Proteomic analyses of venom from a Spider Hawk, Pepsis decorata

Abstract

Background: The composition of the venom from solitary wasps is poorly known, although these animals are considered sources of bioactive substances. Until the present moment, there is only one proteomic characterization of the venom of wasps of the family Pompilidae and this is the first proteomic characterization for the genus Pepsis.

Methods: To elucidate the components of Pepsis decorata venom, the present work sought to identify proteins using four different experimental conditions, namely: (A) crude venom; (B) reduced and alkylated venom; (C) trypsin-digested reduced and alkylated venom, and; (D) chymotrypsin-digested reduced and alkylated venom. Furthermore, three different mass spectrometers were used (Ion Trap-Time of Flight, Quadrupole-Time of Flight, and Linear Triple Quadruple).

Results: Proteomics analysis revealed the existence of different enzymes related to the insect's physiology in the venom composition. Besides toxins, angiotensin-converting enzyme (ACE), hyaluronidase, and Kunitz-type inhibitors were also identified.

Conclusion: The data showed that the venom of Pepsis decorata is mostly composed of proteins involved in the metabolism of arthropods, as occurs in parasitic wasps, although some classical toxins were recorded, and among them, for the first time, ACE was found in the venom of solitary wasps. This integrative approach expanded the range of compounds identified in protein analyses, proving to be efficient in the proteomic characterization of little-known species. It is our understanding that the current work will provide a solid base for future studies dealing with other Hymenoptera venoms.

Keywords: Wasp; proteins; solitary wasp; toxins; venomics.

Figure 1.. (A) Female Pepsis decorata feeding on pollen from a Mimosoideae plant. One can notice the spots on the wings and the bluish-black coloration. (B) Female Pepsis decorata in captivity feeding on a mixture of honey, sucrose, and water.

Figure 2.. Molecular function keyword¹ percentage distribution of the proteomic² identified proteins present in the Pepsis decorata crude venom, as analyzed by the IT-TOF mass spectrometer. ¹ According to the Gene Ontology (GO) project. ² The proteomic identification was performed on the reduced, alkylated, and trypsin-digested crude venom. Color code: (Gray) uncharacterized proteins; (Green) Proteins with GO annotation. (Blue) Ribonucleproteins; (Red) Hydrolases; (Orange) tranferase; (Yellow) Oxidoreductases; (Light blue) others.

Figure 3.. Molecular function keyword¹ percentage distribution of the proteomic² identified proteins present in the Pepsis decorata crude venom, as analyzed by the LTQ mass spectrometer. ¹ According to the Gene Ontology (GO) project. ² The proteomic identification was performed on the reduced, alkylated, and trypsin-digested crude venom. Color code: Gray: uncharacterized proteins; Green: Proteins with GO annotation. Blue: Ribonucleoproteins; Red: Hydrolases; Orange: transferase; Yellow: Oxidoreductases; Light blue: others; Pink: Venom-related molecules (antimicrobial).

Figure 4.. Molecular function keyword¹ percentage distribution of the proteomic² identified proteins present in the Pepsis decorata crude venom, as analyzed by the Q-TOF mass spectrometer. ¹ According to the Gene Ontology (GO) project. ² The proteomic identification was performed on the reduced, alkylated, and trypsin-digested crude venom. Color code: (Gray) uncharacterized proteins; (Green) Proteins with GO annotation. (Red) Hydrolases; (Yellow) Oxidoreductases; (Light blue) others; (Pink) Venom-related molecules (toxins and protease inhibitors).