Designed Proteins as Novel Imaging Reagents in Living Escherichia coli

• Published in: Chembiochem : a European journal of chemical biology 2016-09, Vol.17 (17), p.1652-1657
• Main Authors: Pratt, Susan E., Speltz, Elizabeth B., Mochrie, Simon G. J., Regan, Lynne
• Format: Article
• Language: English
• Subjects: Bacterial Proteins - analysis; Bacterial Proteins - metabolism; Cytoskeletal Proteins - analysis; Cytoskeletal Proteins - metabolism; E coli; Escherichia coli; Escherichia coli - cytology; Escherichia coli - metabolism; fluorescence imaging; fluorescent probes; Luminescent Proteins - chemistry; Luminescent Proteins - genetics; Luminescent Proteins - metabolism; Microbial Viability; Peptides - chemistry; Peptides - genetics; Peptides - metabolism; protein design; Proteins; repeat protein; tag-probe system
• ISSN: 1439-4227; 1439-7633
• DOI: 10.1002/cbic.201600252

Fluorescence imaging is a powerful tool to study protein function in living cells. Here, we introduce a novel imaging strategy that is fully genetically encodable, does not require the use of exogenous substrates, and adds a minimally disruptive tag to the protein of interest (POI). Our method was based on a set of designed tetratricopeptide repeat affinity proteins (TRAPs) that specifically and reversibly interact with a short, extended peptide tag. We co‐expressed the TRAPs fused to fluorescent proteins (FPs) and the peptide tags fused to the POIs. We illustrated the method using the Escherichia coli protein FtsZ and showed that our system could track distinct FtsZ structures under both low and high expression conditions in live cells. We anticipate that our imaging strategy will be a useful tool for imaging the subcellular localization of many proteins, especially those recalcitrant to imaging by direct tagging with FPs. TRAPping E. coli: We introduced a no‐ vel in vivo imaging strategy based on a set of designed tetratricopeptide repeat affinity proteins (TRAPs) that specifically and reversibly interact with a short peptide tag. It is fully genetically encodable and requires no exogenous substrates. We demonstrate its utility by imaging the E. coli protein FtsZ.