We present a methodolog
y for targe
ting quantum dots to specific proteins on living cells in two steps. In the first step,
Escherichia coli lipoic acid ligase (LplA) site-specificall
y attaches 10-bromodecanoic acid onto a 13 amino acid recognition sequence that is geneticall
y fused to a protein of interest. In the second step, quantum dots derivatized with HaloTag, a modified haloalkane dehalogenase, react with the ligated bromodecanoic acid to form a covalent adduct. We found this targe
ting method to be specific, fast, and full
y orthogonal to a previousl
y reported and analogous quantum dot targe
ting method using
E. coli biotin ligase and streptavidin. We used these two methods in combination for two-color quantum dot visualization of different proteins expressed on the same cell or on neighboring cells. Both methods were also used to track single molecules of neurexin, a s
ynaptic adhesion protein, to measure its lateral diffusion in the presence of neuroligin, its trans-s
ynaptic adhesion partner.
Keywords:
ting&qsSearchArea=searchText">quantum dot targeting; y&qsSearchArea=searchText">fluorescence microscopy; single-molecule imaging; lipoic acid ligase; HaloTag