Complex of Proline-Specific Peptidases in the Genome and Gut Transcriptomes of Tenebrionidae Insects and Their Role in Gliadin Hydrolysis.

A detailed analysis of the complexes of proline-specific peptidases (PSPs) in the midgut transcriptomes of the larvae of agricultural pests Tenebrio molitor and Tribolium castaneum and in the genome of T. castaneum is presented. Analysis of the T. castaneum genome revealed 13 PSP sequences from the clans of serine and metal-dependent peptidases, of which 11 sequences were also found in the gut transcriptomes of both tenebrionid species' larvae. Studies of the localization of PSPs, evaluation of the expression level of their genes in gut transcriptomes, and prediction of the presence of signal peptides determining secretory pathways made it possible to propose a set of peptidases that can directly participate in the hydrolysis of food proteins in the larvae guts. The discovered digestive PSPs of tenebrionids in combination with the post-glutamine cleaving cysteine cathepsins of these insects effectively hydrolyzed gliadins, which are the natural food substrates of the studied pests. Based on the data obtained, a hypothetical scheme for the complete hydrolysis of immunogenic gliadin peptides by T. molitor and T. castaneum digestive peptidases was proposed. These results show promise regarding the development of a drug based on tenebrionid digestive enzymes for the enzymatic therapy of celiac disease and gluten intolerance.

Significant Hydrolysis of Wheat Gliadin by Bacillus tequilensis (10bT/HQ223107): a Pilot Study.

Peptidase therapy is suggested to be effective to minimize gliadin toxicity in celiac disease (CD). Hence, present study deals with gliadin-hydrolysing peptidases. The efficient peptidase from the Bacillus tequilensis was purified using ammonium sulfate fractionation and preparative electrophoresis. Analysis of in-solution and in-gel hydrolysis of gliadin using one and two-dimensional SDS-PAGE revealed nearly complete hydrolysis of gliadin peptides after 180 min of incubation with B. tequilensis protease. Purified peptidase was found to be stable at acidic (pH 3.5) to neutral (pH 7.2) pH range. The molecular mass and isoelectric point of the peptidase were observed around 29 kDa and 5.2, respectively. The internal protein sequence obtained through mass spectrometric analysis suggested that peptidase might belong to peptidase S9 family known for prolyl-specific peptidases. This study recommends the possible applicability of this peptidase for elimination of immunotoxic gliadin peptides and may prove useful in CD treatment.