The crystal structure of insecticidal protein Txp40 from Xenorhabdus nematophila reveals a two-domain unique binary toxin with homology to the toxin-antitoxin (TA) system.

Txp40 is a ubiquitous, conserved, and novel toxin from Xenorhabdus and Photorhabdus bacteria, toxic to a wide range of insect pests. However, the three-dimensional structure and toxicity mechanism for Txp40 or any of its sequence homologs are not yet known. Here, we are reporting the crystal structure of the insecticidal protein Txp40 from Xenorhabdus nematophila at 2.

Crystal structures of PirA and PirB toxins from Photorhabdus akhurstii subsp. akhurstii K-1.

PirAB binary toxin from Photorhabdus is toxic to the larvae of dipteran and lepidopteran insect pests. However, the 3-D structures and their toxicity mechanism are not yet fully understood. Here we report the crystal structures of PirA and PirB proteins from Photorhabdus akhurstii subsp.

Purification, characterization and proteolytic processing of mosquito larvicidal protein Cry11Aa from Bacillus thuringiensis subsp. israelensis ISPC-12.

Cry11Aa is the most potent mosquito larvicidal protein of Bacillus thuringiensis subsp. israelensis (Bti). Development of resistance against insecticidal proteins including Cry11Aa is known but no field resistance was observed with Bti.

Purification, characterization and toxicity assessment of PirAB toxins from Photorhabdus akhurstii subsp. akhurstii K-1.

Photorhabdus insect related proteins A & B (PirA, PirB) from Photorhabdus and Xenorhabdus bacteria exhibit both oral and injectable toxicity against lepidopteran and dipteran insect pest. The pirA, pirAt (encoding 6 N-terminal truncated PirA), pirB genes, pirA-pirB (with ERIC sequences), pirA-pirB-mERIC (modified pirA-pirB with mutated ERIC sequences) and polycistronic-pirAB were cloned and expressed in Escherichia coli. However, PirA protein was expressed in insoluble form and therefore the pirA gene was modified to produce PirAt.

Txp40, an insecticidal toxin protein from Xenorhabdus nematophila: Purification, toxicity assessment and biophysical characterization.

Txp40 is a ubiquitous toxin from Xenorhabdus and Photorhabdus bacteria, exhibits insecticidal activity against a wide range of insect pests belonging to Lepidoptera and Diptera orders. Initially, Txp40 affects midgut of the target insect and further damages some other tissues like fat bodies but the detailed mode of action is not known. Txp40 shares no significant sequence match to any proteins with known structure or function, suggesting that it is a novel type of insecticidal toxin.

Detection and characterization of bacterial endosymbionts in Southeast Asian tephritid fruit fly populations.

Background: Various endosymbiotic bacteria, including Wolbachia of the Alphaproteobacteria, infect a wide range of insects and are capable of inducing reproductive abnormalities to their hosts such as cytoplasmic incompatibility (CI), parthenogenesis, feminization and male-killing. These extended phenotypes can be potentially exploited in enhancing environmentally friendly methods, such as the sterile insect technique (SIT), for controlling natural populations of agricultural pests. The goal of the present study is to investigate the presence of Wolbachia, Spiroplasma, Arsenophonus and Cardinium among Bactrocera, Dacus and Zeugodacus flies of Southeast Asian populations, and to genotype any detected Wolbachia strains.

Bacterial communities in the gut of wild and mass-reared Zeugodacus cucurbitae and Bactrocera dorsalis revealed by metagenomic sequencing.

Background: Insect pests belonging to genus Bactrocera sp. (Diptera: Tephritidae) pose major biotic stress on various fruits and vegetable crops around the world. Zeugodacus and Bactrocera sp.

PEGylation Enhances Mosquito-Larvicidal Activity of Lysinibacillus sphaericus Binary Toxin.

Toxic strains of Lysinibacillus sphaericus have been used in the field for larval control of mosquito vector diseases. The high toxicity of L. sphaericus is attributed to the binary (BinAB) toxin produced as parasporal crystalline inclusions during the early stages of sporulation.

Diversity of bacterial communities in the midgut of Bactrocera cucurbitae (Diptera: Tephritidae) populations and their potential use as attractants.

Background: The microbiota plays an important role in insect development and fitness. Understanding the gut microbiota composition is essential for the development of pest management strategies. Midgut bacteria were isolated from nine wild B.

An oligomeric complex of BinA/BinB is not formed in-situ in mosquito-larvicidal Lysinibacillus sphaericus ISPC-8.

Binary toxin of Lysinibacillus sphaericus is composed of two polypeptides; receptor binding BinB and toxic BinA. Both the polypeptides are required for maximal toxicity. It has been suggested that binary toxin exerts toxicity as a heterotetramer constituted by two copies of each of the component polypeptides.

Polymeric macroporous formulations for the control release of mosquitocidal Bacillus sphaericus ISPC-8.

Bio-polymeric mosquitocidal formulations were developed for the control release of Bacillus sphaericus ISPC-8 by the immobilization of its spore-crystal complex onto the macroporous polymeric matrices. The biodegradable formulations were synthesized at sub-zero temperature using natural polymeric substrates like agarose, alginate, cellulose, non-adsorbent cotton, wooden cork powder and also magnetite nanoparticles. The obtained polymeric matrices were morphologically characterized, which showed 85-90% porosity, uniform pores distribution, high permeability and controlled degradation (19-30%) in 4 weeks depending upon the composition of formulations.

Interaction between mosquito-larvicidal Lysinibacillus sphaericus binary toxin components: analysis of complex formation.

The two components (BinA and BinB) of Lysinibacillus sphaericus binary toxin together are highly toxic to Culex and Anopheles mosquito larvae, and have been employed world-wide to control mosquito borne diseases. Upon binding to the membrane receptor an oligomeric form (BinA2.BinB2) of the binary toxin is expected to play role in pore formation.

Transgenic banana plants expressing small interfering RNAs targeted against viral replication initiation gene display high-level resistance to banana bunchy top virus infection.

The banana aphid-transmitted Banana bunchy top virus (BBTV) is the most destructive viral pathogen of bananas and plantains worldwide. Lack of natural sources of resistance to BBTV has necessitated the exploitation of proven transgenic technologies for obtaining BBTV-resistant banana cultivars. In this study, we have explored the concept of using intron-hairpin-RNA (ihpRNA) transcripts corresponding to viral master replication initiation protein (Rep) to generate BBTV-resistant transgenic banana plants.

Characterization of highly toxic indigenous strains of mosquitocidal organism Bacillus sphaericus.

Three indigenous isolates of Bacillus sphaericus (ISPC-5, ISPC-6 and ISPC-8), along with standard 2362 and 1593 strains, were evaluated for spore viability and mosquitocidal activity. Among these, ISPC-8 was the most viable and virulent isolate, exhibiting a significantly higher total viability count (TVC) and lower LC(50) values. The TVC of the standard strains ranged from 4.

Purification and characterization of mosquitocidal Bacillus sphaericus BinA protein.

Certain strains of Bacillus sphaericus produce a highly toxic mosquito-larvicidal binary toxin during sporulation. The binary toxin is composed of toxic BinA (41.9kDa) and receptor binding BinB (51.