title: Revisiting the mechanism of activation of cyclic AMP receptor protein (CRP) by cAMP in Escherichia coli: lessons from a subunit-crosslinked form of CRP.
abstract: Cyclic AMP receptor protein (CRP), the global transcription regulator in prokaryotes, is active only as a cAMP-CRP complex. Binding of cAMP changes the conformation of CRP, transforming it from a transcriptionally 'inactive' to an 'active' molecule. These conformers are also characterized by distinct biochemical properties including the ability to form an S-S crosslink between the C178 residues of its two monomeric subunits. We studied a CRP variant (CRP(cl)), in which the subunits are crosslinked. We demonstrate that CRP(cl) can activate transcription even in the absence of cAMP. Implications of these results for the crystallographically-determined structure of cAMP-CRP are discussed.
authors.affiliation: Department of Biochemistry, Bose Institute, P-1/12, C.I.T. Scheme VIIM, Kolkata 700054, India.
authors.forename: Abinit
authors.initials: A
authors.lastname: Saha
authors.affiliation: Department of Chemistry, Bose Institute, P-1/12, C.I.T. Scheme VIIM, Kolkata 700054, India.
authors.forename: Jayanta
authors.initials: J
authors.lastname: Mukhopadhyay
authors.affiliation: Department of Biochemistry, Bose Institute, P-1/12, C.I.T. Scheme VIIM, Kolkata 700054, India.
authors.forename: Ajit Bikram
authors.initials: AB
authors.lastname: Datta
authors.affiliation: Department of Biochemistry, Bose Institute, P-1/12, C.I.T. Scheme VIIM, Kolkata 700054, India. Electronic address: pradeep@jcbose.ac.in.
authors.forename: Pradeep
authors.initials: P
authors.lastname: Parrack
mesh_terms: D001665:Binding Sites; D018360:Crystallography, X-Ray; D000242:Cyclic AMP / Q000737:chemistry* / Q000235:genetics; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure; D004926:Escherichia coli; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure; D011485:Protein Binding; D011487:Protein Conformation; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D011953:Receptors, Cyclic AMP / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure; D013329:Structure-Activity Relationship; D015533:Transcriptional Activation / Q000235:genetics*
chemical_list: D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D021122:Protein Subunits; D011953:Receptors, Cyclic AMP; C047947:cyclic AMP receptor protein, E coli; D000242:Cyclic AMP
keywords: Activation by cAMP; Crosslinked CRP; Transcription activation