Open AccessHeterogeneity in the molecular species of heat‐stable enterotoxin of Vibrio cholerae non‐O1 expressed by Escherichia coli carrying the cloned toxin gene
Author(s) -
Dohi Sekiko,
Kasuga Hidehiko,
Nakao Hiroshi,
Ogawa Akira,
Nair G. Balakrish,
Takeda Tae
Publication year - 1993
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1993.tb05963.x
Subject(s) - periplasmic space , vibrio cholerae , heat stable enterotoxin , escherichia coli , enterotoxin , biology , toxin , microbiology and biotechnology , recombinant dna , vibrionaceae , cholera toxin , molecular cloning , biochemistry , bacteria , peptide sequence , gene , genetics
The biological activity of the heat‐stable enterotoxin of Vibrio cholerae non‐O1 (NAG‐ST) was found to be predominantly associated with the periplasmic extract (about four‐fold higher than the culture supernatant) of a recombinant E. coli (JM109) strain carrying the NAG‐St toxin gene. Four molecular species of NAG‐ST, two each from the periplasmic extract and culture supernatant of JM109, were purified. Amino acid sequence analysis of the four NAG‐ST peptides isolated by HPLC revealed that they all differed from that of the mature 17‐amino acid residue NAG‐ST released by V. cholerae non‐O1. The M r ‐values of the peptides obtained from the periplasmic extract were 4331 and 2785, while those recovered from the culture supernatant were 3154 and 2785. It thus appears that V. cholerae NAG‐ST is synthesized as larger molecules in the recombinant E. coli strain. The differences in sizes of the exported NAG‐ST molecule could relate to difference in the enzyme cleavage system between E. coli and V. cholerea .