Abstract: Peptidoglycan recognition proteins (PGRPs) are a family of innate immune molecules that recognize bacterial peptidoglycan. PGRP-LE, a member of the PGRP family, selectively binds to diaminopimelic acid (DAP)-type peptidoglycan to activate both the immune deficiency (Imd) and proPhenoloxidase (proPO) pathways in insects. A PGRP-LE-dependent induction of autophagy to control Listeria monocytogenes has also been reported. We identified and partially characterized a novel PGRP-LE homologue, from Tenebrio molitor and analyzed its functional role in the survival of the insect against infection by a DAP-type PGN containing intracellular pathogen, L. monocytogenes. The cDNA is comprised of an open reading frame (ORF) of 990 bp and encodes a polypeptide of 329 residues. TmPGRP-LE contains one PGRP domain, but lacks critical residues for amidase activity. Quantitative RT-PCR analysis showed a broad constitutive expression of the transcript at various stages of development spanning from larva to adult. RNAi mediated knockdown of the transcripts, followed by a challenge with L. monocytogenes, showed a significant reduction in survival rate of the larvae, suggesting a putative role of TmPGRP-LE in sensing and control of L. monocytogenes infection in T. molitor. These results implicate PGRP-LE as a defense protein necessary for survival of T. molitor against infection by L. monocytogenes.
Keywords: peptidoglycan recognition protein; Tenebrio molitor; Listeria monocytogenes; PGRP domain; RNA interference
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Tindwa, H.; Patnaik, B.B.; Kim, D.H.; Mun, S.; Jo, Y.H.; Lee, B.L.; Lee, Y.S.; Kim, N.J.; Han, Y.S. Cloning, Characterization and Effect of TmPGRP-LE Gene Silencing on Survival of Tenebrio Molitor against Listeria monocytogenes Infection. Int. J. Mol. Sci. 2013, 14, 22462-22482.
Tindwa H, Patnaik BB, Kim DH, Mun S, Jo YH, Lee BL, Lee YS, Kim NJ, Han YS. Cloning, Characterization and Effect of TmPGRP-LE Gene Silencing on Survival of Tenebrio Molitor against Listeria monocytogenes Infection. International Journal of Molecular Sciences. 2013; 14(11):22462-22482.
Tindwa, Hamisi; Patnaik, Bharat B.; Kim, Dong H.; Mun, Seulgi; Jo, Yong H.; Lee, Bok L.; Lee, Yong S.; Kim, Nam J.; Han, Yeon S. 2013. "Cloning, Characterization and Effect of TmPGRP-LE Gene Silencing on Survival of Tenebrio Molitor against Listeria monocytogenes Infection." Int. J. Mol. Sci. 14, no. 11: 22462-22482.