Part:BBa_K1399007

GFP (mut3b) with NYADAS-ssrA degradation tag

GFP (mut3b) (see part BBa_E0040) with added engineered NYADAS-ssrA degradation tag (see part BBa_M0050). The tag increases GFP turn-over rate, thus providing better temporal resolution of green fluorescence. In the same time, maximal fluorescence amplitudes will be lower as newly formed protein is degraded as soon as it is formed. SsrA tags encode peptide sequence that and is recognized by ClpA and ClpX unfoldases and ClpX mediator SspB.[1] ClpA and ClpX then form a proteosome-like complex with ClpP protease and the protein is degraded.[1] The final three residues of the tag determines the strength of interaction with ClpX and thus the final protein degradation rate.[2] The NYADAS tag encodes peptide sequence AANDENYNYDAS is reported to have low affinity to ClpX thus its mediated degradation very much depends on the concentration of SspB (ClpX mediator).[1] The two additional residues ‘NY’ extends tag between SspB and ClpX binding sites, thus preventing clash when both proteins are bound to the tag.[3] However, be aware that exact protein degradation rate is influenced by multiple other factors: ClpXP and ClpAP protease concentrations, protein stability, Km of binding to the protease, temperature [4].

References

[1] Flynn, J. M. et al. Overlapping recognition determinants within the ssrA degradation tag allow modulation of proteolysis. Proc. Natl. Acad. Sci. U. S. A. 98, 10584–9 (2001). [2] Andersen, J. B. et al. New unstable variants of green fluorescent protein for studies of transient gene expression in bacteria. Appl. Environ. Microbiol. 64, 2240–6 (1998). [3] McGinness, K. E., Baker, T. a & Sauer, R. T. Engineering controllable protein degradation. Mol. Cell 22, 701–7 (2006). [4] Purcell, O., Grierson, C. S., Bernardo, M. Di & Savery, N. J. Temperature dependence of ssrA-tag mediated protein degradation. J. Biol. Eng. 6, 10 (2012).