ジャーナル: Nat Commun / 年: 2021 タイトル: Mechanism of NanR gene repression and allosteric induction of bacterial sialic acid metabolism. 著者: Christopher R Horne / Hariprasad Venugopal / Santosh Panjikar / David M Wood / Amy Henrickson / Emre Brookes / Rachel A North / James M Murphy / Rosmarie Friemann / Michael D W Griffin / ...著者: Christopher R Horne / Hariprasad Venugopal / Santosh Panjikar / David M Wood / Amy Henrickson / Emre Brookes / Rachel A North / James M Murphy / Rosmarie Friemann / Michael D W Griffin / Georg Ramm / Borries Demeler / Renwick C J Dobson / 要旨: Bacteria respond to environmental changes by inducing transcription of some genes and repressing others. Sialic acids, which coat human cell surfaces, are a nutrient source for pathogenic and ...Bacteria respond to environmental changes by inducing transcription of some genes and repressing others. Sialic acids, which coat human cell surfaces, are a nutrient source for pathogenic and commensal bacteria. The Escherichia coli GntR-type transcriptional repressor, NanR, regulates sialic acid metabolism, but the mechanism is unclear. Here, we demonstrate that three NanR dimers bind a (GGTATA)-repeat operator cooperatively and with high affinity. Single-particle cryo-electron microscopy structures reveal the DNA-binding domain is reorganized to engage DNA, while three dimers assemble in close proximity across the (GGTATA)-repeat operator. Such an interaction allows cooperative protein-protein interactions between NanR dimers via their N-terminal extensions. The effector, N-acetylneuraminate, binds NanR and attenuates the NanR-DNA interaction. The crystal structure of NanR in complex with N-acetylneuraminate reveals a domain rearrangement upon N-acetylneuraminate binding to lock NanR in a conformation that weakens DNA binding. Our data provide a molecular basis for the regulation of bacterial sialic acid metabolism.