Porins are required for uptake of phosphates by Mycobacterium smegmatis.
Porins are required for uptake of phosphates by Mycobacterium smegmatis.
复制标题
耻垢分枝杆菌吸收磷酸盐需要孔蛋白。
DOI：
10.1128/jb.01600-06
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发表时间：
2007
影响因子：
3.2
通讯作者：
Niederweis,Michael
中科院分区：
文献类型：
--
作者：
Wolschendorf,Frank;Mahfoud,Maysa;Niederweis,Michael
磷是一种必需的营养素，但磷酸盐如何穿过分枝杆菌细胞壁尚不清楚。耻垢分枝杆菌全细胞中的磷酸酶活性明显低于裂解细胞，表明对底物的接触受到限制。与裂解细胞相比，外膜（OM）孔蛋白MspA的损失也降低了全细胞中的磷酸酶活性。对M. smegmatisthat过表达内源性碱性磷酸酶，表明PhoA不是表面蛋白，与以前的报告相反。缺乏孔蛋白MspA和MspC的突变体对磷酸盐的摄取比野生型M低两倍。恶臭引人注目的是，这些孔蛋白的丢失导致了M的严重生长缺陷。在低磷酸盐平板上涂抹。我们的结论是，OM ofM。smegmatis代表磷酸盐的渗透屏障，Msp孔蛋白是磷酸盐在M中扩散的唯一OM通道。恶臭然而，通过Msp孔的磷酸盐扩散是相当低效的，如由10倍的低渗透性ofM所示。与葡萄糖相比，smegmatisfor磷酸盐。这可能是由于Msp孔蛋白的收缩区中的负电荷。牛分枝杆菌BCG全细胞的磷酸酶活性明显低于裂解细胞，表明缓慢生长的分枝杆菌对磷酸盐的摄取途径相似。然而，孔蛋白，可以介导的磷酸盐扩散穿过OM的M。牛卡介苗和结核分枝杆菌是未知的。
Phosphorus is an essential nutrient, but how phosphates cross the mycobacterial cell wall is unknown. Phosphatase activity in whole cells ofMycobacterium smegmatiswas significantly lower than that in lysed cells, indicating that access to the substrate was restricted. The loss of the outer membrane (OM) porin MspA also reduced the phosphatase activity in whole cells compared to that in lysed cells. A similar result was obtained forM. smegmatisthat overexpressed endogenous alkaline phosphatase, indicating that PhoA is not a surface protein, contrary to a previous report. The uptake of phosphate by a mutant lacking the porins MspA and MspC was twofold lower than that by wild-typeM. smegmatis. Strikingly, the loss of these porins resulted in a severe growth defect ofM. smegmatison low-phosphate plates. We concluded that the OM ofM. smegmatisrepresents a permeability barrier for phosphates and that Msp porins are the only OM channels for the diffusion of phosphate inM. smegmatis. However, phosphate diffusion through Msp pores is rather inefficient as shown by the 10-fold lower permeability ofM. smegmatisfor phosphate compared to that for glucose. This is likely due to the negative charges in the constriction zone of Msp porins. The phosphatase activity in whole cells ofMycobacterium bovisBCG was significantly less than that in lysed cells, indicating a similar uptake pathway for phosphates in slow-growing mycobacteria. However, porins that could mediate the diffusion of phosphates across the OM ofM. bovisBCG andMycobacterium tuberculosisare unknown.