Loss of outer membrane proteins without inhibition of lipid export in an Escherichia coli YaeT mutant
Loss of outer membrane proteins without inhibition of lipid export in an Escherichia coli YaeT mutant
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DOI：
10.1074/jbc.m504796200
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发表时间：
2005-07-29
影响因子：
4.8
通讯作者：
Raetz, CRH
中科院分区：
文献类型：
--
作者：
Doerrler, WT;Raetz, CRH
大肠杆菌yaeT编码一种必需的、保守的外膜（OM）蛋白，其是脑膜炎奈瑟菌Omp 85的直系同源物。用N.脑膜炎表明Omp 85在OM蛋白的组装或OM脂质的输出中起作用。YaeT在E.大肠杆菌中的一个新的温度敏感的突变体harboring 9个氨基酸的取代进行了研究。突变体在44 ℃下60分钟后停止生长。在44 ° C下30分钟后，[S-35]甲硫氨酸掺入新合成的OM蛋白被选择性抑制。OM磷脂和脂多糖的合成和输出不受影响。即使在30摄氏度下，OM蛋白质水平也很低，OM的浮力密度也相应较低。通过Western印迹，我们发现，在整个细胞，膜和生长培养基中的突变体的主要OM蛋白OmpA的水平较低。SecA作为温度敏感表型的多拷贝抑制因子发挥作用，并部分恢复OM蛋白。我们的数据与YaeT在大肠杆菌OM蛋白组装中的关键作用一致。杆菌
Escherichia coli yaeT encodes an essential, conserved outer membrane ( OM) protein that is an ortholog of Neisseria meningitidis Omp85. Conflicting data with N. meningitidis indicate that Omp85 functions either in assembly of OM proteins or in export of OM lipids. The role of YaeT in E. coli was investigated with a new temperature-sensitive mutant harboring nine amino acid substitutions. The mutant stops growing after 60 min at 44 degrees C. After 30 min at 44 degrees C, incorporation of [S-35] methionine into newly synthesized OM proteins is selectively inhibited. Synthesis and export of OM phospholipids and lipopolysaccharide are not impaired. OM protein levels are low, even at 30 degrees C, and the buoyant density of the OM is correspondingly lower. By Western blotting, we show that levels of the major OM protein OmpA are lower in the mutant in whole cells, membranes, and the growth medium. SecA functions as a multicopy suppressor of the temperature-sensitive phenotype and partially restores OM proteins. Our data are consistent with a critical role for YaeT in OM protein assembly in E. coli.