Affiliation:
1. Facultad de Ciencias Exactas y Naturales, Departamento de Quı́mica Biológica, Ciudad Universitaria, Universidad de Buenos Aires, 1428 Buenos Aires, Argentina,1 and
2. Unité des Bacteries Entomopathogenes, Institut Pasteur, 75724 Paris Cedex 15, France2
Abstract
ABSTRACT
In the same way that
cry
genes, coding for larvicidal delta endotoxins, constitute a large and diverse gene family, the
cyt
genes for hemolytic toxins seem to compose another set of highly related genes in
Bacillus thuringiensis
. Although the occurrence of Cyt hemolytic factors in
B. thuringiensis
has been typically associated with mosquitocidal strains, we have recently shown that
cyt
genes are also present in strains with different pathotypes; this is the case for the
morrisoni
subspecies, which includes strains biologically active against dipteran, lepidopteran, and coleopteran larvae. In addition, while one Cyt type of protein has been described in all of the mosquitocidal strains studied so far, the present study confirms that at least two Cyt toxins coexist in the more toxic antidipteran strains, such as
B. thuringiensis
subsp.
israelensis
and subsp.
morrisoni
PG14, and that this could also be the case for many others. In fact, PCR screening and Western blot analysis of 50
B. thuringiensis
strains revealed that
cyt
2-related genes are present in all strains with known antidipteran activity, as well as in some others with different or unknown host ranges. Partial DNA sequences for several of these genes were determined, and protein sequence alignments revealed a high degree of conservation of the structural domains. These findings point to an important biological role for Cyt toxins in the final in vivo toxic activity of many
B. thuringiensis
strains.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
51 articles.
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