A novel transporter involved in cobalt uptake

Proc Natl Acad Sci U S A. 1997 Jan 7;94(1):36-41. doi: 10.1073/pnas.94.1.36.

Abstract

Cobalt is an essential component of a low molecular-mass nitrile hydratase (L-NHase) from Rhodococcus rhodochrous J1. We have found a new gene, nhlF, in the DNA region sandwiched between nhlBA encoding L-NHase and amdA encoding amidase, which are involved in the degradation of nitriles. The product of nhlF, NhlF, shows a significant sequence similarity with those of hoxN from Alcaligenes eutrophus, hupN from Bradyrhizobium japonicum, nixA from Helicobacter pylori, and ureH from Bacillus sp., which are considered to be involved in nickel uptake into these cells. Sequence and hydropathy plot analyses have shown that NhlF encodes a 352-amino acid (aa) protein with eight hydrophobic putative membrane-spanning domains. nhlF expression in R. rhodochrous ATCC 12674 and Escherichia coli JM109 confers uptake of 57Co in their cells, but not of 63Ni. The expression of both nhlF and nhlBA in R. rhodochrous ATCC 12674 exhibited higher NHase activity than nhlBA expression. These findings together with the inhibitory effect by uncouplers (CCCP and SF6847) for the cobalt uptake suggest that NhlF mediates the cobalt transport into the cell energy-dependently finally to provide L-NHase.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism
  • Biological Transport / drug effects
  • Carrier Proteins / genetics*
  • Carrier Proteins / metabolism
  • Cation Transport Proteins*
  • Cations, Divalent / pharmacology
  • Cobalt / metabolism*
  • Fungal Proteins*
  • Genes, Bacterial*
  • Hydro-Lyases / biosynthesis
  • Hydro-Lyases / genetics
  • Membrane Proteins / genetics*
  • Membrane Proteins / metabolism
  • Molecular Sequence Data
  • Rhodococcus / genetics*
  • Rhodococcus / metabolism
  • Sequence Analysis, DNA
  • Sequence Homology, Amino Acid
  • Trans-Activators / genetics
  • Transformation, Genetic
  • Uncoupling Agents / pharmacology

Substances

  • AmdA protein, Aspergillus nidulans
  • Bacterial Proteins
  • Carrier Proteins
  • Cation Transport Proteins
  • Cations, Divalent
  • Fungal Proteins
  • Membrane Proteins
  • NhlF protein, Rhodococcus rhodochrous
  • Trans-Activators
  • Uncoupling Agents
  • Cobalt
  • Hydro-Lyases
  • nitrile hydratase

Associated data

  • GENBANK/D83695