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LEV1 repressor

LEV1 is a coding gene encodes fusion protein LexA-VVD. VVD is a blue light sensor, a small light-oxygen-voltage (LOV) domain-containing protein from Neurospora crassa, and it is fused to the C-terminus of DNA-binding domain of LexA repressor of the Escherichia coli SOS regulon to form LEV1 fusion protein.

Usage and Biology

This fusion protein is a light repressor used in a single component light-repressed expression system. Upon blue light irradiation, a cysteine flavin adduct is formed in the VVD domain, causing conformational changes of the domain and the subsequent dimerization of the LEV1. The dimer would then bind its cognate operator sequence and repress the promoter activity. When in dark, the absence of dimer allows the proceeding of target gene expression. This fusion protein works with E. coli SOS promoter and associated operator sequence.

Lev1 is 714bp. Figure 2 shows a colony PCR amplifying DNA section harboring ColE promoter and LEV1 gene in pLEV1(408) vector.

Figure 2: The agarose gel electrophoresis of LEV1 colony PCR product

Reference

Chen, X., Liu, R., Ma, Z., Xu, X, Zhang, H., Xu, J. & Yang, 2016. An extraordinary stringent and sensitive light-switchable gene expression system for bacterial cells. Cell Research, 26 (7): 854-7.

Levskaya A, Chevalier AA, Tabor JJ, Simpson ZB, Lavery LA, et al. (2005) Synthetic biology: Engineering Escherichia coli to see light. Nature 438: 441–442.

Sequence and Features