Molecular Microbial Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, the Netherlands.
Freshwater and Marine Ecology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, the Netherlands.
Metab Eng. 2019 Mar;52:68-76. doi: 10.1016/j.ymben.2018.11.002. Epub 2018 Nov 14.
To fill the "green absorption gap", a green absorbing proteorhodopsin was expressed in a PSI-deletion strain (ΔPSI) of Synechocystis sp. PCC6803. Growth-rate measurements, competition experiments and physiological characterization of the proteorhodopsin-expressing strains, relative to the ΔPSI control strain, allow us to conclude that proteorhodopsin can enhance the rate of photoheterotrophic growth of ΔPSI Synechocystis strain. The physiological characterization included measurement of the amount of residual glucose in the spent medium and analysis of oxygen uptake- and production rates. To explore the use of solar radiation beyond the PAR region, a red-shifted variant Proteorhodopsin-D212N/F234S was expressed in a retinal-deficient PSI-deletion strain (ΔPSI/ΔSynACO). Via exogenous addition of retinal analogue an infrared absorbing pigment (maximally at 740 nm) was reconstituted in vivo. However, upon illumination with 746 nm light, it did not significantly stimulate the growth (rate) of this mutant. The inability of the proteorhodopsin-expressing ΔPSI strain to grow photoautotrophically is most likely due to a kinetic rather than a thermodynamic limitation of its NADPH-dehydrogenase in NADP-reduction.
为了填补“绿色吸收差距”，在聚光叶绿素 a 蛋白缺失的集胞藻 6803（ΔPSI）菌株中表达了一种绿色吸收的类视紫红质蛋白。与ΔPSI 对照菌株相比，对表达类视紫红质蛋白的菌株的生长速率测量、竞争实验和生理特性的研究表明，类视紫红质蛋白可以提高ΔPSI 集胞藻菌株的光异养生长速率。生理特性包括测量废培养基中残留葡萄糖的量以及分析耗氧率和产氧率。为了探索利用 PAR 区域以外的太阳辐射，在视网膜缺失的聚光叶绿素 a 蛋白缺失菌株（ΔPSI/ΔSynACO）中表达了一种红色移位变体类视紫红质蛋白 D212N/F234S。通过外加视黄醛类似物，在体内重新形成了一种红外吸收色素（最大吸收在 740nm 处）。然而，用 746nm 的光照射时，它并没有显著刺激这种突变体的生长（速率）。表达类视紫红质蛋白的ΔPSI 菌株不能进行光自养生长，这很可能是由于其 NADP 还原中的 NADPH 脱氢酶的动力学限制，而不是热力学限制。
