POSTERS - BLAST X - University of Utah

BLAST X ______ Poster #8
NUTRIENT SENSING BY A HUMAN GUT SYMBIONT
Hongjun Zheng 1 , Susan Firbank 1 , Eric Martens 2 , Edith Diaz 1 , Rick Lewis 1 , Jeff Gordon 2 and
David Bolam 1
1. Institute for Cell and Molecular Biosciences, Newcastle University, The Medical School,
Framlington Place, Newcastle upon Tyne NE2 4HH, UK
2. Center for Genome Sciences, Washington University, St Louis, USA.
The gut microbiota play an important role in human health and nutrition. Bacteroides
thetaiotaomicron (Bt) is a dominant gut symbiont whose main sources of carbon and energy are
dietary and host polysaccharides, reflected in the presence on the genome of a large number of
genes involved in the sensing, acquisition and processing of complex carbohydrates. One of the
most striking features of the Bt genome are 33 genes encoding novel hybrid two component
systems (HTCS) that contain all of the domains of a classical TCS in a single polypeptide.
Custom Genechip arrays reveal that when Bt is grown in the presence of inulin, a β-1,2 linked
fructose storage polysaccharide, a specific locus composed of eight genes predicted to be
involved in polysaccharide binding, uptake and degradation is activated. The closest regulatory
protein to this locus is an HTCS, BT1754. Genetic, biochemical and structural studies reveal
that BT1754 is the sensor that controls fructan utilisation and the identity of the signalling
molecule itself, as well as the mechanism of signal perception and insights into signal
transduction across the cytoplasmic membrane.
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