Santos-Buelga J A, Collins M D, East A K
Department of Microbiology, Institute of Food Research, Earley Gate, Whiteknights Road, Reading, RG6 6BZ, UK.
Curr Microbiol. 1998 Nov;37(5):312-8. doi: 10.1007/s002849900384.
The organization of the clusters of genes encoding proteins of the botulinum neurotoxin (BoNT) progenitor complex was elucidated in a strain of Clostridium botulinum producing type B and F neurotoxins. With PCR and sequencing strategies, the type B BoNT-gene cluster was found to be composed of genes encoding BoNT/B, nontoxic nonhemagglutinin component (NTNH), P-21, and the hemagglutinins HA-33, HA-17, and HA-70, whereas the type F BoNT-gene cluster has genes encoding BoNT/F, NTNH, P-47, and P-21. Comparative sequence analysis showed that BoNT/F in type BF strain 3281 shares highest homology with BoNT/F of non-proteolytic (group II) C. botulinum whereas NTNH and P-21 in the type F cluster of strain 3281 are more similar to the corresponding proteins in proteolytic (group I) type F C. botulinum. These findings indicate diverse evolutionary origins for genes encoding BoNT/F and its associated non-toxic proteins, although the genes are contiguous. By contrast, sequence comparisons indicate that genes encoding BoNT/B and associated non-toxic proteins in strain 3281 possess a similar evolutionary origin. It was demonstrated that the genes present in the BoNT/B gene cluster of this type BF strain show exceptionally high homology with the equivalent genes in the silent BoNT/B gene cluster of C. botulinum type A(B), possibly indicating their common ancestry.
在一株产生B型和F型肉毒杆菌神经毒素的肉毒梭菌中，对编码肉毒杆菌神经毒素（BoNT）前体复合物蛋白的基因簇组织进行了阐明。通过PCR和测序策略，发现B型BoNT基因簇由编码BoNT/B、无毒非血凝素成分（NTNH）、P-21以及血凝素HA-33、HA-17和HA-70的基因组成，而F型BoNT基因簇有编码BoNT/F、NTNH、P-47和P-21的基因。比较序列分析表明，BF型菌株3281中的BoNT/F与非蛋白水解性（II组）肉毒梭菌的BoNT/F具有最高同源性，而菌株3281的F型基因簇中的NTNH和P-21与蛋白水解性（I组）F型肉毒梭菌中的相应蛋白更相似。这些发现表明，尽管编码BoNT/F及其相关无毒蛋白的基因是相邻的，但它们具有不同的进化起源。相比之下，序列比较表明，菌株3281中编码BoNT/B和相关无毒蛋白的基因具有相似的进化起源。已证明，该BF型菌株的BoNT/B基因簇中存在的基因与A型（B）肉毒梭菌沉默BoNT/B基因簇中的等效基因具有极高的同源性，这可能表明它们有共同的祖先。
