Shuttling of (deoxy‐) purine nucleotides between compartments of the diatom Phaeodactylum tricornutum. Issue 1 (9th August 2016)

• Record Type: Journal Article
• Authors: Chu, Lili; Gruber, Ansgar; Ast, Michelle; Schmitz‐Esser, Stephan; Altensell, Jacqueline; Neuhaus, Horst Ekkehard; Kroth, Peter G.; Haferkamp, Ilka
• Is Part Of: New phytologist. Volume 213:Issue 1(2017)
• Page Start: 193
• Page End: 205
• Publication Date: 2016-08-09
• Subjects: complex plastid -- diatom -- endoplasmic reticulum (ER) -- energy -- nucleotide synthesis -- nucleotide transport; Botany -- Periodicals; 580
• DOI: 10.1111/nph.14126
• Languages: English
• ISSNs: 0028-646X

Abstract

Summary: Diatom plastids show several peculiarities when compared with primary plastids of higher plants or algae. They are surrounded by four membranes and depend on nucleotide uptake because, unlike in plants, nucleotide de novo synthesis exclusively occurs in the cytosol. Previous analyses suggest that two specifically adapted nucleotide transporters (NTTs) facilitate the required passage of nucleotides across the innermost plastid membrane. However, nucleotide transport across the additional plastid membranes remains to be clarified. Phylogenetic studies, transport assays with the recombinant protein as well as GFP‐based targeting analyses allowed detailed characterization of a novel isoform ( Pt NTT5) of the six NTTs of Phaeodactylum tricornutum . Pt NTT5 exhibits low amino acid similarities and is only distantly related to all previously characterized NTTs. However, in a heterologous expression system, it acts as a nucleotide antiporter and prefers various (deoxy‐) purine nucleotides as substrates. Interestingly, Pt NTT5 is probably located in the endoplasmic reticulum, which in diatoms also represents the outermost plastid membrane. Pt NTT5, with its unusual transport properties, phylogeny and localization, can be taken as further evidence for the establishment of a sophisticated and specifically adapted nucleotide transport system in diatom plastids.