Modulation of CO2 utilization by Cupriavidus necator H16 for high value chemical production

富营养化红藻的CO2同化是由Calvin-Benson-Bassham(CBB)循环介导的，该循环由两个几乎相同的CBB操纵子编码，一个位于PHG1巨质粒上，另一个位于2号染色体上(Pohlmann等，2006)。这些操纵子的有效表达，特别是编码主要限速酶1，5-二磷酸核酮糖羧酸酶/加氧酶(Rubisco)的基因，是至关重要的。这两个操纵子和受到位于CBB操纵子染色体拷贝5‘端的cbbR转录激活子的严格调控(Kusian和Bowien，1995)。这种LysR-型调控蛋白通过与CBB操纵子的相同启动子序列结合来控制CBB操纵子的表达(Dangle和Tabita，2015)。不依赖LysR，并且最好是CBB操纵子的结构性转录可能被证明有利于提高CBB循环的二氧化碳固定效率。为了进一步改善内源二氧化碳的同化途径，我们实现了编码功能性羧基体编码的合成DNA模块的可控表达，以实现CaS和Rubisco分子的共定位，从而提高了二氧化碳捕获能力。

CO2 assimilation in R. eutropha, is mediated by Calvin-Benson-Bassham (CBB) cycle encoded by two almost identical cbb operons, one located on the pHG1 megaplasmid and the other on chromosome 2 (Pohlmann et al., 2006). The effective expression of these operons, and in particular the genes encoding the major rate-limiting enzyme, ribulose 1,5-bisphosphate carboxylase/ oxygenase (RubisCO), are crucial. Both operons and are tightly regulated by the cbbR transcriptional activator located at the 5' end of the chromosomal copy of the cbb operon (Kusian and Bowien, 1995). This LysR-type regulatory protein con-trols the expression of the cbb operons by binding to their identical promoter sequences (Dangel and Tabita, 2015). LysR independent, and preferably constitutive transcription of the cbb operon might prove advantageous for enhancing the efficiency of CO2 fixation efficiency of the CBB cycle. To further improve the endogenous CO2 assimilation pathway we bring about the controllable expression of synthetic DNA modules encoding functional carboxysomes for the co-localisation of CAs and RuBisCO molecules with improved CO2-capture capabilities.