Difference between revisions of "Part:BBa K1031410"
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When tested with 78 aromatic compounds, ON/OFF test via microplate reader showed that HcaR worked as a specific sensor to PPA (Fig 3). | When tested with 78 aromatic compounds, ON/OFF test via microplate reader showed that HcaR worked as a specific sensor to PPA (Fig 3). | ||
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Revision as of 05:20, 24 September 2013
HcaR-Terminator
HcaR-TT
Introduction
HcaR is a 32,838 Da (296 amino acids) protein, which belongs to LysR family. Its’ N-terminal domain functions in DNA binding via a helix-turn-helix motif, while C-terminal domain functions in multimerization. As an activator, HcaR activates the expression of hca cluster when exposed to ligands. It detects limited range of ligands, including 3-phenylpropionic acid (PPA) and cinnamic acid (CnA) [1]. Another gene cluster mhp locates downstream hca cluster. hca and mhp clusters are involved in the catabolism of PPA and CnA in E. coli (Fig. 1). The enzymes encoded by hca cluster degrade PPA and CnA to 2,3-DHPPA and 2,3-DHCnA respectively, which serve as the substrates of the mhp cluster. The enzymes in mhp cluster function in the cleavage of aromatic ring.
Compared with the sole 2,3-DHPPA, the special induction effect of PPA and 2,3-DHPPA is obtained, although PPA don’t behave as ligand alone. Based on the result and the observation of different binding site of PPA with MhpR, it is deduced that PPA and 2,3-DHPPA have synergistic effect to the activation of MhpR expression [3]. (That is to say, PPA enhances the activation effect as a cooperator of 2,3-DHPPA instead of a ligand.) The same effect is observed in 3-HPPA along with PPA.
Sequence and Features
- 10COMPATIBLE WITH RFC[10]
- 12COMPATIBLE WITH RFC[12]
- 21COMPATIBLE WITH RFC[21]
- 23COMPATIBLE WITH RFC[23]
- 25INCOMPATIBLE WITH RFC[25]Illegal NgoMIV site found at 849
Illegal AgeI site found at 522 - 1000COMPATIBLE WITH RFC[1000]
Our work
Ph/HcaR biosensor circuit is constructed. The coding sequence of HcaR was obtained from the genome of E. coli K12 via PCR. A Pc library of constitutive promoters are constructed to fine-tune the biosensor, which consists of Pc promoters at different intensity, including BBa_J23113, J23109, J23114 and J23106 (Fig 2). When tested with 78 aromatic compounds, ON/OFF test via microplate reader showed that HcaR worked as a specific sensor to PPA (Fig 3).