Crystal structure of an activated form of the PTS regulation domain from the LicT transcriptional antiterminator.
The transcriptional antiterminator protein LicT regulates the expression of Bacillus subtilis operons involved in beta-glucoside metabolism. It belongs to a newly characterized family of bacterial regulators whose activity is controlled by the phosphoenolpyruvate:sugar phosphotransferase system (PTS). LicT contains an N-terminal RNA-binding domain (56 residues), and a PTS regulation domain (PRD, 221 residues) that is phosphorylated on conserved histidines in response to substrate availability. Replacement of both His207 and His269 with a negatively charged residue (aspartic acid) led to a highly active LicT variant that no longer responds to either induction or catabolite repression signals from the PTS. In contrast to wild type, the activated mutant form of the LicT regulatory domain crystallized easily and provided the first structure of a PRD, determined at 1.55 A resolution. The structure is a homodimer, each monomer containing two analogous alpha-helical domains. The phosphorylation sites are totally buried at the dimer interface and hence inaccessible to phosphorylating partners. The structure suggests important tertiary and quaternary rearrangements upon LicT activation, which could be communicated from the protein C-terminal end up to the RNA-binding domain.
van Tilbeurgh
H
H
Architecture et Fonction des Macromolécules Biologiques, UMR 6098 du CNRS, Université d'Aix-Marseille, I et II, ESIL-GBMA, 163 Avenue de Luminy Case 925, 13288 Marseille Cedex 9, France. vantil@esil.univ-mrs.fr
Le Coq
D
D
Declerck
N
N
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001412:Bacillus subtilis / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D019281:Dimerization; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; C098955:LicT protein, Bacteria; D014157:Transcription Factors