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Novel RNA-Binding Proteins Isolation by the RaPID Methodology
11:19

Novel RNA-Binding Proteins Isolation by the RaPID Methodology

Published on: September 30, 2016

Tab2 is a novel conserved RNA binding protein required for translation of the chloroplast psaB mRNA

David Dauvillée1, Otello Stampacchia, Jacqueline Girard-Bascou

  • 1Department of Molecular Biology, University of Geneva, 30 Quai Ernest Ansermet 1211 Geneva 4, Switzerland.

The EMBO Journal
|November 25, 2003
PubMed

Insights

A nuclear gene, TAB2, is crucial for translating psaB mRNA, essential for photosystem I activity in Chlamydomonas reinhardtii. This protein directly binds the psaB mRNA, facilitating chloroplast development and function.

Area of Science:

  • Photosynthesis research
  • Chloroplast biology
  • Molecular genetics

Background:

  • Photosystem I (PSI) is vital for photosynthesis, utilizing the psaB mRNA-encoded polypeptide.
  • Mutant F14 in Chlamydomonas reinhardtii shows impaired PSI activity due to translation issues with psaB mRNA.
  • The nuclear gene TAB2 has been identified as a key factor in this process.

Purpose of the Study:

  • To identify and characterize the nuclear gene TAB2 responsible for psaB mRNA translation.
  • To elucidate the mechanism by which Tab2 protein regulates PsaB synthesis and PSI assembly.
  • To understand the role of Tab2 in oxygenic photosynthesis.

Main Methods:

  • Genetic analysis of Chlamydomonas reinhardtii mutant F14.
  • Genomic complementation to isolate the TAB2 gene.
  • Protein sequence analysis and directed mutagenesis.
  • Chloroplast protein localization studies and gel mobility shift assays.

Main Results:

  • The TAB2 gene was isolated, encoding a 358-residue protein with conserved orthologues in photosynthetic organisms.
  • A conserved C-terminal tripeptide in Tab2 is essential for psaB translation.
  • Tab2 protein localizes to the chloroplast stroma and directly binds the 5'UTR of psaB mRNA within a protein complex.
  • The F14 mutant exhibits deficiency in psaB mRNA translation and PSI activity.

Conclusions:

  • Tab2 is a nuclear-encoded protein essential for the translation of psaB mRNA.
  • Tab2 directly interacts with the psaB mRNA 5'UTR, likely initiating PsaB synthesis.
  • This interaction is critical for efficient photosystem I assembly and function in Chlamydomonas reinhardtii.

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