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High intracellular stability of the spidroin N‐terminal domain in spite of abundant amyloidogenic segments revealed by in‐cell hydrogen/deuterium exchange mass spectrometry
Author(s) -
Kaldmäe Margit,
Leppert Axel,
Chen Gefei,
Sarr Medoune,
Sahin Cagla,
Nordling Kerstin,
Kronqvist Nina,
GonzalvoUlla Marta,
Fritz Nicolas,
Abelein Axel,
Laίn Sonia,
Biverstål Henrik,
Jörnvall Hans,
Lane David P.,
Rising Anna,
Johansson Jan,
Landreh Michael
Publication year - 2020
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.15169
Subject(s) - hydrogen–deuterium exchange , biophysics , chemistry , cytosol , intracellular , mass spectrometry , spider silk , amyloid (mycology) , silk , biochemistry , biology , chromatography , materials science , inorganic chemistry , composite material , enzyme
Proteins require an optimal balance of conformational flexibility and stability in their native environment to ensure their biological functions. A striking example is spidroins, spider silk proteins, which are stored at extremely high concentrations in soluble form, yet undergo amyloid‐like aggregation during spinning. Here, we elucidate the stability of the highly soluble N‐terminal domain (NT) of major ampullate spidroin 1 in the Escherichia coli cytosol as well as in inclusion bodies containing fibrillar aggregates. Surprisingly, we find that NT, despite being largely composed of amyloidogenic sequences, showed no signs of concentration‐dependent aggregation. Using a novel intracellular hydrogen/deuterium exchange mass spectrometry (HDX‐MS) approach, we reveal that NT adopts a tight fold in the E. coli cytosol and in this manner conceals its aggregation‐prone regions by maintaining a tight fold under crowded conditions. Fusion of NT to the unstructured amyloid‐forming Aβ 40 peptide, on the other hand, results in the formation of fibrillar aggregates. However, HDX‐MS indicates that the NT domain is only partially incorporated into these aggregates in vivo . We conclude that NT is able to control its aggregation to remain functional under the extreme conditions in the spider silk gland.