Part:BBa_K1031100

CapR-Terminator

Characterization

Instruction

CapR is a transcriptional activator which belongs to NtrC family as DmpR. Sequence analysis of both capR gene and CapR protein reveals the significant similarity with DmpR, for their protein sequences are distinct at 9 residues only.

Structure

CapR has four domains. A domain is the signal reception domain, which undergoes conformational change when exposed to proper inducers. B domain is a linker, regulating the relative spatial position of A domain and C domain. C domain is the transcriptional activation domain. D domain contains a helix-turn-helix motif, which is capable of binding DNA sequence on Po promoter.(Fig 1)

Fig 1 Structure of CapR protein. From N terminal to C terminal are domain A, domain B, domain C, domain D.

Detection profile

CapR detects phenol and its’ derivatives such as catechol. The detection profile of CapR is widely overlapped with that of DmpR. Previous works showed that when exposed to inducers at the concentration of 100µM, CapR's response to phenol and catechol could reach 300 and 100 fold respectively via firefly luciferin assay.

Sequence and Features

Assembly Compatibility:

10
COMPATIBLE WITH RFC[10]
12
COMPATIBLE WITH RFC[12]
21
INCOMPATIBLE WITH RFC[21]
Illegal BglII site found at 86
23
COMPATIBLE WITH RFC[23]
25
INCOMPATIBLE WITH RFC[25]
Illegal NgoMIV site found at 283
Illegal NgoMIV site found at 564
1000
INCOMPATIBLE WITH RFC[1000]
Illegal BsaI.rc site found at 790
Illegal SapI.rc site found at 1447

Construction of biosensor circuit

Po/CapR biosensor circuit is constructed. The coding sequence of CapR was synthesized. A Pc library of constitutive promoters are constructed to fine-tune the biosensor, which consists of Pc promoters BBa_J23113 and BBa_J23109 (Fig 2).

Fig 2 Schematic diagram of biosensor circuit Po/CapR. The orange arrowheads represent promoters. Green ovals stand for RBS(Ribosome Binding Site). Terminators B0015 are shown in red squares.