non-natural reporter proteins

After the pioneering works of Schultz's group and Chamberlin's group in 1989, bio-synthetic incorporation of non-natural amino-acids into proteins has been largely explored in chemical biology. Thanks to the engineering of new tRNAs able to carry 'new' amino-acids, combined with codon extension to the 4th base, we have now the ability to expand the chemical functionality of proteins. Indeed, we can introduce new chemical moieties into the protein backbone, and since it's a DNA based approach, it's heritable. This new variety of proteins opens several avenues for synthetic biology. Here, I spotlight two new non-natural reporter proteins.

a reporter for infrared spectroscopy
The non-natural amino-acid p-azido-l-phenylalanine (azF) vibrates in a window which is free from other protein vibration, therefore, this feature has been used to design a new infrared protein probe which incorporates azF into a G-coupled Protein Receptor (Rhodopsin). This allows to study GPCR's conformational changes by Fourier-transform infrared (FTIR) analysis. Upon the receptor activation, early conformational changes were observed that were not visible with classic techniques.
---/ citation /--- --- ---
Ye, S., Zaitseva, E., Caltabiano, G., Schertler, G., Sakmar, T., Deupi, X., & Vogel, R. (2010). Tracking G-protein-coupled receptor activation using genetically encoded infrared probes Nature, 464 (7293), 1386-1389 DOI: 10.1038/nature08948

non-natural red bioluminescence
The non-natural amino-acid 4-methoxy-phenylalanine has been incorporated into the position F82 of the reporter aequorin, resulting in a significant (44 nm) red-shift of the aequorin bioluminescence.
---/ citation /--- --- ---
Rowe, L., Ensor, M., Mehl, R., & Daunert, S. (2010). Modulating the Bioluminescence Emission of Photoproteins by Site-Directed Incorporation of Non-Natural Amino Acids
ACS Chemical Biology DOI: 10.1021/cb9002909