|Tereshchenkova, Valeriia - Moscow State University|
|Goptar, Irina - Moscow State University|
|Kulemzina, Irina - Moscow State University|
|Zhuzhikov, Dmitry - Moscow State University|
|Serebryakova, Marina - Moscow State University|
|Belozersky, Mikahil - Moscow State University|
|Dunaevsky, Yakov - Moscow State University|
|Filippova, Irina Yu. - Moscow State University|
|Elpidina, Elena - Moscow State University|
Submitted to: Insect Biochemistry and Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/5/2016
Publication Date: 9/15/2016
Publication URL: https://handle.nal.usda.gov/10113/5244986
Citation: Tereshchenkova, V.F., Goptar, I.A., Kulemzina, I.A., Zhuzhikov, D.P., Serebryakova, M.V., Belozersky, M.A., Dunaevsky, Y.E., Oppert, B.S., Filippova, I., Elpidina, E.N. 2016. Dipeptidyl peptidase 4 – an important digestive peptidase in Tenebrio molitor larvae. Insect Biochemistry and Molecular Biology. 76:38-48. doi:10.1016/j.ibmb.2016.07.003.
Interpretive Summary: Stored product insects, such as the yellow mealworm, have evolved specialized enzymes to digest proteins such as gliadins, a component of gluten, found in their food. In this report, we detail the first description of one of these enzymes, called dipeptidyl peptidase 4. These enzymes are found in humans and other mammals, where they are found in the membrane of tissues and they perform various biological functions. However, in insects, the enzyme is not in the membrane but instead is found in solution, and has apparently evolved to specifically digest gliadins. We provide specific details about the enzyme and compare it to the mammalian enzyme. This study is the latest in a series of articles from our laboratories to detail how specific enzymes in beetles have adapted to more efficiently digest specific foods, providing more information that can contribute to the development of new types of control strategies targeting their digestion of food.
Technical Abstract: Dipeptidyl peptidase 4 (DPP 4) is a proline specific serine peptidase that plays an important role in different regulatory processes in mammals. In this report, we isolated and characterized a unique secreted digestive DPP 4 from the anterior midgut of a stored product pest, Tenebrio molitor larvae (TmDPP 4), with a biological function different than that of the well-studied mammalian DPP 4. The sequence of the purified enzyme was confirmed by mass-spectrometry, and was identical to the translated RNA sequence found in a gut EST database. The purified peptidase was characterized according to its localization in the midgut, and substrate specificity and inhibitor sensitivity were compared with those of human recombinant DPP 4 (rhDPP 4). The T. molitor enzyme was localized mainly in the anterior midgut of the larvae, and 81% of the activity was found in the fraction of soluble gut contents, while human DPP 4 is a membrane enzyme. TmDPP 4 was stable in the pH range 5.0-9.0, with an optimum activity at pH 7.9, similar to human DPP 4. Only specific inhibitors of serine peptidases, diisopropyl fluorophosphate and phenylmethylsulfonyl fluoride, suppressed TmDPP 4 activity, and the specific dipeptidyl peptidase inhibitor vildagliptin was most potent. The highest rate of TmDPP 4 hydrolysis was found for the synthetic substrate Arg-Pro-pNA, while Ala-Pro-pNA was a better substrate for rhDPP 4. Related to its function in the insect midgut, TmDPP 4 efficiently hydrolyzed the wheat storage proteins gliadins, which are major dietary proteins of T. molitor.