Structural symmetry: The three-dimensional structure of Haemophilus influenzae diaminopimelate epimerase

Maurizio Cirilli, Renjian Zheng, Giovanna Scapin, John S. Blanchard

Research output: Contribution to journalArticle

66 Scopus citations

Abstract

The Haemophilus influenzae diaminopimelate epimerase was cloned, expressed, purified, and crystallized in the C2221 space group (a = 102.1 Å, b = 115.4 Å, c = 66.3 Å, α = β = γ = 90≡). The three-dimensional structure was solved to 2.7 Å using a single Pt derivative and the Se-Met- substituted enzyme to a conventional R factor of 19.0% (R(free) = 24.2%). The 274 amino acid enzyme consists of two structurally homologous domains, each containing eight β-strands and two α-helices. Diaminopimelate epimerase is a representative of the PLP-independent amino acid racemases, for which no structure has yet been determined and substantial evidence exists supporting the role of two cysteine residues as the catalytic acid and base. Cys73 of the-amino terminal domain is found in disulfide linkage, at the domain interface, with Cys217 of the carboxy terminal domain, and we suggest that these two cysteine residues in the reduced, active enzyme function as the acid and base in the mechanism.

Original languageEnglish (US)
Pages (from-to)16452-16458
Number of pages7
JournalBiochemistry
Volume37
Issue number47
DOIs
StatePublished - Nov 24 1998

ASJC Scopus subject areas

  • Biochemistry

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