Poster Presentation The 43rd Lorne Conference on Protein Structure and Function 2018

Bacterial sialic acid regulation (#137)

Christopher R Horne 1 , Renwick CJ Dobson 1 2
  1. University of Canterbury, Christchurch, CANTERBURY, New Zealand
  2. Bio21 Institute, University of Melbourne, Melbourne, VICTORIA, Australia

Sialic acids are one of the most important amino sugars in biology. Found at the terminal end of glycan molecules, these negatively charged sugars act as receptors for cellular communication. Sialic acids also serve as a carbon, nitrogen, and energy source for bacterial pathogens that degrade it into fructose-6-phosphate, which can subsequently enter central metabolism. The canonical pathway that breaks down sialic acid following its import into the cell includes a lyase, kinase, epimerase, deacetylase, and a deaminase. This pathway is regulated in bacteria by the nanRepressor, however detailed structural evidence explaining this process is lacking. The nanRepressor from Escherichia coli has been experimentally shown to regulate the nanCMS and yjhBC operons, in addition to the canonical degradation pathway by binding to two or three tandem base pair repeats of the DNA sequence GGTATA. Collectively, the nan genes that are directly controlled by the nanRepressor are designated as being part of the ‘Sialoregulon’. While the biological role of the nanCMS operon is currently being studied, the biological role of the yjhBC operon has yet to be established. The primary function of this operon is believed to collectively provide the ability to convert and utilise less common derivatives of sialic acid to N-acetylneuraminic acid; the preferred substrate for the lyase in the degradation pathway. Our overall aim is to develop the first detailed ‘picture’ of how the nanRepressor regulates gene expression and elucidate the biological role of the enzymes in the wider pathway.