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Research article - Peer-reviewed, 2014

Sequential pH-driven dimerization and stabilization of the N-terminal domain enables rapid spider silk formation

Kronqvist, Nina; Otikovs, Martins; Chmyrov, Volodymyr; Chen, Gefei; Andersson, Marlene; Nordling, Kerstin; Landreh, Michael; Sarr, Medoune; Jörnvall, Hans; Wennmalm, Stefan; Widengren, Jerker; Meng, Qing; Rising, Anna; Otzen, Daniel; Knight, Stefan D.; Johansson, Jan

Abstract

The mechanisms controlling the conversion of spider silk proteins into insoluble fibres, which happens in a fraction of a second and in a defined region of the silk glands, are still unresolved. The N-terminal domain changes conformation and forms a homodimer when pH is lowered from 7 to 6; however, the molecular details still remain to be determined. Here we investigate site-directed mutants of the N-terminal domain from Euprosthenops australis major ampullate spidroin 1 and find that the charged residues D40, R60 and K65 mediate intersubunit electrostatic interactions. Protonation of E79 and E119 is required for structural conversions of the subunits into a dimer conformation, and subsequent protonation of E84 around pH 5.7 leads to the formation of a fully stable dimer. These residues are highly conserved, indicating that the now proposed three-step mechanism prevents premature aggregation of spidroins and enables fast formation of spider silk fibres in general.

Published in

Nature Communications
2014, volume: 5
Publisher: NATURE PUBLISHING GROUP

Authors' information

Kronqvist, Nina
Karolinska Institute
Otikovs, Martins
Latvian Institute of Organic Synthesis
Chmyrov, Volodymyr
Royal Institute of Technology (KTH)
Chen, Gefei
Andersson, Marlene
Swedish University of Agricultural Sciences, Department of Anatomy, Physiology and Biochemistry (AFB)
Nordling, Kerstin
Landreh, Michael
Sarr, Medoune
Karolinska Institute
Jörnvall, Hans
Karolinska Institute
Wennmalm, Stefan
Royal Institute of Technology (KTH)
Widengren, Jerker
Royal Institute of Technology (KTH)
Meng, Qing
Donghua University
Swedish University of Agricultural Sciences, Department of Anatomy, Physiology and Biochemistry (AFB)
Otzen, Daniel
Aarhus University
Knight, Stefan D.
Uppsala University
Johansson, Jan
Swedish University of Agricultural Sciences, Department of Anatomy, Physiology and Biochemistry (AFB)

UKÄ Subject classification

Biochemistry and Molecular Biology
Structural Biology

Publication Identifiers

DOI: https://doi.org/10.1038/ncomms4254

URI (permanent link to this page)

https://res.slu.se/id/publ/53204