Wf. Burkholder et al., MUTATIONS IN THE C-TERMINAL FRAGMENT OF DNAK AFFECTING PEPTIDE BINDING, Proceedings of the National Academy of Sciences of the United Statesof America, 93(20), 1996, pp. 10632-10637
Escherichia coli DnaK acts as a molecular chaperone through its ATP-re
gulated binding and release of polypeptide substrates. Overexpressing
a C-terminal fragment (CTF) of DnaK (Gly-384 to Lys-638) containing th
e polypeptide substrate binding domain is lethal in wild-type E. coli,
This dominant-negative phenotype may result from the nonproductive bi
nding of CTF to cellular polypeptide targets of DnaK, Mutations affect
ing DnaK substrate binding were identified by selecting noncytotoxic C
TF mutants followed by in vitro screening, The clustering of such muta
tions in the three-dimensional structure of CTF suggests the model tha
t loops L(1,2) and L(4,5) form a rigid core structure critical for int
eractions with substrate.