Part:BBa_K2350022

Part description: Zeaxanthin belongs to carotenoid family and is widely found in the nature. It is also a natural color making corns, carrots and marigolds yellow. Moreover, zeaxanthin is an essential nutrient substance to human’s eyes, and some healthy supplements are made of it. Most of green plants produce zeaxanthin as an intermediate in carotenoid pathway. However, some cyanobacteria lack some genes and cannot produce zeaxanthin, such as Synechococcus elongatus PCC 7942. PCC7942 lacks only one gene making zeaxanthin, that is beta-carotene hydroxylase (CrtZ). To make Synechococcus elongatus PCC 7942 produce zeaxanthin, we construct a plasmid BBa_K2320022 under the control of PrbcL. After the expression of CrtZ, PCC 7942 can then be yellow.

Details: 1. We studied Professor Chuan-Hsiung Chang’s paper(Energy Environ. Sci., 2012, 5, 8318: Enhancing CO2 bio-mitigation by genetic engineering of cyanobacteria) and decided to construct pigment plasmid with the same promotor. The natural ribosome binding site is also referred to it. 2. The intrinsic promoter of Rubisco large subunit (PrbcL) can overexpress foreign genes in the cyanobacteria. Many plants’ protens in photosynthesis are under regulation of PrbcL. And the high activity to express foreign genes has been provrn. 3. CrtZ from Pantoea ananatis is a coding sequence of igem released part (BBa_I742158). It can lead to zeaxanthin and astaxanthin. However, the wild type Synechococcus elongatus PCC 7942 lacks of it and cannot make zeaxanthin naturally.