Translation Initiation Factor eIF4E Positively Modulates Conidiogenesis, Appressorium Formation, Host Invasion and Stress Homeostasis in the Filamentous Fungi Magnaporthe oryzae.

Wajjiha Batool,Qiuli An,Justice Norvienyeku,Qinghe Chen,Zonghua Wang,Lili Lin,Shu Pan,Xiongjie He,Ammarah Shabbir,Shuzun Chen,Xiaomin Chen

doi:10.3389/fpls.2021.646343

Abstract

Translation initiation factor eIF4E generally mediates the recognition of the 5’cap structure of mRNA during the recruitment of the ribosomes to capped mRNA. Although the eIF4E has been shown to regulate stress response in Schizosaccharomyces pombe positively, there is no direct experimental evidence for the contributions of eIF4E to both physiological and pathogenic development of filamentous fungi. We generated Magnaporthe oryzae eIF4E (MoeIF4E3) gene deletion strains using homologous recombination strategies. Phenotypic and biochemical analyses of MoeIF4E3 defective strains showed that the deletion of MoeIF4E3 triggered a significant reduction in growth and conidiogenesis. We also showed that disruption of MoeIF4E3 partially impaired conidia germination, appressorium integrity and attenuated the pathogenicity of ΔMoeif4e3 strains. In summary, this study provides experimental insights into the contributions of the eIF4E3 to the development of filamentous fungi. Additionally, these observations underscored the need for a comprehensive evaluation of the translational regulatory machinery in phytopathogenic fungi during pathogen-host interaction progression.

Highlights

Transcriptional and translational regulation of gene expression plays a central role in cell differentiation, physiological development and regulates cellular processes that enable living organisms to readily adapt to harsh or changing environmental conditions (Thach, 1992)
Blast search analysis identified a putative eukaryotic translation initiation factor 4E (eIF4E) protein (MoeIF4E3) encoded by a gene with the open reading frame MGG_08170, whereas results obtained from the Kyoto Encyclopedia for Genes and Genomes (KEGG) database assisted blast analysis identified two more M. oryzae eIF4E proteins MoeIF4E and MoeIF4E1 along with MoeIF4E3
Protein sequence similarity index recorded for MoeIF4E and MoeIF4E1 comparative to eIF4E3 sequences identified from B. cinerea, F. graminearum, and N. crassa has lower than 40% sequence similarity while MoeIF4E3 recorded sequence similarity index of ∼60%, indicating that M. oryzae most likely exist as a single copy, MoeIF4E3 (MGG_08170)

Summary

Introduction

Transcriptional and translational regulation of gene expression plays a central role in cell differentiation, physiological development and regulates cellular processes that enable living organisms to readily adapt to harsh or changing environmental conditions (Thach, 1992). Translation initiation events play a fundamental but crucial role in gene expression by regulating eIF4E3 Modulates Stress Homeostasis and Pathogenesis the assemblage of the cellular machinery required to transform mRNAs to protein (translation). The eIF4F complex comprises three subunits (eIF4A, eIF4E, and eIF4G) that mediate the translational regulation of mRNAs in a capdependent manner and selectively regulate the translation of a large proportion of mRNAs by modulating the binding of the 43S pre-initiation complex to mRNAs (Aitken and Lorsch, 2012). The eIF4E of the eIF4F complex activates the translational initiation process by encasing the 5 cap (methylated Guanine) of eukaryotic mRNA. To regulate the activity of eIF4E, eukaryotic translation initiation factor 4E-binding protein (4E-BP) and eIF4G are considered as key proteins in cap-dependent translation (Gallagher et al, 2019)

Methods

Results

Conclusion