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Publication Abstract from PubMed

The adult human gut presents a complicated ecosystem where host-bacterium symbiosis plays an important role. Bacteroides thetaiotaomicron is a predominant member of the gut microflora, providing the human digestive tract with a large number of glycolytic enzymes. Expression of many of these enzymes appears to be controlled by histidine kinase receptors that are fused into unusual hybrid two-component systems that share homologous periplasmic sensor domains. These sensor domains belong to the third most populated (HK3) family based on a previous bioinformatics analysis of predicted histidine kinase sensors. Here, we present crystal structures of two sensor domains representative of the HK3 family. Each sensor is folded into three domains: two seven-bladed beta-propeller domains and one beta-sandwich domain. Both sensors form dimers in crystals and one sensor appears to be physiologically relevant. The folding characteristics in the individual domains, the domain organization, and the oligomeric architecture are all unique to the HK3 sensors. The sequence analysis of the HK3 sensors indicates that these sensors are shared among other signaling molecules, implying a combinatorial molecular evolution. This article is protected by copyright. All rights reserved.

Crystal Structures of Apparent Saccharide Sensors from Histidine Kinase Receptors Prevalent in a Human Gut Symbiont.,Zhang Z, Liu Q, Hendrickson WA FEBS J. 2014 Jul 3. doi: 10.1111/febs.12904. PMID:24995510^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.