Expression profiling, phylogenetic, and structural analyses of a laccase gene from the red palm weevil, Rhynchophorus ferrugineus

Abstract

Laccases, member of multicopper oxidase (MCO) family enzymes, play crucial roles in insects' cuticle tanning and pigmentation. The purpose of this study was to identify and characterize a laccase gene from the red palm weevil (RPW), Rhynchophorus ferrugineus. The isolated RPW laccase gene sequence was 3,389 bp, including a 2,163 bp open reading frame that encodes 720 amino acids. The RPW laccase gene conserved the MCO functional motifs Type-3, Type-1, and Type-2, respectively. Phylogenetic analysis categorized this protein into the functional cluster 2 of insect laccases (Lac2). The primary transcripts for R. ferrugineus laccase 2 (RfeLac2) were highly expressed in the adult's cuticle, elytra, and hindwings, and in the larval cuticles four days before molting. Then, the transcripts were declined drastically in the larval cuticles three days before molting. This implies that the suppression of RfeLac2 in the larvae occurs earlier than expected. RfeLac2 transcripts were very low in the gut and adipose tissues of larvae and adults, irrespective to the span to undergo molting. This suggests that RfeLac2 is not active in the tissues that do not undergo heavy sclerotization. Three-dimensional (3-D) structure modeling of RfeLac2 predicted eight histidines, one glycine, and one phenylalanine, as copper-binding ligands on the laccase active center. The study finding indicates that the pattern of the RPW RfeLac2 expression varies from other coleopteran insects, a phenomenon that requires further investigation.

A Review on Digestive System of Rhynchophorus ferrugineus as Potential Target to Develop Control Strategies

“…In addition, the transcript of a laccase enzyme (EC: 1.10.3.2) was found to be expressed in the gut of RPW ( Table 2 ). This enzyme is a cuticular protein responsible for cuticle hardening to protect insects from environmental stress, and it may oxidize toxic compounds ingested by insects [ 81 ]. The injection of dsRNA into Tribolium castaneum designed for an RNAi experiment resulted in the depletion of laccase transcripts and caused the weevils to fail to tan, producing soft-bodied weevils that subsequently died [ 82 , 83 ].…”

“…To regulate physiology and behavior of insects [90] Not tested Laccase Oxidize toxic compounds ingested by the insect [81] Not tested Xylanase Digestion of plant cell wall [53] Not tested Aminopeptidase Protein digestion [20] Not tested Cellulase Digestion of plant cell wall [88] Not tested Pectinase Digestion of plant cell walls [88,92] Not tested Glucosidase Carbohydrate digestion [56] According to Zulkifli et al [20], among the alternative methods in managing RPW infestations is targeting the potential proteins involved in nutrition or digestion. Identifying selective inhibitors of the digestive enzymes and potentially targeted proteins or genes in the RPW gut is important to turn off the enzymatic activity.…”

Functionalization of MWCNTs for Bioelectrocatalysis by Bacterial Two-Domain Laccase from Catenuloplanes japonicus

“…Based on their spectroscopic features, copper sites can be divided into three categories reflecting the electronic and geometric structure of the active site: type 1 (T1) or blue copper, type 2 (T2) or normal copper, and type 3 (T3) or coupled binuclear copper centers [32]. Most laccases found in fungi, plants, and insects, contain Nanomaterials 2023, 13, 3019 3 of 24 three cupredoxin domains (T1, T2, and T3), and they are able to function in the monomeric form [33][34][35].…”