Bacillus thuringiensis Cry toxins are used worldwide as insecticides in agriculture, forestry, and the control of disease transmission vectors. In lepidopteran Manduca sexta, cadherin (Bt-R1) aminopeptidase-N (APN) function Cry1A toxin receptors. The interaction with Bt-R1 promotes cleavage amino-terminal end, including helix α-1 formation prepore oligomer that binds to APN, leading membrane insertion pore formation. Loops domain II Cry1Ab involved receptor interaction. Here we show mutants...

Different Bacillus thuringiensis (Bt) strains produce a broad variety of pore-forming toxins (PFTs) that show toxicity against insects and other invertebrates. Some these insecticidal PFT proteins have been used successfully worldwide to control diverse insect crop pests. There are several studies focused on describing the mechanism action helped improve their performance cope with resistance evolved by different some proteins. However, crucial information is still missing structure pores...

Glycosidases are associated with various human diseases. The development of efficient and specific inhibitors may provide powerful tools to modulate their activity. However, achieving high selectivity is a major challenge given that glycosidases different functions can have similar enzymatic mechanisms active-site architectures. As an alternative approach small-chemical compounds, proteinaceous might better specificity by involving larger surface area interaction. We report here the design...

Transgenic plants that produce Bacillus thuringiensis (Bt) crystalline (Cry) toxins are cultivated worldwide to control insect pests. Resistance B. threatens this technology, and although different resistance mechanisms have been identified, some not completely elucidated. To gain new insights into these mechanisms, we performed multiple back-crossing from a 3000-fold Cry1Ac-resistant BtR strain cotton bollworm (Helicoverpa armigera), isolating 516-fold (96CAD). Cry1Ac in 96CAD was tightly...

The bacterium Bacillus thuringiensis produces several insecticidal proteins, such as the crystal proteins (Cry) and vegetative (Vip). In this work, we report that a specific interaction between two B. toxins creates synergism unravel molecular basis of interaction. When applied together, three-domain Cry toxin Cry9Aa Vip Vip3Aa exhibited high activity against an important insect pest, Asiatic rice borer (Chilo suppressalis). We found these bind specifically to brush border membrane vesicles...

Background Bacillus thuringiensis Cry toxins, that are used worldwide in insect control, kill insects by a mechanism depends on their ability to form oligomeric pores insert into the insect-midgut cells. These toxins being transgenic plants or spray control pests agriculture. However, major concern has been possible effects of these insecticidal proteins non-target organisms mainly ecosystems adjacent agricultural fields. Methodology/Principal Findings We isolated and characterized 11...

The Cyt and Cry toxins are different pore-forming proteins produced by Bacillus thuringiensis bacteria, used in insect-pests control. Cry-toxins have a complex mechanism involving interaction with several the insect gut such as aminopeptidase N (APN), alkaline phosphatase (ALP) cadherin (CAD). It was shown that loop regions of domain II participate receptor binding. Cyt-toxins dipteran specific interact membrane lipids. We show Cry1Ab loop3 is involved binding to APN, ALP CAD receptors since...

Helicobacter pylori is a Gram-negative bacterium that colonizes the human gastric mucosa and responsible for causing peptic ulcers carcinoma. The expression of virulence factors allows persistence H. in stomach, which results chronic, sometimes uncontrolled inflammatory response. Type II toxin-antitoxin systems have emerged as important many pathogenic bacteria. Three type (TA) previously been identified genome 26695: HP0315-HP0316, HP0892-HP0893, HP0894-HP0895. Here we characterized...

The insecticidal Cry11Aa and Cyt1Aa proteins are produced by Bacillus thuringiensis as crystal inclusions. They work synergistically inducing high toxicity against mosquito larvae. It was proposed that these inclusions rapidly solubilized activated in the gut lumen, followed pore formation midgut cells killing In addition, functions a binding receptor, oligomerization membrane insertion. Here, we used fluorescent labeled crystals, protoxins or toxins for vivo localization at nano-scale...

<b><i>Background:</i></b> Gram-negative bacilli are the most common bacteria causing nosocomial bloodstream infections (NBSIs) in Latin American countries. <b><i>Methods:</i></b> The antibiotic resistance profiles of isolated from blood cultures pediatric patients with NBSIs over a 3-year period tertiary care hospital Mexico City were determined using VITEK-2 system. Sixteen antibiotics tested to ascertain rate and minimum inhibitory...

Klebsiella pneumoniae is a common opportunistic pathogen causing nosocomial infections. One of the main virulence determinants K. type 3 pilus (T3P). T3P helps bacterial interaction to both abiotic and biotic surfaces it crucial for biofilm formation. genetically organized in three transcriptional units: mrkABCDF polycistronic operon, mrkHI bicistronic operon mrkJ gene. MrkH regulatory protein encoded which positively regulates mrkA pilin gene its own expression. In contrast, H-NS nucleoid...

Artificially transforming a scaffold protein into binders often consists of introducing diversity its natural binding region by directed mutagenesis. We have previously developed the archaeal extremophilic Sac7d as to derive affinity reagents (Affitins) randomization only flat surface, or surface and two short loops with lengths. Short are believed contribute stability proteins, loop extension has been reported detrimental for thermal chemical stabilities mesophilic proteins. In this work,...

One promising management strategy for mosquito control is the utilization of a mixture L. sphaericus and B. thuringiensis subsp. israelensis insecticidal toxins. From this set, Bin Cyt1Aa toxins synergize display toxicity to resistant C. quinquefasciatus A. aegypti larvae, whose midgut cells lack toxin receptors. Our data set provides evidence that functional essential internalization or its BinA subunit into such cells, but binding interaction between not observed. Thus, mechanism contrasts...

Pore forming toxins rely on oligomerization for membrane insertion to kill their targets. Bacillus thuringiensis produces insecticidal Cry-proteins composed of three domains that form pores the insect larvae. Domain I is involved in and insertion, whereas Domains II III participate receptor binding specificity. However, structural changes these proteins remain unsolved. The most widely accepted model 'umbrella model', proposed α-4/α-5 hairpin swings away inserted into membrane. To determine...

Bacillus thuringiensis insecticidal Cry toxins break down larval midgut-cells after forming pores. The 3D-structures of Cry4Ba and Cry5Ba revealed a trimeric-oligomer cleavage helices α-1 α-2a, where helix α-3 is extended made contacts with adjacent monomers. Molecular dynamic simulations Cry1Ab-oligomer model based on Cry4Ba-coordinates showed that E101 forms salt-bridge R99 from neighbor monomer. An additional salt bridge was identified in the trimeric-Cry5Ba, located at region...