Ferramenta web para descoberta e categorização de genes cry

Abstract

Bacillus thuringiensis (Bt) is a spore-forming bacterium that produces Cry, Cyt and Vip toxins as parasporal crystals, which have demonstrated to be effective in controlling agricultural pests and mosquito vectors of diseases. The genes encoding these toxins have been used in the development of insect-resistant transgenic plants. The adoption of Bt biopesticide allows the reduction in the use of synthetic insecticides, and does not offer risks or damages to human health. However, many insect pests are not susceptible to such already identified toxins. So far, more than 700 Cry toxin-related Bt genes have been identified, targeted in this work, classified into more than 70 groups. An alternative for pests that are not susceptible to parental Cry toxins is the isolation of other Bt strains with new cry genes with higher toxicity, as well as the identification of receptor molecules and binding epitopes and the screening of novel Cry proteins with toxicity to new insects. Another alternative is the in vitro genetic evolution of such toxins. To aid in the process of finding new cry genes, a cured cry gene database has been developed and a web tool has been implemented for the identification and categorization of a particular target sequence as belonging to a cry gene family. The entire classification and categorization process combines bioinformatics programs such as HMMER, BEDTools, MUSCLE and BLAST. The tool presents the user with a list of the target sequences with the highest identity to be a cry gene. The user selects one of these sequences to analyze the alignment with public sequences of Bt genes. The same procedure allows to reconstruct the phylogenetic tree through a matrix of similarity to identify the closest relatives. This process can be repeated for all available sequences. The results pointed out that the tool has the ability to support the user in the task of identifying Cry proteins, based on the DNA sequence, in order to describe an existing protein or a new Cry protein, which may present higher toxicity and be employed to act in the pest control and disease vectors in a broad spectrum of action, reaching those currently not sensitive to Cry toxins or that are inefficiently controlled.