Molecular blueprint behind spider silk : a multi-omics study of the major and minor ampullate glands

Abstract

Spider silk fibers exhibit exceptional mechanical properties, inspiring efforts to develop artificial analogues. Specifically, major ampullate silk is renowned for its high tensile strength and toughness, while minor ampullate silk exhibits higher extensibility and water resistance. However, replicating these properties remains challenging due to limited knowledge of silk biosynthesis. This thesis investigates the molecular basis of silk production in the bridge spider, Larinioides sclopetarius, focusing on major and minor ampullate glands.  

Histological analysis revealed cellular compartmentalization and layered secretion in most silk glands, suggesting a complex and multi-layered structure for the corresponding fibers. The presence of active carbonic anhydrase in most glands suggests potential pH gradients. We identified 18 predominant proteins in major ampullate silk, which are produced and secreted from five cell types organized into three epithelial zones (A, B, & C) in the gland. These secretions do not mix but form distinct layers in the lumen and persist in the silk fiber. Based on these findings, we proposed a three-layered model for the silk with major ampullate spidroin 1 (MaSp1), MaSp2, MaSp4 in the inner layer; MaSp3 and ampullate-like spidroins in the middle; and a heterogeneous class of non-spidroin proteins termed spider-silk constituting elements (SpiCE) in the outer layer. Similar cellular organization and layered secretion were observed in minor ampullate glands, with three cell types confined to three epithelial zones (A, B, & C). A comparative analysis revealed shared and distinct cellular compositions and gene expression profiles between the two ampullate glands. We further suggest that the minor ampullate silk has a multi-layered structure, analogous to major ampullate silk, but with distinct protein compositions. 

This research provides novel insights into the cellular and molecular mechanisms underlying major and minor ampullate silk production. Our findings provide vital information for future efforts in the development of bioinspired materials with enhanced properties.

Keywords

silk biology; silk fiber; silk bioprocessing; single cell RNA sequencing; spatial transcriptomics

Published in

Acta Universitatis Agriculturae Sueciae
2024, number: 2024:56ISBN: 978-91-8046-052-1, eISBN: 978-91-8046-053-8Publisher: Swedish University of Agricultural Sciences

SLU Authors

• Sonavane, Sumalata

  • Department of Animal Biosciences, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Cell Biology
Biochemistry and Molecular Biology


Publication identifier

DOI: https://doi.org/10.54612/a.1evrucb870

Permanent link to this page (URI)

https://res.slu.se/id/publ/128775