MALTOSE TRANSPORT IN MEMBRANE-VESICLES OF ESCHERICHIA-COLI IS LINKED TO ATP HYDROLYSIS
MALTOSE TRANSPORT IN MEMBRANE-VESICLES OF ESCHERICHIA-COLI IS LINKED TO ATP HYDROLYSIS
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DOI：
10.1073/pnas.86.23.9134
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发表时间：
1989-12-01
影响因子：
11.1
通讯作者：
NIKAIDO, H
中科院分区：
文献类型：
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作者：
DEAN, DA;DAVIDSON, AL;NIKAIDO, H
我们研究了来自大肠杆菌的直立膜小泡中麦芽糖运输的能量需求。当产生系留麦芽糖结合蛋白的菌株将球体稀释到磷酸盐缓冲液中时，来自含F0F1 ATPase(UNC+)菌株的膜小泡在外源电子供体(如抗坏血酸/吩嗪甲硫酸盐)的存在下以每毫克蛋白1-5nmol/min的速率运输麦芽糖，而来自同基因UNC-菌株的膜小泡不转运麦芽糖。如果囊泡含有NAD+和ATP或ATP再生系统，则从后者获得的囊泡在电子供体存在的情况下可以恢复运输。由于不可水解性的ATP类似物不能维持转运，因此显然需要ATP水解物进行转运。麦芽糖转运显著增加了来自UNC-细胞的含ATP囊泡中的ATP水解率。最后，在没有电子供体的情况下，来自产生正常麦芽糖结合蛋白的UNC菌株的含有ATP的囊泡可以积累麦芽糖。这些结果提供了令人信服的证据，证明是ATP的水解驱动了麦芽糖的运输，可能也是其他依赖于周质结合蛋白的运输系统。
We examined the energy requirement for maltose transport in right-side-out membrane vesicles derived from Escherichia coli. When membrane vesicles were made from strains producing tethered maltose-binding proteins by dilution of spheroplasts into phosphate buffer, those from an F0F1 ATPase-containing (unc+) strain transported maltose in the presence of an exogenous electron donor, such as ascorbate/phenazine methosulfate, at a rate of 1-5 nmol/min per mg of protein, whereas those from an isogenic unc- strain failed to transport maltose. Transport in vesicles obtained from the latter strain could be restored in the presence of electron donors if the vesicles were made to contain NAD+ and either ATP or an ATP-regenerating system. ATP hydrolysis was apparently required for transport, since nonhydrolyzable ATP analogues did not sustain transport. Maltose transport significantly increased ATP hydrolysis in ATP-containing vesicles from unc- cells. Finally, ATP-containing vesicles from unc- strains producing normal maltose-binding proteins could accumulate maltose in the absence of electron donors. These results provide convincing evidence that it is the hydrolysis of ATP that drives maltose transport, and probably also other periplasmic-binding-protein-dependent transport systems.