Distinct chaperone affinity to folding variants of homologous recombinant proteins

Two beta-galactosidase fusion proteins, VP1LAC and LACVP1, contain the same viral capsid protein fused to either the amino or carboxy termini of the enzyme, respectively. Once produced in Escherichia coli, these fusions undergo a rapid, site-limited proteolysis releasing active beta-galactosidase fragments indistinguishable from the native enzyme. In vivo binding preferences of DnaK and GroEL chaperones for these homologous protein fragments have been observed, indicating that accessibility of chaperone target sites in degradation products could be determined by the folding pathway undergone by the larger polypeptide before the proteolytic attack.