Genetic dissection of trehalose biosynthesis in Corynebacterium glutamicum:: inactivation of trehalose production leads to impaired growth and an altered cell wall lipid composition
Genetic dissection of trehalose biosynthesis in Corynebacterium glutamicum:: inactivation of trehalose production leads to impaired growth and an altered cell wall lipid composition
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DOI：
10.1099/mic.0.26205-0
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发表时间：
2003-07-01
期刊：
影响因子：
2.8
通讯作者：
Liebl, W
中科院分区：
文献类型：
--
作者：
Tzvetkov, M;Klopprogge, C;Liebl, W
对棒状杆菌基因组序列数据的分析表明，细菌中存在所有三种已知的海藻糖生物合成途径，即从udp -葡萄糖和葡萄糖6-磷酸合成海藻糖（OtsA-OtsB途径），从麦芽糖低聚糖或α -1,4-葡聚糖合成海藻糖（TreY-TreZ途径），或从麦芽糖合成海藻糖（TreS途径）。通过染色体缺失使三种途径中的一种失活并不会对谷氨酰胺的生长产生严重影响，而同时使OtsA-OtsB和TreY-TreZ途径失活或三种途径同时失活会导致相应的突变体无法合成海藻糖，也无法在少量培养基中在各种糖底物上有效生长。在培养液中加入海藻糖后，这种生长缺陷在很大程度上得到了扭转。此外，还发现了一种涉及糖原合成酶（GlgA）的adp -葡萄糖合成糖原的可能途径。在糖过量的条件下生长时，发现谷氨酸梭菌积累了大量的糖原。在DeltaotsAB背景下，染色体glgA基因的插入失活导致C. glutamicum细胞积累糖原的失败，并导致海藻糖生产的终止，这表明通过TreY-TreZ途径生产海藻糖依赖于功能性糖原生物合成途径。失活OtsA-OtsB和TreY-TreZ通路的不产生海藻糖的突变体在缺乏海藻糖的少量肉汤中生长时，细胞壁脂质组成发生了变化。在这些条件下，突变体的细胞壁脂质部分缺乏两种主要的含海藻糖的糖脂，即海藻糖单根藓酸盐和海藻糖二根藓酸盐。结果表明，不含海藻糖的谷氨酰胺突变体细胞壁脂质双分子层的显著改变可能是这种菌株在最低培养基中生长不足的原因。本文报道的谷氨酰胺海藻糖生物合成的遗传和生理解剖结果可能对含霉菌酸棒状细菌的整个系统发育群具有普遍的相关性。
The analysis of the available Corynebacterium genome sequence data led to the proposal of the presence of all three known pathways for trehalose biosynthesis in bacteria, i.e. trehalose synthesis from UDP-glucose and glucose 6-phosphate (OtsA-OtsB pathway), from malto-oligosaccharides or alpha-1,4-glucans (TreY-TreZ pathway), or from maltose (TreS pathway). Inactivation of only one of the three pathways by chromosomal deletion did not have a severe impact on C. glutamicum growth, while the simultaneous inactivation of the OtsA-OtsB and TreY-TreZ pathway or of all three pathways resulted in the inability of the corresponding mutants to synthesize trehalose and to grow efficiently on various sugar substrates in minimal media. This growth defect was largely reversed by the addition of trehalose to the culture broth. In addition, a possible pathway for glycogen synthesis from ADP-glucose involving glycogen synthase (GlgA) was discovered. C. glutamicum was found to accumulate significant amounts of glycogen when grown under conditions of sugar excess. Insertional inactivation of the chromosomal glgA gene led to the failure of C. glutamicum cells to accumulate glycogen and to the abolition of trehalose production in a DeltaotsAB background, demonstrating that trehalose production via the TreY-TreZ pathway is dependent on a functional glycogen biosynthetic route. The trehalose-non-producing mutant with inactivated OtsA-OtsB and TreY-TreZ pathways displayed an altered cell wall lipid composition when grown in minimal broth in the absence of trehalose. Under these conditions, the mutant lacked both major trehalose-containing glycolipids, i.e. trehalose monocorynomycolate and trehalose dicorynomycolate, in its cell wall lipid fraction. The results suggest that a dramatically altered cell wall lipid bilayer of trehalose-less C. glutamicum mutants may be responsible for the observed growth deficiency of such strains in minimal medium. The results of the genetic and physiological dissection of trehalose biosynthesis in C. glutamicum reported here may be of general relevance for the whole phylogenetic group of mycolic-acid-containing coryneform bacteria.