Two Tachykinin-Related Peptides with Antimicrobial Activity Isolatedfrom Triatoma infestans Hemolymph

摘要

Antimicrobial peptides and proteins (AMPs) are molecules that can interact withmicrobial cells and lead to membrane disruption or intracellular moleculeinteractions and death. Several molecules with antimicrobial effects alsopresent other biological activities. One such protein group representing theduplicity of activities is the tachykinin family. Tachykinins (TKs) form afamily of neuropeptides in vertebrates with a consensus C-terminal region(F-X-G-Y-R-NH2). Invertebrate TKs and TK-related peptides (TKRPs) aresubfamilies found in invertebrates that present high homology with TKs and havesimilar biological effects. Several of these molecules have already beendescribed but reports of TKRP in Hemiptera species are limited. By analyzing theTriatoma infestans hemolymph by reversed-phasehigh-performance liquid chromatography, biological assays, and massspectrometry, two antimicrobial molecules were isolated and identified as TKRPs,which we named as TRP1-TINF and TRP2-TINF (tachykinin-related peptides I and IIfrom T. infestans). TRP1-TINF is a random secondary structurepeptide with 9 amino acid residues. It is susceptible to aminopeptidasesdegradation and is active mainly against Micrococcus luteus (32μM). TRP2-TINF is a 10-amino acid peptide with a 310 helix secondary structureand is susceptible to carboxypeptidases degradation. It has major antimicrobialactivity against both Pseudomonas aeruginosa andEscherichia coli (45 μM). Neither molecule is toxic tohuman erythrocytes and both present minor toxicity toward Vero cells at aconcentration of 1000 μM. As the first description of TKRPs with antimicrobialactivity in T. infestans, this work contributes to the widercomprehension of the insects’ physiology and describes pharmacological relevantmolecules.