Enzymic characterization of a novel member of the regulatory B-like carboxypeptidase with transcriptional repression function: stimulation of enzymic activity by its target DNA.
The adipocyte-enhancer binding protein (AEBP) 1 is a novel transcriptional repressor with carboxypeptidase (CP) activity. AEBP1 binds to a regulatory sequence (termed adipocyte enhancer 1, AE-1) located in the proximal promoter region of the adipose P2 (aP2) gene, which encodes the adipocyte fatty-acid binding protein. Sequence comparisons and kinetic studies using known carboxypeptidase substrates, activators and inhibitors have characterized AEBP1 as a member of the regulatory B-like CP family. Significantly, the inherent CP activity of AEBP1 is stimulated by the AE-1 sequence. Our results indicate that AEBP1 is activated by a novel mechanism, wherby the direct binding of DNA enhances its protease activity. These results represent the first demonstration of DNA-mediated regulation of CP activity.
Muise
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Department of Biochemistry, Faculty of Medicine, Sir Charles Tupper Medical Building, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4H7.
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D001665:Binding Sites; D043424:Carboxypeptidase B; D002268:Carboxypeptidases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020134:Catalytic Domain; D004247:DNA / Q000378:metabolism* / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism; D004742:Enhancer Elements, Genetic / Q000235:genetics; D004789:Enzyme Activation / Q000187:drug effects; D020128:Inhibitory Concentration 50; D036341:Intercellular Signaling Peptides and Proteins; D007700:Kinetics; D008565:Membrane Proteins / Q000819:agonists* / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D012097:Repressor Proteins / Q000819:agonists* / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013379:Substrate Specificity; D015032:Zinc / Q000378:metabolism
D004268:DNA-Binding Proteins; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D004247:DNA; D002268:Carboxypeptidases; D043424:Carboxypeptidase B; D015032:Zinc