The Evolution, Gene Expression Profile, and Secretion of Digestive Peptidases in Lepidoptera Species

Abstract

Serine peptidases (SPs) are responsible for most primary protein digestion in Lepidoptera species. An expansion of the number of genes encoding trypsin and chymotrypsin enzymes and the ability to upregulate the expression of some of these genes in response to peptidase inhibitor (PI) ingestion have been associated with the adaptation of Noctuidae moths to herbivory. To investigate whether these gene family expansion events are common to other Lepidoptera groups, we searched for all genes encoding putative trypsin and chymotrypsin enzymes in 23 publicly available genomes from this taxon. Phylogenetic analysis showed that several gene family expansion events may have occurred in the taxon’s evolutionary history and that these events gave rise to a very diverse group of enzymes, including proteins lacking the canonical SP catalytic triad. The expression profile of these enzymes along the midgut and the secretion mechanisms by which these enzymes enter the luminal content were also analyzed in Spodoptera frugiperda larvae using RNA-seq and proteomics. These results support the proposal of a midgut countercurrent flux responsible for the direction of these proteins to the anterior portion of the midgut and show that these enzymes reach the midgut lumen via both exocytosis and microapocrine secretion mechanisms.

A soybean trypsin inhibitor reduces the resistance to transgenic maize in a population of Spodoptera frugiperda (Lepidoptera: Noctuidae)

“…Similar to that observed here for the Bt maize-resistant S. frugiperda population, Helicoverpa armigera (Hübner, [1808]) (Lepidoptera: Noctuidae) presented reduced growth and survival rates when ingesting an artificial diet containing Cry1Ac combined with a trypsin inhibitor ( Lomate and Hivrale 2013 ). Trypsins are key proteases involved in Lepidopteran larval digestion, having a significant role in primary digestion of proteins ( Srinivasan et al 2006 , Lima et al 2020 ). Blocking trypsin activity using trypsin inhibitors, such as SBTI, may result in negative effects on amino acid nutrition and, consequently, in insect development ( Macedo et al 2010 , Macedo and Freire 2011 , Zhu-Salzman and Zeng 2015 , Meriño-Cabrera et al 2020 ).…”

Intestinal proteases profiling from Anticarsia gemmatalis and their binding to inhibitors

“…But what appears to be a fact is that the great diversity of isoforms is important not only to deal with the diverse content of plant proteins but also to circumvent an expressive part of the PI‐based plant defense. Lima et al (2020) reported that approximately one‐third of the proteases expressed in the intestine of insects of the order Lepidoptera correspond to serine proteases (EC 3.4.16 and EC 3.4.21). This fraction of enzymes can represent up to 95% of the proteolytic activity in the larval intestine in lepidopteran (Srinivasan et al, 2006).…”

Adaptation of Helicoverpa armigera to Soybean Peptidase Inhibitors Is Associated with the Transgenerational Upregulation of Serine Peptidases

“…Serine peptidase genes present in the H. armigera genome were identified using the BLASTP program with a set of well-described SP genes as the query [5]. The identified sequences were then filtered using the presence of a predicted trypsin domain (IPR001254) according to an InterproScan analysis and a complete catalytic triad (His57, Asp102, and Ser195) [61]. Subsequently, trypsin and chymotrypsin genes were classified according to the amino acid at position 189 (Asp for trypsin).…”