In silico identification, characterization and expression analysis of attacin gene family in response to bacterial and fungal pathogens in Tenebrio molitor

Abstract

Antimicrobial peptides are effector molecules induced after microbial challenges. These form important components of innate host defense against the pathogens by exhibiting wide-spectrum antimicrobial activities. In this study, we identified three attacin-like genes from Tenebrio molitor RNASeq database using Tribolium castaneum attacin gene family as query. The T. molitor attacin gene family was annotated as TmAttacin-1a [comprising of 154 amino acids (aa)], TmAttacin-1b (150 aa) and TmAttacin-2 (164 aa), respectively. Temporal expression analysis shows that the TmAttacin-1a and -1b mRNAs are highly expressed in late larval stages, followed by a general decline in the pre-pupal stages. The mRNA level shows a decline during metamorphosis, and gets slightly overexpressed in pupal-adult transition stages. On the other hand, TmAttacin-2 is mainly overexpressed at 1-day old pupal stage. Spatial expression analysis indicates that TmAttacin-1a, À1b, and À2 mRNAs are primarily expressed in gut and fat body, but not in hemocytes and Malpighian tubules in T. molitor larvae. Interestingly, TmAttacin-1b shows more than 20-fold expression in the ovary, whereas TmAttacin-1a and À2 show similar expression patterns in gut, fat body, hemocyte, ovary, and testis in T. molitor adults. Induction pattern analysis demonstrates that the intracellular Gram-positive bacteria, L. monocytogenes elicited the strongest response by inducing~1,000-fold expression of TmAttacin-1a mRNA. The highest level of TmAttacin-1b mRNA (~350-fold) was induced by Gram-negative bacteria, E. coli. However, the TmAttacin-2 transcripts were not induced by microbial challenges. These results indicate that TmAttacin-1a and -1b may be required for antimicrobial defenses in T. molitor.

TmRelish is required for regulating the antimicrobial responses to Escherichia coli and Staphylococcus aureus in Tenebrio molitor

“…In order to determine whether TmRelish knockdown affected AMP regulation, the expression profile of fourteen AMPs including members of the Tenecin family (TmTenecin-1 (TmTene1), TmTene2, TmTene3, and TmTene4) [29][30][31][32] ; Attacin family (TmAttacin-1a (TmAtta1a), TmAtta1b, and TmAtta2) 33 ; TmDefensin-1 (TmDef1); TmDef2; TmColeptericin-1 (TmCole1); TmCole2; TmCecropin-2 (TmCec2); and thaumatin-like protein (TmTLP1 and TmTLP2) 34,35 was examined in TmRelish-silenced T. molitor larvae following microbial challenge. The immune tissues of the insect (fat body, hemocytes, gut, and MTs) were dissected 24 h post microbial challenge.…”

TmSpz6 Is Essential for Regulating the Immune Response to Escherichia coli and Staphylococcus aureus Infection in Tenebrio molitor

“…The results reveal that TmSpz6 silencing suppressed the induction of several AMP gene expressions in response to microbial infection, supporting the survival study results. Most of the AMP genes that were suppressed when TmSpz6 was silenced encode AMPs that have activity against gram-negative bacteria, such as E. coli (Tene-2, Cec-2, Tene-4, and Cole-1) [24,[47][48][49][50], and gram-positive bacteria, such as S. aureus (Tene-3, Def-1, Def-2, Cec-2 and Tene-1) [51][52][53][54].…”

TmSpz4 Plays an Important Role in Regulating the Production of Antimicrobial Peptides in Response to Escherichia coli and Candida albicans Infections

“…These suppressed AMPs have been shown to have antibacterial activity against both gram-negative bacteria and fungi [39][40][41][42]. In particular, glycine-rich AMPs, such as attacins, in Hyalophora cecropia [43] and T. molitor [44], as well as tenecin-2 and -4 in T. molitor [30,45] have been shown to be particularly effective against Gram-negative bacteria. The effectiveness of tenecin-3 [46], tenecin-1, tenecin-2 [47], and defensins [48] against fungal infections has also been reported.…”