Structural cuticular proteins from arthropods: Annotation, nomenclature, and sequence characteristics in the genomics era

Abstract

The availability of whole genome sequences of several arthropods has provided new insights into structural cuticular proteins (CPs), in particular the distribution of different families, the recognition that these proteins may comprise almost 2% of the protein coding genes of some species, and the identification of features that should aid in the annotation of new genomes and EST libraries as they become available. Twelve CP families are described: CPR (named after the Rebers and Riddiford Consensus); CPF (named because it has a highly conserved region consisting of about forty-four amino acids); CPFL (like the CPFs in a conserved C-terminal region); the TWDL family, named after a picturesque phenotype of one mutant member; four families in addition to TWDL with a preponderance of low complexity sequence that are not member of the families listed above. These were named after particular diagnostic features as CPLCA, CPLCG, CPLCW, CPLCP. There are also CPG, a lepidopteran family with an abundance of glycines, the apidermin family, named after three proteins in Apis mellifera, and CPAP1 and CPAP3, named because they have features analogous to peritrophins, namely one or three chitin-binding domains.Also described are common motifs and features. Four unusual CPs are discussed in detail. Data that facilitated the analysis of sequence variation of single CP genes in natural populations are analyzed.

Mutation of a Cuticular Protein,BmorCPR2, Alters Larval Body Shape and Adaptability in Silkworm,Bombyx mori

“…Meanwhile, mass spectrometry results revealed that the electrophoretic bands contain BmorCPR2, validating the capacity of BmorCPR2 to bind chitin ( Figure 4, B and C, and Table S2). These findings are consistent with the structural characteristics of the protein and results of Tang et al (Rebers and Riddiford 1988;Futahashi et al 2008;Willis 2010;Andersen 2011). Subsequently, we assayed the chitin content of Dazao and Dazao-stony larval cuticles (day 5 of the fifth instar).…”

“…We analyzed the upstream and downstream sequences of S0 in the silkworm database. Close to the S0 marker, we observed two predicted gene models encoding RR1-type chitin-binding cuticular proteins that play an important role in construction of the soft insect cuticle (Andersen et al 1995(Andersen et al , 2011Togawa et al 2008;Moussian 2010;Willis 2010) (Figure 2A-iii). Full-length cDNA of BGIBMGA005278 (BmorCPR3) was not different in wild type and stony, and the gene expression patterns were relatively similar (Figure 2A-v, and Figure S2).…”

“…CP-chitin interactions are necessary for the normal structure and physical properties of cuticle (Andersen et al 1995;Rebers and Willis 2001;Karouzou et al 2007;Cornman et al 2008;Moussian 2010). Over half of the known cuticular proteins contain chitin-binding domains, including the Rebers & Riddiford (R&R) motif (two major groups, RR-1 and RR-2, and a minor form, RR-3), Tweedle motif, and chtDB2 domain (Rebers and Riddiford 1988;Magkrioti et al 2004;Cornman et al 2008;Jasrapuria et al 2010;Willis 2010;Andersen 2011;Gilbert 2011, Chap. 5).…”

Two major cuticular proteins are required for assembly of horizontal laminae and vertical pore canals in rigid cuticle of Tribolium castaneum

“…Many of the insect structural CPs have been classified into 12 different families as defined by unique amino acid sequence motifs characteristic of each of the families (Willis, 2010;Ioannidou et al, 2014). The largest family is the CPR family whose members contain the Rebers & Riddiford (R&R) Consensus (Rebers and Riddiford, 1988).…”

“…CPR proteins containing the RR-1 motif have been found primarily in soft and flexible cuticles, while proteins with the RR-2 motif have been found mostly in rigid cuticles (Willis et al, 2005). CPR proteins with the RR-3 motif have been identified only in a few species (Andersen, 2000;Futahashi et al, 2008;Willis, 2010). Transcriptional regulation of CP gene expression appears to be regulated by developmental and hormonal cues (Ali et al, 2013;Charles, 2010).…”