Horizontal gene transfer of "prototype" Nramp in bacteria

J Mol Evol. 2003 Oct;57(4):363-76. doi: 10.1007/s00239-003-2472-z.

Abstract

Eukaryotic Nramp genes encode divalent metal ion permeases important for nutrition and resistance to microbial infection. Bacterial homologs encode proton-dependent transporters of manganese (MntH), and other divalent metal ions. Bacterial MntH were classified in three homology groups (A, B, C) and MntH C further subdivided in Calpha, Cbeta, Cgamma. The proteins from C. tepidum (MntH B) and E. faecalis (MntH Cbeta1, 2), divergent in sequence and hydropathy profile, conferred increased metal sensitivity when expressed in E. coli, suggesting conservation of divalent metal transport function in MntH B and C. Several genomic evidence suggest horizontal gene transfer (HGT) of mntH C genes: (i) The enterobacteria Wigglesworthia mntH Cbeta gene is linked to an Asn t-RNA, and its sequence most conserved with Gram positive bacteria homologs; (ii) all the Cbeta genes identified in oral streptococcaceae are associated with different potentially mobile DNA elements; (iii) Lactococcus lactis and Burkholderia mallei genomes contain an mntH gene prematurely terminated and a novel full-length mntH C gene; (iv) remarkable sequence relatedness between the unicellular alga C. reinhardtii "prototype" Nramp and some MntH Calpha (e.g., Nostoc spp., Listeria spp.) suggests HGT between Eukarya and Bacteria. Other "prototype" Nramp genes (intronless, encoding proteins strongly conserved with MntH A and B proteins) identified in invertebrates represent a possible source for transfer of Nramp genes toward opportunistic bacteria. This study demonstrates complex evolution of MntH in Bacteria. It is proposed that "prototype" Nramp are ancestors of bacterial MntH C proteins, which could facilitate bacterial infection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacteria / genetics*
  • Bacterial Proteins*
  • Biological Transport
  • Carrier Proteins / classification
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Cation Transport Proteins / genetics*
  • DNA Transposable Elements / genetics
  • Escherichia coli / genetics
  • Escherichia coli Proteins*
  • Eukaryotic Cells / metabolism
  • Gene Transfer, Horizontal / genetics*
  • Genes, Bacterial / genetics*
  • Genetic Linkage / genetics
  • Metals / metabolism
  • Open Reading Frames / genetics
  • Phylogeny
  • Streptococcaceae / genetics
  • Wigglesworthia / genetics

Substances

  • Bacterial Proteins
  • Carrier Proteins
  • Cation Transport Proteins
  • DNA Transposable Elements
  • Escherichia coli Proteins
  • Metals
  • MntH protein, E coli
  • MntH protein, bacteria
  • natural resistance-associated macrophage protein 1