Format

Send to

Choose Destination
Plant Physiol. 2019 Sep;181(1):85-96. doi: 10.1104/pp.19.00557. Epub 2019 Jul 15.

eIFiso4G Augments the Synthesis of Specific Plant Proteins Involved in Normal Chloroplast Function.

Author information

1
Department of Molecular Biosciences and The Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712.
2
Arkansas Biosciences Institute, Arkansas State University, State University, Arkansas 72467.
3
Division of Biochemistry and Molecular Biology, Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803.
4
School of Biological Sciences, Washington State University, Pullman, Washington 99164-4236.
5
Department of Molecular Biosciences and The Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712 kbrowning@cm.utexas.edu.

Abstract

The plant-specific translation initiation complex eIFiso4F is encoded by three genes in Arabidopsis (Arabidopsis thaliana)-genes encoding the cap binding protein eIFiso4E (eifiso4e) and two isoforms of the large subunit scaffolding protein eIFiso4G (i4g1 and i4g2). To quantitate phenotypic changes, a phenomics platform was used to grow wild-type and mutant plants (i4g1, i4g2, i4e, i4g1 x i4g2, and i4g1 x i4g2 x i4e [i4f]) under various light conditions. Mutants lacking both eIFiso4G isoforms showed the most obvious phenotypic differences from the wild type. Two-dimensional differential gel electrophoresis and mass spectrometry were used to identify changes in protein levels in plants lacking eIFiso4G. Four of the proteins identified as measurably decreased and validated by immunoblot analysis were two light harvesting complex binding proteins 1 and 3, Rubisco activase, and carbonic anhydrase. The observed decreased levels for these proteins were not the direct result of decreased transcription or protein instability. Chlorophyll fluorescence induction experiments indicated altered quinone reduction kinetics for the double and triple mutant plants with significant differences observed for absorbance, trapping, and electron transport. Transmission electron microscopy analysis of the chloroplasts in mutant plants showed impaired grana stacking and increased accumulation of starch granules consistent with some chloroplast proteins being decreased. Rescue of the i4g1 x i4g2 plant growth phenotype and increased expression of the validated proteins to wild-type levels was obtained by overexpression of eIFiso4G1. These data suggest a direct and specialized role for eIFiso4G in the synthesis of a subset of plant proteins.

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center