Synthetic Biology Parts, Devices and Applications

11.4 Conclusions 227

11.4 Conclusions

Literature suggests an astonishing versatility in peptide functionalities (Table 11.1).
Now standard directed evolution and selection techniques have the potential to
amplify this spectrum. Indeed, successful peptide engineering by directed evolu-
tion has already been achieved as exemplified by the identification of novel
chromophore‐binding peptides or peptide mimotopes from phage libraries.
Still, the exploitation of the full potential of functional peptides for the engi-
neering of synthetic chimeras seems to be limited by the available knowledge on
permissive sites and the need for relatively labor‐intensive methods to identify
them in a scaffold of interest. Therefore more comprehensive rational methods
would be desirable that, together with recent advances in DNA modification
methods on chromosome‐level [123–125], might be a step toward the exploita-
tion of the full potential of superfunctionalized proteins.

(Continued )

Table 11.1 Available functional peptide tags.

Ta g

Function

substrate/enzyme

Length

(aa’s) Application References

Peptide binds small molecule

Tetracysteine

tag (TC‐tag)

FlAsH, ReAsH 6 Intracellular fluorescent labeling

of proteins in vivo and in vitro,

eukaryotic cells, and bacteria

[33]

6xHis‐tag Ni‐NTA

derivatives,

HisZiFit

6 Extracellular labeling of proteins [39, 40]

Texas Red

aptamer

Texas Red and

derivatives

38 Intracellular calcium sensing [41]

Lanthanide

binding tag

Lanthanides 15–20 Extracellular labeling and in vitro

structural studies by NMR or X‐

ray crystallography

[43]

Peptide acts as recognition site for labeling proteins

Biotin

acceptor

peptide (BAP)

Biotin

derivatives/biotin

ligase

22 Extra‐ and intercellular labeling

of proteins in vivo and

eukaryotic cells

[63]

Lipoic acid

acceptor

peptide

(LAP1 and

LAP2)

Lipoic acid

derivatives,

coumarin

derivatives/lipoic

acid ligase

13–22 Extra‐ and intracellular labeling

of proteins in vivo and

eukaryotic cells

[53, 54]

Peptide is recognized by hydrolyzing enzyme

TEV protease

recognition

peptide

TEV protease 7 Cleavage of fusion proteins; has

been explored as tool for

mediated posttranslational

modification in systems biology

[75]