TY - JOUR
T1 - In Vitro Interaction of the Escherichia coli Cyclic AMP Receptor Protein with the Lactose Repressor
AU - Fried, Michael G.
AU - Daugherty, Margaret A.
PY - 2001/4/6
Y1 - 2001/4/6
N2 - Sedimentation equilibrium studies show that the Escherichia coli cyclic AMP receptor protein (CAP) and lactose repressor associate to form a 2:1 complex in vitro. This is, to our knowledge, the first demonstration of a direct interaction of these proteins in the absence of DNA. No 1:1 complex was detected over a wide range of CAP concentrations, suggesting that binding is highly cooperative. Complex formation is stimulated by cAMP, with a net uptake of 1 equivalent of cAMP per molecule of CAP bound. Substitution of the dimeric lacI-18 mutant repressor for tetrameric wild-type repressor completely eliminates detectable binding. We therefore propose that CAP binds the cleft between dimeric units in the repressor tetramer. CAP-lac repressor interactions may play important roles in regulatory events that take place at overlapping CAP and repressor binding sites in the lactose promoter.
AB - Sedimentation equilibrium studies show that the Escherichia coli cyclic AMP receptor protein (CAP) and lactose repressor associate to form a 2:1 complex in vitro. This is, to our knowledge, the first demonstration of a direct interaction of these proteins in the absence of DNA. No 1:1 complex was detected over a wide range of CAP concentrations, suggesting that binding is highly cooperative. Complex formation is stimulated by cAMP, with a net uptake of 1 equivalent of cAMP per molecule of CAP bound. Substitution of the dimeric lacI-18 mutant repressor for tetrameric wild-type repressor completely eliminates detectable binding. We therefore propose that CAP binds the cleft between dimeric units in the repressor tetramer. CAP-lac repressor interactions may play important roles in regulatory events that take place at overlapping CAP and repressor binding sites in the lactose promoter.
UR - http://www.scopus.com/inward/record.url?scp=0035815722&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0035815722&partnerID=8YFLogxK
U2 - 10.1074/jbc.M009087200
DO - 10.1074/jbc.M009087200
M3 - Article
C2 - 11152685
AN - SCOPUS:0035815722
SN - 0021-9258
VL - 276
SP - 11226
EP - 11229
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 14
ER -