A nuclear redox sensor modulates gene activation and var switching in Plasmodium falciparum

Adina Heinberg, Inbar Amit-Avraham, Vera Mitesser, Karina Simantov, Manish Goyal, Yuval Nevo, Sofia Kandelis-Shalev, Emilie Thompson, Ron Dzikowski

Research output: Contribution to journalArticlepeer-review

Abstract

The virulence of Plasmodium falciparum, which causes the deadliest form of human malaria, is attributed to its ability to evade the human immune response. These parasites “choose” to express a single variant from a repertoire of surface antigens called PfEMP1, which are placed on the surface of the infected red cell. Immune evasion is achieved by switches in expression between var genes, each encoding a different Pf EMP1 variant. While the mechanisms that regulate mutually exclusive expression of var genes are still elusive, antisense long-noncoding RNAs (lncRNAs) transcribed from the intron of the active var gene were implicated in the “choice” of the single active var gene. Here, we show that this lncRNA colocalizes with the site of var mRNA transcription and is anchored to the var locus via DNA:RNA interactions. We define the var lncRNA interactome and identify a redox sensor, P. falciparum thioredoxin peroxidase I (Pf TPx-1), as one of the proteins associated with the var antisense lncRNA. We show that Pf TPx-1 localizes to a nuclear subcompartment associated with active transcription on the nuclear periphery, in ring-stage parasite, when var transcription occurs. In addition, Pf TPx-1 colocalizes with S-adenosylmethionine synthetase (Pf SAMS) in the nucleus, and its overexpression leads to activation of var2csa, similar to overexpression of Pf SAMS. Furthermore, we show that Pf TPx-1 knockdown alters the var switch rate as well as activation of additional gene subsets. Taken together, our data indicate that nuclear Pf TPx-1 plays a role in gene activation possibly by providing a redox-controlled nuclear microenvironment ideal for active transcription.

Original languageAmerican English
Article numbere2201247119
JournalProceedings of the National Academy of Sciences of the United States of America
Volume119
Issue number33
DOIs
StatePublished - 16 Aug 2022

Keywords

  • Plasmodium falciparum
  • lncRNA
  • malaria
  • thioredoxin peroxidase
  • var genes

All Science Journal Classification (ASJC) codes

  • General

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