Molecular and structural characterization of proline-rich peptides in Apis mellifera to Leptospira interrogans: Exploring potential therapeutic applications of Apidaecin to LipL32

Document Type : Original Article

Authors

Department of Medical Technology, Institute of Health Sciences and Nursing, Far Eastern University – Manila, Nicanor Reyes St., Sampaloc, Manila, Metro Manila, Philippines.

Abstract

Leptospirosis is a disease caused by the gram-negative bacterium Leptospira interrogans, with limited treatments contributing to its growing global burden. This study investigates Apidaecin, a proline-rich antimicrobial peptide (PRAMP) from Apis mellifera (honeybee), targeting LipL32, a key virulence factor of Leptospira interrogans. Using an in-silico approach, ProtParam analyzed Apidaecin's molecular characteristics. Notably, theoretical isoelectric point, instability index, aliphatic index, and hydropathicity were 10.95, 81.52, 46.63, and -1.717, respectively. Furthermore, AlphaFold Protein Structure Database generated the three-dimensional structures of the proteins, and molecular docking via LZerD Protein Web Server identified Model 1 as the most favorable binding interaction, attaining a Ranksum score of 42, and consistent ranks of 14 in GOAP, DFIRE, and ITScore. Model 2 follows with a score of 64 and Model 3 scores 77. Models 4 and 5 perform poorly, with Ranksum score of 150 and 157, mainly due to high GOAP ranks of 137 and 92, respectively. Results also suggest that Apidaecin's high proline content (28.1%) enhances its bacteriostatic activity via ribosomal restraining capacity to inhibit elongation of protein. This structural property allows Apidaecin to target gram-negative bacteria without damaging the host membrane, making it a promising therapeutic candidate. Moreover, the nature of the findings stems primarily from computational predictions, providing valuable preliminary insights. Thus, these in silico findings require further experimental validation, particularly in vitro assays, in vivo studies, and clinical evaluations, to assess its pharmacokinetics, efficacy, and safety for human use.

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