Protein Expression via the Molecular Chaperone ClpL

Abstract

Protein expression using bacterial systems has advanced substantially over the past few decades, but Escherichia coli is still the most commonly utilized expression host, despite issues related to protein solubility. Several solutions, such as different host strains, different vectors, and incubation with co-chaperones, have been developed to minimize protein aggregation and ensure high-quality protein production. Here, we review commonly used methods to increase protein solubility, with a focus on the Clp/Hsp100 family and pneumococcal ClpL, a novel member of the Clp/Hsp100 family that is highly induced in Streptococcus pneumoniae during heat shock. Unlike the DnaK system, which requires an additional co-chaperone system to reinstate the natural conformation of denatured target proteins, pneumococcal ClpL is able to disaggregate denatured proteins independently, without requiring a co-chaperone system. Accordingly, ClpL could be a useful chaperone system to solubilize foreign proteins during protein overexpression.