THE AMINO-ACID-SEQUENCE OF 2 NON-TOXIC MUTANTS OF DIPHTHERIA-TOXIN - CRM45 AND CRM197
THE AMINO-ACID-SEQUENCE OF 2 NON-TOXIC MUTANTS OF DIPHTHERIA-TOXIN - CRM45 AND CRM197
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DOI：
10.1093/nar/12.10.4063
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发表时间：
1984-01-01
影响因子：
14.9
通讯作者：
RATTI, G
中科院分区：
文献类型：
--
作者：
GIANNINI, G;RAPPUOLI, R;RATTI, G
根据白喉毒素相关的两个无毒蛋白质CRM 45和CRM 197的基因全序列推导出它们的氨基酸序列：tox 45和tox 197。CRM 45缺少最后149个C-末端氨基酸残基，但在其他方面与白喉毒素相同：单个C→T转换在苏氨酸-386密码子之后引入了“赭石”（TAA）终止信号inox 45。还发现了一个单一的G→A转换，导致CRM 197中存在于野生型毒素中的甘氨酸-52被谷氨酸取代。这种氨基酸变化是导致CRM 197中NAD：EF 2 ADP-核糖基转移酶活性丧失的原因，这可能主要是由于NAD+结合位点的改变。
The amino-acid sequences of two diphtheria toxin-related, non-toxic proteins, CRM45 and CRM197, were deduced from the complete sequence of their genes:tox45 andtox197. CRM45 lacks the last 149 C-terminal amino-acid residues, but is otherwise identical to diphtheria toxin: a single C→T transition introduces an “ochre” (TAA) termination signal intox45, after the codon for threonine-386. A single G→A transition was also found intox197, leading to the substitution of glycine-52, present in the wild-type toxin, with glutamic acid in CRM197. This aminoacid change is responsible for the loss of the NAD:EF2 ADP-riboayltransferase activity in CRM197, due moat probably to an alteration of the NAD+binding site.