Genetic redundancy in iron and manganese transport in the metabolically versatile bacterium rhodopseudomonas palustris TIE-1

Rajesh Singh, Tahina Onina Ranaivoarisoa, Dinesh Gupta, Wei Bai, Arpita Bose

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5 Scopus citations


The purple nonsulfur bacterium Rhodopseudomonas palustris TIE-1 can produce useful biochemicals such as bioplastics and biobutanol. Production of such biochemicals requires intracellular electron availability, which is governed by the availability and the transport of essential metals such as iron (Fe). Because of the distinct chemical properties of ferrous [Fe(II)] and ferric iron [Fe(III)], different systems are required for their transport and storage in bacteria. Although Fe(III) transport systems are well characterized, we know much less about Fe(II) transport systems except for the FeoAB system. Iron transporters can also import manganese (Mn). We studied Fe and Mn transport by five putative Fe transporters in TIE-1 under metalreplete, metal-depleted, oxic, and anoxic conditions. We observed that by overexpressing feoAB, efeU, and nramp1AB, the intracellular concentrations of Fe and Mn can be enhanced in TIE-1 under oxic and anoxic conditions, respectively. The deletion of a single gene/operon does not attenuate Fe or Mn uptake in TIE-1 regardless of the growth conditions used. This indicates that genetically dissimilar yet functionally redundant Fe transporters in TIE-1 can complement each other. Relative gene expression analysis shows that feoAB and efeU are expressed during Fe and Mn depletion under both oxic and anoxic conditions. The promoters of these transporter genes contain a combination of Fur and Fnr boxes, suggesting that their expression is regulated by both Fe and oxygen availability. The findings from this study will help us modulate intracellular Fe and Mn concentrations, ultimately improving TIE-1's ability to produce desirable biomolecules.

Original languageEnglish
Pages (from-to)1-21
Number of pages21
JournalApplied and Environmental Microbiology
Issue number16
StatePublished - Aug 1 2020


  • Biofuels and bioplastics
  • Bioproduction
  • EfeU
  • FeoAB
  • Iron transporters
  • Microbial chassis
  • Rhodopseudomonas palustris TIE-1


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