来自血红色蓖麻的蓖麻毒素A链：DNA序列、结构与毒性。

Ricin A Chain from Ricinus sanguineus: DNA sequence, structure and toxicity.

作者信息

El-Nikhely N, Helmy M, Saeed H M, Abou Shama L A, Abd El-Rahman Z

机构信息

Department of Biotechnology, Institute of Graduate Studies and Research, Alexandria University, Alexandria, Egypt.

出版信息

Protein J. 2007 Oct;26(7):481-9. doi: 10.1007/s10930-007-9088-x.

DOI:10.1007/s10930-007-9088-x

PMID:17687522

Abstract

The gene coding for the ricin A-chain from Ricinus sanguineus (RsTA) was isolated and sequenced (GB: DQ661048). Comparison of RsTA with the ricin A-chain from Ricinus communis (RTA) revealed the presence of five differences in the gene sequence. At the protein level only two differences were noticed, the replacement of Asn136 by Ser (N136S) and Ile173 by Val (I174 V). From the RsTA structure model (PMDB: PM0074652), the N136S mutation was predicted to have no effect on RsTA structure. The I174V mutation is believed to have no effect on the RsTA structure or on toxicity since this replacement was found in the Ricinus agglutinin's A-chain and the latter has a comparable toxicity to RTA. The Ser221 of the putative lipase active site was found. Toxicity experiments showed that RsTA and RTA have similar toxicities. This finding proves that the N136S and I174 V mutations have no effect on RsTA toxicity.

摘要

分离并测序了来自蓖麻（RsTA）的蓖麻毒素A链编码基因（GB：DQ661048）。将RsTA与蓖麻（RTA）的蓖麻毒素A链进行比较，发现基因序列存在五个差异。在蛋白质水平上，仅发现两个差异，即Asn136被Ser取代（N136S）以及Ile173被Val取代（I174V）。从RsTA结构模型（PMDB：PM0074652）预测，N136S突变对RsTA结构没有影响。I174V突变被认为对RsTA结构或毒性没有影响，因为这种取代在蓖麻凝集素的A链中也有发现，且后者与RTA具有相当的毒性。发现了假定脂肪酶活性位点的Ser221。毒性实验表明RsTA和RTA具有相似的毒性。这一发现证明N136S和I174V突变对RsTA毒性没有影响。