Simona Laurino

Extracellular matrix degradation via enolase/plasminogen interaction: Evidence for a mechanism conserved in Metazoa

While enolase is a ubiquitous metalloenzyme involved in the glycolytic pathway, it is also known as a multifunctional protein, since enolases anchored on the outer surface of the plasma membrane are involved in tissue invasion.

Identification of major Toxoneuron nigriceps venom proteins using an integrated transcriptomic/proteomic approach.

Endoparasitoids in the order Hymenoptera are natural enemies of several herbivorous insect pest species. During oviposition they inject a mixture of factors, which include venom, into the host, ensuring the successful parasitism and the development of their progeny. Although these parasitoid factors are known to be responsible for host manipulation, such as immune system suppression, little is known about both identity and function of the majority of their venom components. To identify the major proteins of Toxoneuron nigriceps (Hymenoptera: Braconidae) venom, we used an integrated transcriptomic and proteomic approach. The tandem-mass spectrometric (LC-MS/MS) data combined with T. nigriceps venom gland transcriptome used as a reference database resulted in the identification of a total of thirty one different proteins. While some of the identified proteins have been described in venom from several parasitoids, others were identified for the first time. Among the identified proteins, hydrolases constituted the most abundant family followed by transferases, oxidoreductases, ligases, lyases and isomerases. The hydrolases identified in the T. nigriceps venom glands included proteases, peptidases and glycosidases, reported as common components of venom from several parasitoid species. Taken together, the identified proteins included factors that could potentially inhibit the host immune system, manipulate host physiological processes and host development, as well as provide nutrients to the parasitoid progeny, degrading host tissues by specific hydrolytic enzymes. The venom decoding provides us with information about the identity of candidate venom factors which could contribute to the success of parasitism, together with other maternal and embryonic factors.

Identification of two arginine kinase forms of endoparasitoid Leptomastix dactylopii venom by bottom up-sequence tag approach.

Leptomastix dactylopii (Howard) is an endoparasitoid wasp, natural enemy of mealybug Planococcus citri (Risso). Despite the acquired knowledge regarding this host-parasitoid interaction, only little information is available on the factors of parasitoid origin able to modulate the mealybug physiology. The major alteration observed in P. citri is a strong reduction in fecundity, which is evident soon after parasitization by L. dactylopii or venom injection in unparasitized hosts indicating that this proteinaceus secretion injected at the oviposition plays a key-role in host regulation. Protein identification of L. dactilopii venom has been limited by the lack of literature sources and public protein databases. Here, we identified two venom proteins by an integrated trascriptomic and proteomic approach. A custom-made transcriptomic database from the L. dactylopii venom glands was created by applying the high-throughput RNA sequencing approach. Two-dimensional gel electrophoresis (2DE) trypsinized protein spots were analyzed by high-resolution mass spectrometry (FTICRMS-12 T). The most abundant peptide ions were fragmented by collision induced dissociation and the obtained sequence tags were subjected to custom-made protein database searching. Two putative arginine kinases (full-length and truncated form) were identified. This is the first case in which both, truncated and full length arginine kinases, are identified in an endoparasitoid non-paralyzing venom.

The Lepidopteran endoribonuclease-U domain protein P102 displays dramatically reduced enzymatic activity and forms functional amyloids.

Abstract Hemocytes of Heliothis virescens (F.) (Lepidoptera, Noctuidae) larvae produce a protein, P102, with a putative endoribonuclease-U domain. In previous works we have shown that P102 is involved in Lepidopteran immune response by forming amyloid fibrils, which catalyze and localize melanin deposition around non-self intruders during encapsulation, preventing harmful systemic spreading. Here we demonstrate that P102 belongs to a new class of proteins that, at least in Lepidoptera, has a diminished endoribonuclease-U activity probably due to the lack of two out of five catalytically essential residues. We show that the P102 homolog from Trichoplusia ni (Lepidoptera, Noctuidae) displays catalytic site residues identical to P102, a residual endoribonuclease-U activity and the ability to form functional amyloids. On the basis of these results as well as sequence and structural analyses, we hypothesize that all the Lepidoptera endoribonuclease-U orthologs with catalytic site residues identical to P102 form a subfamily with similar function.