PROTEINS OF THE INTEGUMENTARY SYSTEM OF THE HONEYBEE, Apis mellifera

Abstract

The integument of insects and other arthropods is composed of an inner basal lamina coated by the epidermis, which secretes the bulk of the outer integument layer, the cuticle. The genome sequencing of several insect species has allowed predicting classes of proteins integrating the cuticle. However, only a small proportion of them, as well as other proteins in the integumentary system, have been validated. Using two-dimensional gel electrophoresis coupled with mass spectrometry, we identified 45 different proteins in a total of 112 selected gel spots derived from thoracic integument samples of developing honeybee workers, including 14 cuticular proteins (AmelCPR 3, AmelCPR 12, AmelCPR 16, AmelCPR 27, apidermin 2, apidermin 3, endocuticle structural glycoprotein SgAbd-8-like, LOC100577363, LOC408365, LOC413679, LOC725454, LOC100576916, LOC725838, and peritrophin 3-C analogous). Gene ontology functional analysis revealed that the higher proportions of the identified proteins have molecular functions related to catalytic and structural molecule activities, are involved in metabolic biological processes, and pertain to the protein class of structural or cytoskeletal proteins and hydrolases. It is noteworthy that 26.7% of the identified proteins, including five cuticular proteins, were revealed as protein species resulting from allelic isoforms or derived from posttranslational modifications. Also, 66.7% of the identified cuticular proteins were expressed in more than one developmental phase, thus indicating that they are part of the larval, pupal, and adult cuticle. Our data provide experimental support for predicted honeybee gene products and new information on proteins expressed in the developing integument.

Proteinase pattern of honeybee prepupae from healthy and American Foulbrood infected bees investigated by zymography

“…In our investigation another protein has been detected and identified only in diseased prepupae, the neurofilament heavy polypeptide. This protein has been identified also in pupal integument extract by Micas and Coauthors [54].…”

Hormonal control and target genes of ftz‐f1 expression in the honeybee Apis mellifera: a positive loop linking juvenile hormone, ftz‐f1, and vitellogenin

“…The apidermin gene, apd-3 (NP_001078813.1), was seen to be upregulated by Ftz-F1. Its predicted product shares 40% identity with an Apd-3 form (NP_001167616.1) validated by mass spectrometry of integumentary system proteins (Micas et al, 2016). The predicted translation product of the Ftz-F1-upregulated cuticular gene Glycinerich cell wall structural protein 1.8-like (GeneID 552459) is enriched in GGY and GGYGG repeats, the glycine residues making up 51.2% of one of a series of isoforms (X1 isoform) annotated in the NCBI databank.…”

Comparative Proteomics Studies of Insect Cuticle by Tandem Mass Spectrometry: Application of a Novel Proteomics Approach to the Pea Aphid Cuticular Proteins

“…mellifera pupae (Figure ), among which 22 are defined as CPs by the CutProtFam‐Pred tools, 16 CPR (8 RR‐1 and 8 RR‐2), 2 CPAP3, 2 CPF, and 2 TWDL. The six other proteins have already been described as CPs: two proteins that are not recognized by the CutProtFam‐Pred tool, GB53110 (apidermins‐3) and GB53119 (apidermin‐2). For the other proteins (GB48841, GB48844, GB45151, GB48842), no information about their family is available.…”

“…To date, proteomics studies on cuticular structures have been essentially based on SDS extraction/precipitation, sometimes including a separation by 1D‐ or 2D‐SDS‐PAGE, and subsequent trypsin digestion of the obtained supernatants, gel bands, or SDS‐insoluble pellets prior to structural elucidation by bottom‐up proteomics of the CPs fractions. Such approaches have been used to identify CPs in different species and conditions . In recent studies, between 1100 and 1500 An.…”

“…used a combination of 2D electrophoresis and MALDI‐MS to investigate the proteins present in 15 integuments of Ap. mellifera workers . Even if the approach of electrophoreses is widespread in bottom‐up proteomics, this approach does have limitations because of the number of steps that must be completed, resulting in loss of information.…”