So far, the molecular mechanisms underlying the acidic-stress responses of plants are complicated and only fragmentally understood. Here, we investigated the mechanisms responsible for acidic-stress acclimation. Previously, DNA microarray analysis identified the sll1558 gene in Synechocystis sp. PCC 6803 (hereafter called Synechocystis 6803) to be upregulated following short-term acid treatment (1 h at pH 3.0). The sll1558 gene encodes uridine diphosphate-glucose pyrophosphorylase (UDP-glucose pyrophosphorylase), which catalyzes the conversion of glucose-1-phosphate into UDP-glucose. We constructed mutant cells for this gene and analyzed their phenotype. The sll1558 gene did not completely segregate in sll1558 mutant cells; thus, Sll1558 is essential for the survival of Synechocystis 6803. Besides, the partially disrupted sll1558 mutant cells were highly sensitive to acidic stress (pH 6.0) as well as other stress conditions (high salt, high osmolality, high/low temperature, and ultraviolet-B stress); the number of sll1558 transcripts increased under these conditions. UDP-glucose is used for the synthesis of various materials, such as glycolipids. From the membrane lipid composition analysis, digalactosyldiacylglycerol decreased and phosphatidylglycerol increased in the partially disrupted sll1558 mutant cells under acidic stress. These results suggest that sll1558 is important not only for the survival of Synechocystis 6803, but also for tolerance under various stress conditions.

中文翻译：

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Sll1558 在集胞藻环境胁迫耐受性中的表征。PCC 6803。

到目前为止，植物酸性应激反应的分子机制是复杂的，并且只是零碎地了解。在这里，我们研究了负责酸性应激驯化的机制。以前，DNA 微阵列分析在集胞藻中鉴定了 sll1558 基因。PCC 6803（以下称为集胞藻 6803）在短期酸处理（pH 3.0 下 1 小时）后上调。sll1558 基因编码尿苷二磷酸-葡萄糖焦磷酸化酶（UDP-葡萄糖焦磷酸化酶），催化葡萄糖-1-磷酸转化为UDP-葡萄糖。我们为该基因构建了突变细胞并分析了它们的表型。sll1558基因在sll1558突变细胞中没有完全分离；因此，Sll1558 对集胞藻 6803 的生存至关重要。 此外，部分破坏的sll1558突变细胞对酸性胁迫（pH 6.0）以及其他胁迫条件（高盐、高渗透压、高/低温和紫外线B胁迫）高度敏感；在这些条件下，sll1558 转录本的数量增加了。UDP-葡萄糖用于合成各种材料，如糖脂。从膜脂成分分析来看，在酸性胁迫下，部分破坏的 sll1558 突变细胞中二半乳糖二酰甘油减少而磷脂酰甘油增加。这些结果表明 sll1558 不仅对集胞藻 6803 的存活很重要，而且对各种胁迫条件下的耐受性也很重要。在这些条件下，sll1558 转录本的数量增加了。UDP-葡萄糖用于合成各种材料，如糖脂。从膜脂成分分析来看，在酸性胁迫下，部分破坏的 sll1558 突变细胞中二半乳糖二酰甘油减少而磷脂酰甘油增加。这些结果表明 sll1558 不仅对集胞藻 6803 的存活很重要，而且对各种胁迫条件下的耐受性也很重要。在这些条件下，sll1558 转录本的数量增加了。UDP-葡萄糖用于合成各种材料，如糖脂。从膜脂成分分析来看，在酸性胁迫下，部分破坏的 sll1558 突变细胞中二半乳糖二酰甘油减少而磷脂酰甘油增加。这些结果表明 sll1558 不仅对集胞藻 6803 的存活很重要，而且对各种胁迫条件下的耐受性也很重要。