Characterization of the CRPCY core formed after treatment with carboxypeptidase Y.
CRP is resistant to attack by carboxypeptidase Y at 37 degrees C, whereas cAMP-CRP is digested yielding a core terminating at Thr-202 and lacking the seven carboxyl-terminal amino acid residues. A similar core (CRPCY) is formed when CRP is incubated with carboxypeptidase Y at 47 degrees C in the absence of cAMP. CRPCY has a more open conformation than CRP at 37 degrees C. While unliganded CRP is resistant to trypsin, CRPCY is sensitive to tryptic attack. Dithionitrobenzoic acid-mediated intersubunit disulfide crosslinking of CRP requires cAMP, CRPCY subunits are crosslinked in the absence of cAMP. The carboxyl-terminal region of unliganded CRP is conformationally restricted at 37 degrees C. The CRPCY retains cAMP binding activity. The CRPCY which terminates at Thr-202, no longer binds lac P+ DNA nor stimulates abortive initiation by RNA polymerase from the lac P+ promoter. The results indicate that the C-terminal region of CRP participates in the conformational stability of the closed form of CRP and indirectly in DNA binding by the open cAMP-CRP conformer.
Yang
Z H
ZH
Department of Biological Sciences, Hunter College of CUNY, NY 10021.
Bobin
S
S
Krakow
J S
JS
D002268:Carboxypeptidases / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D002373:Cyclic AMP Receptor Protein / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D004247:DNA / Q000378:metabolism; D004220:Disulfides / Q000378:metabolism; D004228:Dithionitrobenzoic Acid / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D007700:Kinetics; D046911:Macromolecular Substances; D011487:Protein Conformation; D013696:Temperature; D014357:Trypsin / Q000378:metabolism
D002373:Cyclic AMP Receptor Protein; D004220:Disulfides; D046911:Macromolecular Substances; D004247:DNA; D004228:Dithionitrobenzoic Acid; D000242:Cyclic AMP; D002268:Carboxypeptidases; C022633:serine carboxypeptidase; D014357:Trypsin