A high-throughput immobilized bead screen for stable proteins and multi-protein complexes

Area of Science:

• Molecular Biology
• Biochemistry
• Protein Expression

Background:

• Identifying bacterial clones that express soluble proteins and stable multiprotein complexes is crucial for various biological studies.
• Current methods for screening protein expression can be laborious and time-consuming.

Purpose of the Study:

• To develop and validate a novel in vitro colony screening method for identifying Escherichia coli expressing soluble proteins and stable, assembled multiprotein complexes.
• To streamline the process of clone selection and eliminate the need for replica plating.

Main Methods:

• Utilized a dual-tagging system (6His and GFP S11) for fluorescent labeling of proteins in E. coli.
• Developed a partial colony lysis and filtration method to capture soluble proteins and complexes on metal affinity beads.
• Analyzed fluorescence from colonies and captured proteins to assess total expression and solubility/stability.

Main Results:

• Successfully screened a DNA fragment library of human p85, identifying clones expressing desired domains.
• Effectively distinguished between stable and unstable multi-protein complexes, isolating intact heterotrimeric E. coli YheNML complexes.
• Demonstrated that the assay provides both total expression and solubility/stability information for clone selection.

Conclusions:

• The described in vitro colony screen is an efficient tool for selecting E. coli clones expressing soluble proteins and stable protein complexes.
• This method simplifies clone selection and propagation, offering a significant advantage over traditional techniques.
• The assay's ability to differentiate complex stability is valuable for studying protein-protein interactions and complex assembly.