One face of a transmembrane helix is crucial in mechanosensitive channel gating
One face of a transmembrane helix is crucial in mechanosensitive channel gating
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DOI：
10.1073/pnas.95.19.11471
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发表时间：
1998-09-15
影响因子：
11.1
通讯作者：
Kung, C
中科院分区：
文献类型：
--
作者：
Ou, XR;Blount, P;Kung, C
MscL是细菌中的机械敏感通道，其通过打开大的传导孔直接响应于膜张力。为了确定该分子中功能重要的残基，我们随机诱变mscL，在活细菌中表达基因，并筛选生长受阻的功能获得性突变体。这些基因的表达导致细胞质溶质在很少或没有低渗胁迫下渗漏。在切除的补丁，突变通道门控在膜张力，小于门控野生型MscL所需的。因此，数据表明，生长减缓或无生长表型是由于通道门控不当导致的溶质损失引起的。大多数突变定位于第一个跨膜结构域。当该结构域被建模为α-螺旋时，最严重的突变是在一个面上的较小氨基酸（三个甘氨酸和一个缬氨酸）的取代，这表明该结构在MS通道门控中的重要作用。
MscL is a mechanosensitive channel in bacteria that responds directly to membrane tension by opening a large conductance pore. To determine functionally important residues within this molecule, we have randomly mutagenized mscL, expressed the genes in living bacteria, and screened for gain-of-function mutants with hampered growth, Expression of these genes caused leakage of cytoplasmic solutes on little or no hypo-osmotic stress. In excised patches, the mutant channels gated at membrane tensions that are less than that required for the gating of the wild-type MscL. Hence, the data suggest that the slowed or no-growth phenotype is caused by solute loss because of inappropriate gating of the channel, Most of the mutations mapped to the first transmembrane domain. When this domain is modeled as an alpha-helix, the most severe mutations are substitutions of smaller amino acids (three glycines and one valine) on one facet, suggesting an important role for this structure in MS channel gating.