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Functional analysis of block 5, one of the highly conserved amino acid sequences in the 130‐kDa CryIVA protein produced by Bacillus thuringiensis subsp. israelensis
Author(s) -
Nishimoto Tomoyuki,
Yoshisue Hajime,
Ihara Kentaro,
Sakai Hiroshi,
Komano Tohru
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)00604-0
Subject(s) - thermolysin , bacillus thuringiensis , amino acid , biochemistry , peptide sequence , trypsin , biology , chemistry , enzyme , bacteria , genetics , gene
There are five amino acid sequences highly conserved among Bacillus thuringiensis δ‐endotoxins. We have changed the amino acid residues in block 5, one of the conserved sequences, of CryIVA. When the amino acid residues with charged side chains were replaced by others, the amount of production of the altered CryIVA protein was markedly decreased. It is suggested that the decrease is caused by the unstable conformation of the altered CryIVA protein molecule, as judged by digestion with trypsin and thermolysin. On the other hand, the substitution of amino acid residues in block 5 did not affect the insecticidal activity of CryIVA. These results strongly suggest that block 5 of CryIVA is one of the stability‐determining elements of the protoxin molecule.