Methanobactin transport machinery

Laura M.K. Dassama, Grace E. Kenney, Soo Y. Ro, Eliza L. Zielazinski, Amy C. Rosenzweig*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

Methanotrophic bacteria use methane, a potent greenhouse gas, as their primary source of carbon and energy. The first step in methane metabolism is its oxidation to methanol. In almost all methanotrophs, this chemically challenging reaction is catalyzed by particulate methane monooxygenase (pMMO), a copper-dependent integral membrane enzyme. Methanotrophs acquire copper (Cu) for pMMO by secreting a small ribosomally produced, posttranslationally modified natural product called methanobactin (Mbn). Mbn chelates Cu with high affinity, and the Cu-loaded form (CuMbn) is reinternalized into the cell via an active transport process. Bioinformatic and gene regulation studies suggest that two proteins might play a role in CuMbn handling: the TonB-dependent transporter MbnT and the periplasmic binding protein MbnE. Disruption of the gene that encodes MbnT abolishes CuMbn uptake, as reported previously, and expression of MbnT in Escherichia coli confers the ability to take up CuMbn. Biophysical studies of MbnT and MbnE reveal specific interactions with CuMbn, and a crystal structure of apo MbnE is consistent with MbnE's proposed role as a periplasmic CuMbn transporter. Notably, MbnT and MbnE exhibit different levels of discrimination between cognate and noncognate CuMbns. These findings provide evidence for CuMbn-protein interactions and begin to elucidate the molecular mechanisms of its recognition and transport.

Original languageEnglish (US)
Pages (from-to)13027-13032
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume113
Issue number46
DOIs
StatePublished - Nov 15 2016

Keywords

  • Chalkophore
  • Copper transport
  • Metal homeostasis
  • Methane monooxygenase
  • Methanobactin

ASJC Scopus subject areas

  • General

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