New Variants of Lepidoptericidal Toxin Genes Encoding <b><i>Bacillus thuringiensis</i></b> Vip3Aa Proteins

Abstract

Bacillus thuringiensis is an entomopathogenic bacterium characterized by producing parasporal proteinaceous insecticidal crystal inclusions during sporulation. Many strains are capable of also expressing other insecticidal proteins called Vip during the vegetative growing phase. Particularly, Vip3A proteins have activity against certain Lepidoptera species through a unique mechanism of action which emphasized their possible use in resistance management strategies against resistant pests. The aim of the work was to develop a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method that can distinguish between vip3A genes from B. thuringiensis strains. In addition, 4 novel vip3Aa genes were cloned and sequenced. The method was originally based on amplification of a single PCR amplicon and the use of 2 restriction enzymes with recognition sites that facilitate simultaneous detection. Subsequently, a third restriction enzyme was used to distinguish between vip3A variants. Thirteen vip3Aa genes were identified in strains belonging to 10 different B. thuringiensis serovars. Three intra-subclass variants of vip3Aa genes could be differentiated. The presented method can serve as an invaluable tool for the investigation of known and novel vip3A genes in B. thuringiensis strains. To the best of our knowledge, this is the first report where variants of a same subclass of insecticidal genes could be distinguished following PCR-RFLP.

Relação entre toxicidade de proteínas Vip3Aa e sua capacidade de ligação a receptores intestinais de lepidópteros-praga

“…Esta é uma informação relevante para o manejo da resistência, uma vez que alterações que diminuem a ligação das proteínas com os receptores estão associadas a elevados níveis de resistência às toxinas Cry (Ferré & Van Rie, 2002 Loguercio et al (2002). A segunda linhagem é considerada padrão para vários genes cry1A e cry2, além de também possuir o gene vip3Aa33 -acesso número GU073128 GenBank (2014a), cuja sequência foi submetida por Sauka et al (2012).…”

Bioinformatics Analysis and Functional Prediction of Transmembrane Proteins in Entamoeba histolytica

“…A large number of important pathogens utilize pore-forming toxins for virulence. Transmembrane pores are formed in the membrane of target cell by the proteins that are synthesized by another cell and secreted for insertion [ 36 ]. There were 13 members identified in this class which belong to six distinct families, including one protein from the Serratia -type pore-forming toxin (S-PFT) family (TC 1.C.75), one protein from the Botulinum and tetanus toxin family ( TC 1.C.8 ), two proteins from the clostridial cytotoxin (CCT) family (TC 1.C.57), one protein from the SphH hemolysin (SphH) family (TC 1.C.67), and one protein from the hemolysin III family (TC 1.C.113), while most of the proteins (eight) were from the Bacillus thuringiensis vegetative insecticidal protein-3 family (TC 1.C.105).…”

“…It has been seen that the processes that are dependent on ion channels contribute to the excystation and metacystic development of the parasite inside the host, thus playing a critical role in pathogenesis [ 56 ]. The pore-forming toxin proteins help in pore formation and the penetration of the parasite in the epithelial cell membrane of the host intestine [ 57 ], and they are insecticidal in nature [ 36 ]. These results imply a crucial role played by the different type of channels in parasite biology, suggesting that developing drugs for these parasite-specific channels may be a novel approach for a therapeutic strategy.…”

Caracterização do gene vip3A e toxicidade da proteína Vip3Aa50 à lagarta-do-cartucho e à lagarta-da-soja

“…A proteína Vip3Aa50 apresenta poucas mutações em sua região N-terminal, em comparação a outras proteínas Vip3Aa, o que também foi observado por Sauka et al (2013), para as proteínas Vip3Aa40 e Vip3Aa41.…”