大肠杆菌K12冷冻断裂包膜的负染色

Negative staining of freeze-fractured envelopes of Escherichia coli K12.

作者信息

Nermut M V, Burdett I D, Williams L D

出版信息

J Microsc. 1978 Nov;114(2):229-39. doi: 10.1111/j.1365-2818.1978.tb00133.x.

DOI:10.1111/j.1365-2818.1978.tb00133.x

Abstract

Envelope fragments of E. coli K12 have been produced by freeze-fracturing "by hand" and negatively stained after thawing. The outer leaflet of the plasma membrane disintegrated upon thawing whereas the outer leaflet of the outer membrane did not. Negative staining revealed the following structural features on the outer membrane fragments: (i) "grooves" 4-6 nm wide, (ii) spherical particles 6-8 nm in diameter, (iii) "black dots" 3-8 nm in diameter. Treatment of cells with EDTA before freeze-fracturing caused dilation of grooves into holes eventually leading to fragmentation of the outer membrane. A mutant strain deficient in two outer membrane proteins fractured exclusively through the outer membrane. The outer leaflets so obtained disintegrated upon thawing similarly as observed for the outer leaflet of the plasma membrane.

摘要

通过“手工”冷冻断裂法制备了大肠杆菌K12的包膜碎片，并在解冻后进行负染色。质膜的外小叶在解冻时解体，而外膜的外小叶则没有。负染色显示外膜碎片具有以下结构特征：（i）宽4 - 6纳米的“凹槽”，（ii）直径6 - 8纳米的球形颗粒，（iii）直径3 - 8纳米的“黑点”。在冷冻断裂前用EDTA处理细胞会导致凹槽扩张成孔，最终导致外膜破碎。一种缺乏两种外膜蛋白的突变菌株仅在外膜处断裂。如此获得的外小叶在解冻时解体，与质膜外小叶的情况类似。