Characterization of Arabidopsis Eukaryotic Translation Initiation Factor 2α (eIF2α) Mutants

Plants are stationary organisms that are charged with overcoming a multitude of biotic and abiotic stresses. The eukaryotic translation initiation factor 2 (eIF2) is responsible for charging the P-site of the forming 80S ribosome with the initiator methionyl-tRNA. Thus, eIF2 is a protein of utmost consequence in the growth and development of organisms. The eIF2 protein is also a mediator of global translational regulation in the eukaryotic integrated stress response (ISR), where the α-subunit is phosphorylated by protein kinases, such as the kinase GCN2. Here, five eIF2α allele mutants in Arabidopsis were found to be deleterious to plant growth, development, and reproduction. Additionally, eIF2α RNA and protein were expressed at variable levels in eIF2α mutant seedlings and maturing rosette-stage plants. Plants overexpressing eIF2α wild-type and phospho-variant alleles had altered root lengths and displayed variable growth defects at the rosette and reproductive stages. Finally, recombinant forms of eIF2α, an alleged partner protein ABCF1, and the GCN2-kinase domain were expressed and purified from an E. coli cell line. These data demonstrate that the eIF2α gene plays a vital role in the growth and development of seedlings and mature Arabidopsis plants and overexpression of eIF2α disrupts the native development of plant structures.