Fiber Formation and Mechanical Properties of Bombyx mori Silk Are Regulated by Vacuolar-Type ATPase

Abstract

The mechanism of silk fiber formation in silkworms, Bombyx mori, is of particular scientific interest because it is closely related to the mechanical properties of silk fibers. However, there are still substantial knowledge gaps in understanding the details of this mechanism. Studies have found a pH gradient in the silk gland of silkworms. A vacuolar-type ATPase (V-ATPase) is thought to be involved in establishing this pH gradient. Although it is reported that the pH gradient plays a role in silk fibrillogenesis, the direct relationship between V-ATPase and silk mechanical properties is unclear. Thus, this study aims to clarify this relationship. We found that V-ATPase is highly and stably expressed in the anterior silk gland (ASG) and maintains the pH gradient and the fine structure of ASG. Inhibition of V-ATPase activity increased the β-sheet content and crystallinity of silk fibers. Tensile testing showed that the mechanical properties of silk fibers improved after inhibiting V-ATPase activity. All the data suggest that V-ATPase is a key factor in regulating silk fibrillogenesis and is related to the final mechanical properties of the silk fibers. V-ATPase is a potential target for silk mechanical property improvement.

A molecular atlas reveals the tri-sectional spinning mechanism of spider dragline silk

“…5g ; Supplementary Data 20 ). Interestingly, we found that seven ortholog gene pairs involved in the V-type ATPase family, encoding key factors involved in regulating silk fibrillogenesis 52 , were significantly upregulated in both the Duct and ASG (Fig. 5g ).…”

The silk gland proteome of Stenopsyche angustata provides insights into the underwater silk secretion

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Molecular atlas reveals the tri-sectional spinning mechanism of spider dragline silk

“…5g; Supplementary Table 20). Interestingly, we found that seven gene ortholog pairs involved in the V-type ATPase family, encoding key factors in regulating silk fibrillogenesis 41 , were significantly upregulated in both the Duct and ASG (Fig. 5g).…”