Department of Chemistry-Ångström Laboratory, Uppsala University, Box 523, SE 75120 Uppsala, Swedens.
FEMS Microbiol Lett. 2018 Sep 1;365(18). doi: 10.1093/femsle/fny198.
The filamentous cyanobacterium Nostoc punctiforme has several oxidative stress-managing systems, including Dps proteins. Dps proteins belong to the ferritin superfamily and are involved in abiotic stress management in prokaryotes. Previously, we found that one of the five Dps proteins in N. punctiforme, NpDps2, was critical for H2O2 tolerance. Stress induced by high light intensities is aggravated in N. punctiforme strains deficient of either NpDps2, or the bacterioferritin-like NpDps5. Here, we have investigated the capacity of NpDps2 and NpDps5 to enhance stress tolerance by homologous overexpression of these two proteins in N. punctiforme. Both overexpression strains were found to tolerate twice as high concentrations of added H2O2 as the control strain, indicating that overexpression of either NpDps2 or NpDps5 will enhance the capacity for H2O2 tolerance. Under high light intensities, the overexpression of the two NpDps did not enhance the tolerance against general light-induced stress. However, overexpression of the heterocyst-specific NpDps5 in all cells of the filament led to a higher amount of chlorophyll-binding proteins per cell during diazotrophic growth. The OENpDps5 strain also showed an increased tolerance to ammonium-induced oxidative stress. Our results provide information of how Dps proteins may be utilised for engineering of cyanobacteria with enhanced stress tolerance.
丝状蓝藻念珠藻有几种应对氧化应激的管理系统，包括 Dps 蛋白。Dps 蛋白属于铁蛋白超家族，参与原核生物的非生物胁迫管理。以前，我们发现念珠藻的五个 Dps 蛋白之一，NpDps2，对于 H2O2 耐受性是至关重要的。在缺乏 NpDps2 或细菌铁蛋白样 NpDps5 的念珠藻菌株中，高强度光照引起的应激会加剧。在这里，我们通过同源过表达这两种蛋白来研究 NpDps2 和 NpDps5 增强应激耐受性的能力。结果发现，这两个过表达菌株能够耐受比对照菌株高两倍的 H2O2 浓度，表明过表达 NpDps2 或 NpDps5 都会增强 H2O2 耐受性。在高光强下，两种 NpDps 的过表达并没有增强对一般光诱导应激的耐受性。然而，在丝状藻的所有细胞中过表达异形胞特异性的 NpDps5 会导致固氮生长过程中每个细胞的叶绿素结合蛋白数量增加。OENpDps5 菌株对铵诱导的氧化应激也表现出更高的耐受性。我们的研究结果提供了 Dps 蛋白如何用于工程设计具有增强应激耐受性的蓝藻的信息。
