Biophysical and bioinformatic analyses implicate the treponema pallidum tp34 lipoprotein (tp0971) in transition metal homeostasis

Chad A Brautigam, Ranjit K. Deka, Zhiming Ouyang, Mischa Machius, Gregory Knutsen, Diana R Tomchick, Michael V Norgard

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Metal ion homeostasis is a critical function of many integral and peripheral membrane proteins. The genome of the etiologic agent of syphilis, Treponema pallidum, is compact and devoid of many metabolic enzyme genes. Nevertheless, it harbors genes coding for homologs of several enzymes that typically require either iron or zinc. The product of the tp0971 gene of T. pallidum, designated Tp34, is a periplasmic lipoprotein that is thought to be tethered to the inner membrane of this organism. Previous work on a water-soluble (nonacylated) recombinant version of Tp34 established that this protein binds to Zn2+, which, like other transition metal ions, stabilizes the dimeric form of the protein. In this study, we employed analytical ultracentrifugation to establish that four transition metal ions (Ni2+, Co2+, Cu2+, and Zn2+) readily induce the dimerization of Tp34; Cu2+ (50% effective concentration [EC50]=1.7 μM) and Zn2+ (EC50=6.2 μM) were the most efficacious of these ions. Mutations of the crystallographically identified metal-binding residues hindered the ability of Tp34 to dimerize. X-ray crystallography performed on crystals of Tp34 that had been incubated with metal ions indicated that the binding site could accommodate the metals examined. The findings presented herein, coupled with bioinformatic analyses of related proteins, point to Tp34's likely role in metal ion homeostasis in T. pallidum.

Original languageEnglish (US)
Pages (from-to)6771-6781
Number of pages11
JournalJournal of Bacteriology
Volume194
Issue number24
DOIs
StatePublished - Oct 2012

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Treponema pallidum
Computational Biology
Lipoproteins
Homeostasis
Metals
Ions
Genes
Proteins
Ultracentrifugation
X Ray Crystallography
Dimerization
Enzymes
Syphilis
Zinc
Membrane Proteins
Iron
Binding Sites
Genome
Mutation
Membranes

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

Cite this

Biophysical and bioinformatic analyses implicate the treponema pallidum tp34 lipoprotein (tp0971) in transition metal homeostasis. / Brautigam, Chad A; Deka, Ranjit K.; Ouyang, Zhiming; Machius, Mischa; Knutsen, Gregory; Tomchick, Diana R; Norgard, Michael V.

In: Journal of Bacteriology, Vol. 194, No. 24, 10.2012, p. 6771-6781.

Research output: Contribution to journalArticle

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