Liu Yaqun, Shang Liguo, Zhan Yuhua, Lin Min, Liu Zhu, Yan Yongliang
School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570100, China.
Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Microorganisms. 2020 Apr 19;8(4):592. doi: 10.3390/microorganisms8040592.
Pseudomonas stutzeri A1501 possesses an extraordinary number of transporters which confer this rhizosphere bacterium with the sophisticated ability to metabolize various carbon sources. However, sugars are not a preferred carbon source for P. stutzeri A1501. The P. stutzeri A1501 genome has been sequenced, allowing for the homology-based in silico identification of genes potentially encoding sugar-transport systems by using established microbial sugar transporters as a template sequence. Genomic analysis revealed that there were 10 sugar transporters in P. stutzeri A1501, most of which belong to the ATP-binding cassette (ABC) family (5/10); the others belong to the phosphotransferase system (PTS), major intrinsic protein (MIP) family, major facilitator superfamily (MFS) and the sodium solute superfamily (SSS). These systems might serve for the import of glucose, galactose, fructose and other types of sugar. Growth analysis showed that the only effective medium was glucose and its corresponding metabolic system was relatively complete. Notably, the loci of glucose metabolism regulatory systems HexR, GltR/GtrS, and GntR were adjacent to the transporters ABC, ABC, and ABC, respectively. Only the ABC expression was significantly upregulated under both glucose-sufficient and -limited conditions. The predicted structure and mutant phenotype data of the key protein GtsA provided biochemical evidence that P. stutzeri A1501 predominantly utilized the ABC transporter for glucose uptake. We speculate that gene absence and gene diversity in P. stutzeri A1501 was caused by sugar-deficient environmental factors and hope that this report can provide guidance for further analysis of similar bacterial lifestyles.
斯氏假单胞菌A1501拥有数量众多的转运蛋白，这些转运蛋白赋予了这种根际细菌代谢多种碳源的复杂能力。然而，糖类并非斯氏假单胞菌A1501的首选碳源。斯氏假单胞菌A1501的基因组已被测序，这使得我们能够以已建立的微生物糖转运蛋白为模板序列，通过基于同源性的计算机分析来鉴定可能编码糖转运系统的基因。基因组分析表明，斯氏假单胞菌A1501中有10种糖转运蛋白，其中大多数属于ATP结合盒（ABC）家族（5/10）；其他的则属于磷酸转移酶系统（PTS）、主要内在蛋白（MIP）家族、主要易化子超家族（MFS）和钠溶质超家族（SSS）。这些系统可能用于葡萄糖、半乳糖、果糖和其他类型糖类的转运。生长分析表明，唯一有效的培养基是葡萄糖，其相应的代谢系统相对完整。值得注意的是，葡萄糖代谢调节系统HexR、GltR/GtrS和GntR的基因座分别与转运蛋白ABC、ABC和ABC相邻。只有ABC的表达在葡萄糖充足和有限的条件下均显著上调。关键蛋白GtsA的预测结构和突变体表型数据提供了生化证据，表明斯氏假单胞菌A1501主要利用ABC转运蛋白摄取葡萄糖。我们推测，斯氏假单胞菌A1501中基因的缺失和多样性是由缺糖的环境因素造成的，希望本报告能为进一步分析类似细菌的生活方式提供指导。
