The structure of CodY, a GTP- and isoleucine-responsive regulator of stationary phase and virulence in gram-positive bacteria.
CodY is a global regulator of transcription in gram-positive bacteria. It represses during growth genes required for adaptation to nutrient limitation, including virulence genes in some human pathogens. CodY activity is regulated by GTP and branched chain amino acids, metabolites whose intracellular concentrations drop as cells enter stationary phase. Although CodY has a highly conserved sequence, it has no significant similarity to proteins of known structure. Here we report crystal structures of two fragments of CodY from Bacillus subtilis that clearly constitute its cofactor and DNA binding domains and reveal that CodY is a chimera of previously observed folding units. The N-terminal cofactor-binding fragment adopts a fold reminiscent of the GAF domains found in cyclic nucleotide phosphodiesterases and adenylate cyclases. It is a dimer stabilized by an intermolecular six alpha-helical bundle that buries an extensive apolar surface rich in residues invariant in CodY orthologues. The branched chain amino acid ligands reside in hydrophobic pockets of each monomer distal to the dimer-forming surface. The structure of the C-terminal DNA binding domain belongs to the winged helix-turn-helix family. The implications of the structure for DNA binding by CodY and its control by cofactor binding are discussed.
Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5YW, United Kingdom.
Vladimir M
VM
Levdikov
Elena
E
Blagova
Pascale
P
Joseph
Abraham L
AL
Sonenshein
Anthony J
AJ
Wilkinson
D000262:Adenylyl Cyclases / Q000737:chemistry; D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism / Q000502:physiology*; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D019281:Dimerization; D015964:Gene Expression Regulation, Bacterial; D006094:Gram-Positive Bacteria / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000737:chemistry*; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D050436:Regulatory Elements, Transcriptional; D012097:Repressor Proteins / Q000378:metabolism / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D014774:Virulence
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D008024:Ligands; D012097:Repressor Proteins; D006160:Guanosine Triphosphate; D004247:DNA; D000262:Adenylyl Cyclases