Molecular characterization of a novel chitinase from Bacillus thuringiensis subsp. kurstaki

Abstract

Aims: The present work aims to study a new chitinase from Bacillus thuringiensis subsp. kurstaki. Methods and Results: BUPM255 is a chitinase-producing strain of B. thuringiensis, characterized by its high chitinolytic and antifungal activities. The cloning and sequencing of the corresponding gene named chi255 showed an open reading frame of 2031 bp, encoding a 676 amino acid residue protein. Both nucleotide and amino acid sequences similarity analyses revealed that the chi255 is a new chitinase gene, presenting several differences from the published chi genes of B. thuringiensis. The identification of chitin hydrolysis products resulting from the activity, exhibited by Chi255 through heterologous expression in Escherichia coli revealed that this enzyme is a chitobiosidase. Conclusions: Another chitinase named Chi255 belonging to chitobiosidase class was evidenced in B. thuringiensis subsp. kurstaki and was shown to present several differences in its amino acid sequence with those of published ones. The functionality of Chi255 was proved by the heterologous expression of chi255 in E. coli. Significance and Impact of the Study: The addition of the sequence of chi255 to the few sequenced B. thuringiensis chi genes might contribute to a better investigation of the chitinase Ôstructure-functionÕ relation.

YvoA and CcpA Repress the Expression of chiB in Bacillus thuringiensis

“…Bacillus thuringiensis (Bt) also produces chitinases (4)(5)(6). Several studies have reported that chitinases generated by Bt are involved in its antifungal activity and can enhance the insecticidal activity of Bt strains (7)(8)(9)(10).…”

Construction of a Promoter-probe Vector for Bacillus thuringiensis: the Identification of cis-acting Elements of the chiA Locus

“…However, the production of chitinase increased steadily during vegetative growth and reached a maximum after 70 h [11]. In this study, expression from the chiA promoter seemed to start at the post exponential growth phase (6 h) and almost reached a maximum at the middle of the stationary phase (14 h).…”

“…Possible promoters of some chitinase genes in B. cereus and Bt exhibit homology with the -35 (TTGACA) and -10 (TATAAT) consensus sequences for an E. coli promoter and B. subtilis r A , indicating that the expression of these chitinase genes occurs during the vegetative growth phase [2,11,28,35]. However, the production of chitinase increased steadily during vegetative growth and reached a maximum after 70 h [11].…”

“…Several chitinase genes of Bt have been cloned and characterized [4,11,21,35]. However, knowledge of chitinase gene expression in Bt is limited [33].…”

Isolation of the Bacillus thuringiensis plasmid carrying Bacthuricin F4 coding genes and evidence of its conjugative transfer

“…B. thuringiensis is the most known insecticidal bacterium worldwide for the control of various plant pests. This bacterium produces many virulent factors such as chitinase [6,7] vegetative insecticidal proteins [8], and bacteriocins [9,10]. Bacteriocins are extracellularly released peptides or proteins affecting growth of closely related bacteria and several pathogenic species [9].…”