Chemical cross-linking of the urease complex from Helicobacter pylori and analysis by Fourier transform ion cyclotron resonance mass spectrometry and molecular modeling

Elisabet Carlsohn, Jonas Ångström, Mark R. Emmett, Alan G. Marshall, Carol L. Nilsson

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

Chemical cross-linking of proteins is a well-established method for structural mapping of small protein complexes. When combined with mass spectrometry, cross-linking can reveal protein topology and identify contact sites between the peptide surfaces. When applied to surface-exposed proteins from pathogenic organisms, the method can reveal structural details that are useful in vaccine design. In order to investigate the possibilities of applying cross-linking on larger protein complexes, we selected the urease enzyme from Helicobacter pylori as a model. This membrane-associated protein complex consists of two subunits: α (26.5 kDa) and β (61.7 kDa). Three (αβ) heterodimers form a trimeric (αβ)3 assembly which further associates into a unique dodecameric 1.1 MDa complex composed of four (αβ)3 units. Cross-linked peptides from trypsin-digested urease complex were analyzed by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and molecular modeling. Two potential cross-linked peptides (present in the cross-linked sample but undetectable in α, β, and native complex) were assigned. Molecular modeling of urease αβ complex and trimeric urease units (αβ)3 revealed a linkage site between the α-subunit and the β-subunit, and an internal cross-linkage in the β-subunit.

Original languageEnglish (US)
Pages (from-to)137-144
Number of pages8
JournalInternational Journal of Mass Spectrometry
Volume234
Issue number1-3
DOIs
StatePublished - May 1 2004

Keywords

  • Cross-linking
  • FT-ICR MS
  • FTMS
  • Molecular modeling
  • Urease

ASJC Scopus subject areas

  • Instrumentation
  • Condensed Matter Physics
  • Spectroscopy
  • Physical and Theoretical Chemistry

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