulate a variety of multicellular functions such as bioluminescence, biofilm formation, and virulence. This process, termed quorum-sensing, requires the synthesis and recognition ofhormone-like molecules called autoinducers. A particular autoinducer, autoinducer 2 (AI-2), is synthesized and recognized by many species of bacteria. This study focuses on the binding properties of the protein LsrR: a transcriptional repressor of the lsr operon, which is regulated by AI-2. Previous research has suggested that dihydroxyacetone phosphate (DHAP), a key metabolite, interacts directly with LsrR to repress transcription of the lsr operon. Here I report an optimized purification protocol for an N-terminal truncated version of LsrR (C-LsrR), attempt to crystallize C-LsrR, and begin to develop protocols to assess potential binding between C-LsrR and DHAP. Our initial approach of using intrinsic tyrosine fluorescence to quantify binding based on the protein's conformational changes was more difficult than expected. We then used a DHAP Assay Kit to measure unbound DHAP in solution before and after exposure to C-LsrR. Both methods seemed promising but need improvement before they will yield conclusive results

Year: 2016
OAI identifier: oai:triceratops.brynmawr.edu:10066/18564
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