title: Phosphoprotein Crh-Ser46-P displays altered binding to CcpA to effect carbon catabolite regulation.
abstract: In Gram-positive bacteria, the catabolite control protein A (CcpA) functions as the master transcriptional regulator of carbon catabolite repression/regulation (CCR). To effect CCR, CcpA binds a phosphoprotein, either HPr-Ser46-P or Crh-Ser46-P. Although Crh and histidine-containing protein (HPr) are structurally homologous, CcpA binds Crh-Ser46-P more weakly than HPr-Ser46-P. Moreover, Crh can form domain-swapped dimers, which have been hypothesized to be functionally relevant in CCR. To understand the molecular mechanism of Crh-Ser46-P regulation of CCR, we determined the structure of a CcpA-(Crh-Ser46-P)-DNA complex. The structure reveals that Crh-Ser46-P does not bind CcpA as a dimer but rather interacts with CcpA as a monomer in a manner similar to that of HPr-Ser46-P. The reduced affinity of Crh-Ser46-P for CcpA as compared with that of HPr-Ser46 P is explained by weaker Crh-Ser46-P interactions in its contact region I to CcpA, which causes this region to shift away from CcpA. Nonetheless, the interface between CcpA and helix alpha 2 of the second contact region (contact region II) of Crh-Ser46-P is maintained. This latter finding demonstrates that this contact region is necessary and sufficient to throw the allosteric switch to activate cre binding by CcpA.
authors.affiliation: Department of Biochemistry & Molecular Biology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Schumacher
authors.forename: Gerald
authors.initials: G
authors.lastname: Seidel
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Hillen
authors.forename: Richard G
authors.initials: RG
authors.lastname: Brennan
mesh_terms: D000595:Amino Acid Sequence; D001410:Bacillus megaterium / Q000378:metabolism; D001412:Bacillus subtilis / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism*; D004269:DNA, Bacterial / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020218:Response Elements / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; C118042:Crh protein, Bacillus subtilis; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D010750:Phosphoproteins; D012097:Repressor Proteins; C069286:catabolite control proteins, bacteria; D002244:Carbon; C110847:HPr kinase; D017346:Protein Serine-Threonine Kinases