A novel expression vector for the secretion of abaecin in Bacillus subtilis

ABSTRACT This study aimed to describe a Bacillus subtilis expression system based on genetically modified B. subtilis. Abaecin, an antimicrobial peptide obtained from Apis mellifera, can enhance the effect of pore-forming peptides from other species on the inhibition of bacterial growth. For the exogenous expression, the abaecin gene was fused with a tobacco etch virus protease cleavage site, a promoter Pglv, and a mature beta-glucanase signal peptide. Also, a B. subtilis expression system was constructed. The recombinant abaecin gene was expressed and purified as a recombinant protein in the culture supernatant. The purified abaecin did not inhibit the growth of Escherichia coli strain K88. Cecropin A and hymenoptaecin exhibited potent bactericidal activities at concentrations of 1 and 1.5 µM. Combinatorial assays revealed that cecropin A and hymenoptaecin had sublethal concentrations of 0.3 and 0.5 µM. This potentiating functional interaction represents a promising therapeutic strategy. It provides an opportunity to address the rising threat of multidrug-resistant pathogens that are recalcitrant to conventional antibiotics.

Anticoagulant activity in salivary gland homogenates of Thyrsopelma guianense (Diptera: Simuliidae), the primary vector of onchocerciasis in the Brazilian Amazon

In this study, anticoagulant activity was detected in salivary gland homogenates (SGHs) of Thyrsopelma guianense (Diptera: Simuliidae). The SGH yielded 1.07 ìg ± 0.03 (n = 15) of total soluble protein per pair of glands. In addition, following SDS-PAGE (12.5 percent gel) and silver nitrate staining, 12 polypeptides with molecular weights ranging from 14-69 kDa were detected in all physiological ages analyzed (12 h, 24 h, 48 h and 72 h following emergence). Coagulation bioassays showed that the SGHs had activities that interacted at all levels of coagulation (the intrinsic, extrinsic and common pathways), by extending the plasma recalcification time, prothrombin time, thrombin time. This is the first report on the activity of salivary gland proteins from the main vector of onchocerciasis in Brazil. We also suggest detailed studies on the morphology and function of the salivary glands in order to understand the role of these proteins in host/vector interactions.

Changes of haemolymph protein profile in the larva of Pericallia ricini (Fabricius) parasitised by the Braconid Wasp, Apanteles taragamae Viereck (Hymenoptera: Braconidae).

Parasitism by the braconid wasp, A. taragamae caused alterations in the haemolymph polypeptides of woolly bear larvae of P. ricini. Analysis of haemolymph proteins by SDS-PAGE and densitometry showed that the quantities of haemolymph proteins were reduced dramatically in the parasitised larvae. Simultaneously, parasitism induced large amount of 95 kDa polypeptides in the haemolymph of the parasitised larvae. Also, a remarkable induction of 43 and 45 kDa polypeptides which are not detectable in non-parasitised larvae appeared in the parasitised larvae.

Identification and purification of IgE-reactive proteins in German cockroach extract

Cockroaches have been implicated as a cause of respiratory allergy in urban areas worldwide. IgE-reactive German cockroach proteins were identified with molecular weights (MWs) of 90, 66, 50, 43 and 36 KD by immunoblot analysis in both immune BALB/c mice and sensitized humans. Prominent IgE-reactive proteins were purified using FPLC by ion-exchange chromatography, gel filtration and hydrophobic chromatography. The N-terminal amino acid sequence of a purified protein with a MW of 66 KD on SDS-PAGE was Val-Thr-Leu-Lys-Lys(Val)-Met-Ile-Lys-Thr-Phe-Tyr. No homologous protein was found through a search of GenBank that indicated a novel IgE-reactive protein in German cockroach extract. Another purified protein with a MW of 36 KD reacted strongly with a monoclonal antibody against Bla g 2.