ALTERATIONS AT THE CARBOXYL TERMINUS CHANGE ASSEMBLY AND SECRETION PROPERTIES OF THE B-SUBUNIT OF ESCHERICHIA-COLI HEAT-LABILE ENTEROTOXIN
ALTERATIONS AT THE CARBOXYL TERMINUS CHANGE ASSEMBLY AND SECRETION PROPERTIES OF THE B-SUBUNIT OF ESCHERICHIA-COLI HEAT-LABILE ENTEROTOXIN
复制标题
DOI：
10.1128/jb.169.10.4570-4576.1987
复制
发表时间：
1987-10-01
影响因子：
3.2
通讯作者：
BAGDASARIAN, M
中科院分区：
文献类型：
--
作者：
SANDKVIST, M;HIRST, TR;BAGDASARIAN, M
编码不耐热肠毒素B亚单位(EtxB)的基因在其3‘端通过随机核苷酸序列的定向添加而发生突变。对5个突变的etxB基因的基因产物进行了一系列的功能和结构性质的分析，这些基因都被证明编码带有短羧基末端氨基酸延伸的B亚基。一类改变的B亚基，如EtxB124和EtxB138，都有7个额外的氨基酸残基，被发现在与A亚基稳定结合和形成全毒素的能力上存在明显缺陷。其他改变的B亚基受其C末端延伸的影响较小，除了不能与A亚基结合外，还不能移位到大肠杆菌的周质中，不能五聚化，也不能与GM1神经节苷脂结合。这表明EtxB的羧基末端结构域介导了A亚基-B亚基的相互作用。
The gene encoding the B subunit of heat-labile enterotoxin (etxB) was mutated at its 3'' end by targeted addition of random nucleotide sequences. Gene products from five mutated etxB genes, all of which were shown to encode B subunits with short carboxy-terminal amino acid extensions, were analyzed with respect to a range of functional and structural properties. One class of altered B subunits, exemplified by EtxB124 and EtxB138, which both have seven extra amino acid residues, were found to be specifically defective in their ability to stably associate with A subunits and form holotoxin. Other altered B subunits were less subtlety affected by extensions at their C termini and were, in addition to their failure to associate with A subunits, unable to translocate into the periplasm of Escherichia coli, to pentamerize, or to bind to GM1 ganglioside. This suggests that the carboxy-terminal domain of EtxB mediates A subunit-B subunit interaction.