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Publication Abstract from PubMed

LaIT2, composed of 59 amino acid residues, is a peptide toxin isolated from the venom of the Yaeyama scorpion, Liocheles australasiae. LaIT2 is toxic to insects but not most mammals. The N- and C-domains of LaIT2 are known to possess antimicrobial and insecticidal activities, respectively. However, the molecular mechanisms are largely unknown because of the lack of a three-dimensional structure of LaIT2. Thus, we elucidated the solution NMR structure of LaIT2. LaIT2 adopts a beta-KTx-like two-domain structure, in which the N- and C-terminal domains form a random coil and an alpha-beta-beta motif, respectively. Trifluoro ethanol and liposomes titration experiments showed that the unstructured N-domain of LaIT2 has the ability to form an alpha-helix. The N-terminal helix is amphiphilic, and one side of the helix is positively charged. Measurements of the antimicrobial and insecticidal activities of LaIT2 mutants suggested K15 in the N-domain was found to be responsible for the antimicrobial activities, whereas L53 and L54 in the C-domain were key residues involved in the insecticidal activity. Moreover, K21 in the N-domain is important for both activities. Therefore, two domains are suggested that they work together to show antimicrobial and insecticidal activity.

Structural and functional studies of LaIT2, an antimicrobial and insecticidal peptide from Liocheles australasiae.,Tamura M, Tatsushiro C, Morita EH, Ohki S Toxicon. 2022 Jul 30;214:8-17. doi: 10.1016/j.toxicon.2022.04.015. Epub 2022 Apr , 29. PMID:35490851^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.