earticle

영어

Peptidoglycan (PG) recognition protein (PGRP)-SA and Gram-negative bacteria binding proteins (GNBPs) are suggested to function as lectin-like molecules during Drosophila Toll signaling pathway. However, the molecular mechanisms of how bacterial PG and fungal beta-1,3-glucan recognition signals triggered by PGRP-SA and GNBP molecules are transferred to downstream factors are not clearly determined yet. The elegant Drosophila genetic studies have been and are very powerful for characterizing and arranging the components of the Drosophila Toll pathway. There is a limit with only genetic studies since the mechanisms involved in regulating and controlling this proteolytic cascade have done using a biochemical approach. To identify all essential components necessary for the transferring PGRP-SA or GNBP-mediated recognition signaling pathway, the biochemical approach was performed using the hemolymph of a large beetle, Tenebrio molitor larvae. For the activation of lysine (Lys)-type PG recognition signaling pathway, Lys-type PG/PGRP-SA/GNBP1/modular serine protease (MSP)/ Spätzle processing enzyme activating enzyme (SAE)/Spätzle processing enzyme (SPE)/Spätzle (Spz) cascade is an essential unit that triggers the Lys-type PG recognition signaling pathway in response to Gram-positive bacteria infection. For triggering fungal beta-1,3-glucan recognition signal, beta-1,3-glucan/GNBP3/MSP/SAE/SPE/Spz cascade is enough for transferring beta-1,3-glucan recognition signal in response to fungal infection.. The activation mechanisms of how the PGRP-SA-mediated Lys-type PG recognition signal and of how GNBP3-mediated beta-1,3-glucan recognition signal are transferred to Spz, leading to antimicrobial activity in vivo, is provided. Finally, we purified and determined the whole sequences of the induced antimicrobial peptides after injection of Lys-PG, beta-1,3-glucan, SAE and Spz to the Tenebrio larvae. Our data provides the first biochemical evidences of how the PGRP-SA-mediated Lys -type PG recognition signal and GNBP3-mediated beta-1,3-glucan recognition signal are transferred to Spätzle via PGRP-SA and GNBPs, leading to antimicrobial activities in vivo.