Clostridium botulinum types A, B, C1, and E produce proteins with or without hemagglutinating activity: Do they share common amino acid sequences and genes?

Abstract

Clostridium botulinum produce the antigenically distinct 150 kD neurotoxin serotypes (e.g., A, B, C1, and E) and simultaneously proteins, A Hn+, B Hn+, C Hn+, and E Hn-, that have high, low, and no hemagglutinating activity. A Hn+ and B Hn+ are serologically cross-reactive. A Hn+, B Hn+, and C Hn+ found as large aggregates (900-220 kD) can be dissociated on SDS-PAGE into multiple subunits, the smallest for A Hn+, B Hn+ is 17 kD and 27 kD for C Hn+. The 116 kD E Hn- does not aggregate. We determined the sequences of 10-33 amino terminal residues of the 17, 21.5, 35, and 57 kD subunits of A Hn+ and B Hn+. Each of these subunits have unique sequences, indicating that the larger units studies are not homomers or heteromers of smaller units. The subunits of A Hn+ and B Hn+ of comparable size have striking sequence identity (e.g., 21.5 kD subunits from the two are identical and 57 kD subunits have 80% identity). In vitro proteolysis of 116 kD E Hn- with different proteases did not impart hemagglutinating activity to the fragments. The 116 kD E Hn- and one of its proteolytic fragments (87 kD) were partially sequenced. Sixty-two base pairs downstream from the termination codon of the cloned 33 kD subunit of C Hn+, there is an initiation codon followed by an open reading frame for at least 34 amino acid residues (Tsuzuki et al., 1990). The derived amino acid sequence of this open reading frame, we found, has 73-84% sequence identity with those of the 17 kD subunits of A Hn+ and B Hn+ and significant identity with the N-terminal of E Hn-. These highly conserved sequences show existence of genetic linkage among the Hn+ and Hn- proteins.

The complete nucleotide sequence of the gene encoding the nontoxic component of Clostridium botulinum type E progenitor toxin

“…The molecular mass calculated from the deduced amino acid sequence was 136849.3 Da, a value slightly higher than that estimated from the blotting analysis described above. The N-terminal amino acid sequence of the ent-120 gene was very similar (22 out of 30 amino acid residues identical) to that of the botulinum type E nontoxic component reported by Somers & DasGupta (1991). The amino acid residues which differ are marked with stars in Fig.…”

Characterization of New Formalin-Detoxified Botulinum Neurotoxin Toxoids

“…BoNTs are bound to many nontoxic clostridial proteins, forming heterogeneous complexes of up to 900 kDa in mass. These complexes consist of one 150-kDa neurotoxin molecule, hemagglutinins (Hmgs) and a variety of other proteins (32). The number and types of proteins associated with the neurotoxin vary with the C. botulinum strain (24).…”

Gene arrangement in the upstream region of Clostridium botulinum type E and Clostridium butyricum BL6340 progenitor toxin genes is different from that of other types

“…L toxin, therefore, shows hemagglutinin activity, but M toxin does not. Botulinum toxins type A, B, C, and D are mixtures of both L and M toxins [1]. Type E and F toxins, and type A toxin from infant botulism in Japan are composed exclusively of M toxin [2,3].…”