The neuroendocrine protein 7B2 is intrinsically disordered.

Published

Journal Article

The small neuroendocrine protein 7B2 has been shown to be required for the productive maturation of proprotein convertase 2 (proPC2) to an active enzyme form; this action is accomplished via its ability to block aggregation of proPC2 into nonactivatable forms. Recent data show that 7B2 can also act as a postfolding chaperone to block the aggregation of a number of other proteins, for example, α-synuclein. To gain insight into the mechanism of action of 7B2 in blocking protein aggregation, we performed structural studies of this protein using gel filtration chromatography, intrinsic tryptophan fluorescence, 1-anilino-8-naphthalenesulfonate (ANS) binding, circular dichroism (CD), and nuclear magnetic resonance (NMR) spectroscopy. Gel filtration studies indicated that 7B2 exists as an extended monomer, eluting at a molecular mass higher than that expected for a globular protein of similar size. However, chemical cross-linking showed that 7B2 exhibits concentration-dependent oligomerization. CD experiments showed that both full-length 27 kDa 7B2 and the C-terminally truncated 21 kDa form lack appreciable secondary structure, although the longer protein exhibited more structural content than the latter, as demonstrated by intrinsic and ANS fluorescence studies. NMR spectra confirmed the lack of structure in native 7B2, but a disorder-to-order transition was observed upon incubation with one of its client proteins, α-synuclein. We conclude that 7B2 is a natively disordered protein whose function as an antiaggregant chaperone is likely facilitated by its lack of appreciable secondary structure and tendency to form oligomers.

Full Text

Cited Authors

  • Dasgupta, I; Sanglas, L; Enghild, JJ; Lindberg, I

Published Date

  • September 14, 2012

Published In

Volume / Issue

  • 51 / 38

Start / End Page

  • 7456 - 7464

PubMed ID

  • 22947085

Pubmed Central ID

  • 22947085

Electronic International Standard Serial Number (EISSN)

  • 1520-4995

International Standard Serial Number (ISSN)

  • 0006-2960

Digital Object Identifier (DOI)

  • 10.1021/bi300871k

Language

  • eng