α-Tocopherol Is Essential for Acquired Chill-Light Tolerance in the Cyanobacterium Synechocystis sp. Strain PCC 6803

Abstract

Unlike Escherichia coli, the cyanobacterium Synechocystis sp. strain PCC 6803 is insensitive to chill (5°C) in the dark but rapidly losses viability when exposed to chill in the light (100 mol photons m ؊2 s ؊1 ). Preconditioning at a low temperature (15°C) greatly enhances the chill-light tolerance of Synechocystis sp. strain PCC 6803. This phenomenon is called acquired chill-light tolerance (ACLT). Preconditioned wild-type cells maintained a substantially higher level of ␣-tocopherol after exposure to chill-light stress. Mutants unable to synthesize ␣-tocopherol, such as slr1736, slr1737, slr0089, and slr0090 mutants, almost completely lost ACLT. When exposed to chill without light, these mutants showed no or a slight difference from the wild type. When complemented, the slr0089 mutant regained its ACLT. Copper-regulated expression of slr0090 from P petE controlled the level of ␣-tocopherol and ACLT. We conclude that ␣-tocopherol is essential for ACLT of Synechocystis sp. strain PCC 6803. The role of ␣-tocopherol in ACLT may be based largely on a nonantioxidant activity that is not possessed by other tocopherols or pathway intermediates.

Role of Rbp1 in the Acquired Chill-Light Tolerance of Cyanobacteria

“…Studies with Synechocystis sp. strain PCC 6803 (here referred to as Synechocystis) showed that a unicellular cyanobacterium could acquire chill (5°C)-light (100 mol photons m Ϫ2 s Ϫ1 ) tolerance after preconditioning at a suboptimal low temperature, such as 15°C (26). A similar phenomenon was also found in the bloom-forming species Microcystis sp.…”

“…A similar phenomenon was also found in the bloom-forming species Microcystis sp. (26). These findings suggest that cyanobacteria may develop the capability to overwinter in early winter, or before, when water temperatures decrease.…”

“…However, because it is almost not induced within 24 h at 15°C, ccr1 is probably not the key factor for the development of chill-light tolerance during preconditioning. In the same cyanobacterium, ␣-tocopherol was shown to be essential to the ACLT, but its level was only slightly increased within 48 h of preconditioning (26). The slight increase of ␣-tocopherol is not sufficient to explain the great increase of chill-light tolerance.…”

“…In Synechocystis, chill-light tolerance is rapidly increased within 24 h of preconditioning (26). ccr1 (sll1242, previously called ccr-1) is a gene required for growth at 15°C (27).…”

Simulation on the sediments affecting <i>Microcystis</i> recruitment in north bay of Lake Dianchi

“…Yin 等通过对 PCC6803 的研究发现, 该藻株对低温光照条件敏感, 不利于藻株存活 [17] ; Yang 等进一步研究发现藻株内 α-维生素 E 含量增加对其存活率提升有较大影响 [18] ; 而 Wan 等的最新研究结果揭示了微囊藻在为期 31d 的底泥环境中, 显示出了一定的抗逆性, 且 PS II 活性能较快恢复 [19] . 泊富营养化调查规范》 (第二版) [20] ; 同时使用血球计数板对微囊藻细胞进行计数, 微囊藻细胞净复苏率定 义为每天装置内收集到的微囊藻细胞数除以装置的截面积(相当于底泥面积).…”