Comparative Proteomics Reveal Diverse Functions and Dynamic Changes of Bombyx mori Silk Proteins Spun from Different Development Stages

Abstract

Silkworms (Bombyx mori) produce massive amounts of silk proteins to make cocoons during the final stages of larval development. Although the major components, fibroin and sericin, have been the focus for a long time, few researchers have realized the complexity of the silk proteome. We collected seven kinds of silk fibers spun by silkworm larvae at different developmental stages: the silks spun by new hatched larvae, second instar day 0 larvae, third instar day 0 larvae, fourth instar day 0 larvae, and fourth instar molting larvae, the scaffold silk used to attach the cocoon to the substrate and the cocoon silk. Analysis by liquid chromatography-tandem mass spectrometry identified 500 proteins from the seven silks. In addition to the expected fibroins, sericins, and some known protease inhibitors, we also identified further protease inhibitors, enzymes, proteins of unknown function, and other proteins. Unsurprisingly, our quantitative results showed fibroins and sericins were the most abundant proteins in all seven silks. Except for fibroins and sericins, protease inhibitors, enzymes, and proteins of unknown function were more abundant than other proteins. We found significant change in silk protein compositions through development, being consistent with their different biological functions and complicated formation.

Comparative proteomic analysis of silkworm fat body after knocking out fibroin heavy chain gene: a novel insight into cross-talk between tissues

“…Furthermore, to analyze the abundances of proteins from each functional category in different samples, the percentages of proteins based on relative mass abundances were used. Relative mass abundances were calculated by protein iBAQ abundance×molecular mass (Dong et al 2013). In contrast, to compare the abundances of proteins across different samples, we used the LFQ algorithm, which compares the intensity of the same protein in different samples (Luber et al 2010).…”

“…It has been known that silk proteins are mainly composed of fibroins and sericins (Dong et al 2013;Gamo et al 1977), and fibroins consist of fibroin heavy chain (Fib-H), fibroin light chain (Fib-L), and P25 with a 6:6:1 molar ratio (Inoue et al 2000). The silkworm fibroin heavy chain gene (BmFib-H) is specifically expressed in the silk gland, which is reported to be closely related to silk production.…”

Rheological behaviour of native silk feedstocks

“…The larvae of various lepidoptera (i.e. caterpillars) appear to produce only one type of silk at any time, although the quantities and compositions vary between species [5] and developmental stage [12]. Most notably, as a result of millennia of selective human intervention, the domesticated mulberry silkworm Bombyx mori, produces relatively large quantities of cocoon silk, which has achieved considerable importance as a textile fibre [13e16].…”

Silk Fibers as Smart Materials Toward Medical Textiles

“…Usually sericin protein is removed by a degumming process (usually boiling in alkaline solutions) to produce textile fiber. Recently, the presence of many proteins aside from fibroin and sericin was reported from results of proteome analysis [8]. Fibroin, which is synthesized at the posterior silk gland, consists of complexes including 350 kDa heavy chains, 25 kDa light chains, and fibrohexamerin/P25.…”