Effects of MreB paralogs on poly-γ-glutamic acid synthesis and cell morphology in Bacillus amyloliquefaciens
Effects of MreB paralogs on poly-γ-glutamic acid synthesis and cell morphology in Bacillus amyloliquefaciens
复制标题
MreB 旁系同源物对解淀粉芽孢杆菌多聚 γ-谷氨酸合成和细胞形态的影响
DOI：
10.1093/femsle/fnw187
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发表时间：
2016-09-01
影响因子：
2.1
通讯作者：
Song, Cunjiang
中科院分区：
文献类型：
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作者：
Gao, Weixia;Zhang, Zhongxiong;Song, Cunjiang
肌动蛋白样MreB旁系同源物在细胞形状维持、细胞壁合成和D，L-内肽酶CwlO和LytE的调节中起重要作用。革兰氏阳性细菌，解淀粉芽孢杆菌LL 3，是一种产生聚-γ-谷氨酸（γ-PGA）的菌株，含有三种MreB旁系同源物：MreB、Mbl和MreBH。在B。amyloliquefaciens、CwlO和LytE能降解γ-PGA。在这项研究中，我们的目的是测试的假设，调节转录水平的MreB旁系同源物将改变合成和降解的γ-PGA。结果表明，过表达或抑制MreB、Mbl或MreBH对细胞形态和γ-PGA产物的分子量有明显影响。在发酵培养基中，mreB抑制突变株的细胞比LL 3长50.2%，γ-PGA效价提高了55.7%。然而，改变mbl的表达水平仅显示对形态、γ-PGA分子量和滴度的轻微影响。在mreBH抑制突变体中，γ-PGA产量和分子量分别增加了56.7%和19.4%。这些结果证实了我们的假设，即抑制MreB旁系同源物的表达可能会减少γ-PGA降解，并且改善细胞大小可以加强γ-PGA合成。这是通过抑制肌动蛋白样MreB旁系同源物增强γ-PGA生产的第一份报告。
Actin-like MreB paralogs play important roles in cell shape maintenance, cell wall synthesis and the regulation of the D, L-endopeptidases, CwlO and LytE. The gram-positive bacteria, Bacillus amyloliquefaciens LL3, is a poly-gamma-glutamic acid (gamma-PGA) producing strain that contains three MreB paralogs: MreB, Mbl and MreBH. In B. amyloliquefaciens, CwlO and LytE can degrade gamma-PGA. In this study, we aimed to test the hypothesis that modulating transcript levels of MreB paralogs would alter the synthesis and degradation of gamma-PGA. The results showed that overexpression or inhibition of MreB, Mbl or MreBH had distinct effects on cell morphology and the molecular weight of the gamma-PGA products. In fermentation medium, cells of mreB inhibition mutant were 50.2% longer than LL3, and the gamma-PGA titer increased by 55.7%. However, changing the expression level of mbl showed only slight effects on the morphology, gamma-PGA molecular weight and titer. In the mreBH inhibition mutant, gamma-PGA production and its molecular weight increased by 56.7% and 19.4%, respectively. These results confirmed our hypothesis that suppressing the expression of MreB paralogs might reduce gamma-PGA degradation, and that improving the cell size could strengthen gamma-PGA synthesis. This is the first report of enhanced gamma-PGA production via suppression of actin-like MreB paralogs.