Straightforward MALDI-TOF MS based screening approach for selection of recombinant protein-expressing E. coli

Recombinant protein production is a milestone of modern biotechnology, drug development and scientific research. When obtaining recombinant protein producers, differences in expression levels among clones necessitate screening. Traditional widely used methods include protein electrophoresis and western blot hybridization. This protocol provides high-throughput advantages by eliminating time-consuming steps inherent to traditional methods, such as cell lysis, protein extraction, purification, antibody-based detection, and gel-based analysis. MALDI-TOF MS represents a simple, rapid and cost-effective method for bacterial species identification through protein fingerprint signature in clinical diagnostics, but not practically integrated into biotechnological workflow. This study proposes a fast and easy method for screening E. coli clones producing recombinant proteins with MALDI-TOF MS. The proposed method demonstrated efficiency in screening of E. coli producing several recombinant proteins with different properties: sfGFP; bacterial DNA binding proteins IHFα, IHFβ, HU; bacteriophage protein GP46 and camelid VHH antibody fragments.