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Structure of full length unliganded CodY from Bacillus subtilisStructure of full length unliganded CodY from Bacillus subtilis
Structural highlights
FunctionCODY_BACSU DNA-binding protein that represses the expression of many genes that are induced as cells make the transition from rapid exponential growth to stationary phase and sporulation. It is a GTP-binding protein that senses the intracellular GTP concentration as an indicator of nutritional limitations. At low GTP concentration it no longer binds GTP and stop to act as a transcriptional repressor.[1] [2] Publication Abstract from PubMedCodY is a branched-chain amino acid (BCAA) and GTP sensor, and a global regulator of transcription in low G + C Gram-positive bacteria. It controls the expression of over 100 genes and operons, principally by repressing during growth genes whose products are required for adaptations to nutrient limitation. CodY consists of a GAF domain that binds BCAAs and a winged helix-turn-helix (wHTH) domain that binds to DNA, but the way in which these domains interact and the structural basis of the BCAA-dependence of this interaction are unknown. To gain new insights, we determined the crystal structure of unliganded CodY from Bacillus subtilis revealing a 10-turn alpha-helix linking otherwise discrete GAF and wHTH domains. The structure of CodY in complex with isoleucine revealed a reorganised GAF domain. In both complexes CodY was tetrameric. Size exclusion chromatography with multiangle laser light scattering (SEC-MALLS) experiments showed that CodY is a dimer at concentrations found in bacterial cells. Comparison of structures of dimers of unliganded CodY and CodY-Ile derived from the tetramers showed a splaying of the wHTH domains when Ile was bound; splaying is likely to account for the increased affinity of Ile-bound CodY for DNA. Electrophoretic mobility shift and SEC-MALLS analyses of CodY binding to 19-36 base-pair operator fragment are consistent with isoleucine-dependent binding of two CodY dimers per duplex. The implications of these observations for effector control of CodY activity are discussed. Structure of the Branched Chain Amino Acid and GTP Sensing Global Regulator, CodY, from Bacillus subtilis.,Levdikov VM, Blagova EV, Young VL, Belitsky BR, Lebedev A, Sonenshein AL, Wilkinson AJ J Biol Chem. 2016 Dec 23. pii: jbc.M116.754309. doi: 10.1074/jbc.M116.754309. PMID:28011634[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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