Biological functions of Arabidopsis thaliana MBP-1-like protein encoded by ENO2 in the response to drought and salt stresses.

Arabidopsis thaliana ENO2 (AtENO2) plays an important role in plant growth and development. It encodes two proteins, a full-length AtENO2 and a truncated version, AtMBP-1, alternatively translated from the second start codon of the mRNA. The AtENO2 mutant (eno2- ) exhibited reduced leaf size, shortened siliques, a dwarf phenotype and higher sensitivity to abiotic stress. The objectives of this study were to analyze the regulatory network of the ENO2 gene in plant growth development and understand the function of AtENO2/AtMBP-1 to abiotic stresses. An eno2- /35S:AtENO2-GFP line and an eno2- /35S:AtMBP-1-GFP line of Arabidopsis were obtained. Results of sequencing by 454 GS FLX identified 578 upregulated and 720 downregulated differential expressed genes (DEGs) in a pairwise comparison (WT-VS-eno2- ). All the high-quality reads were annotated using the Gene Ontology (GO) terms. The DEGs with KEGG pathway annotations occurred in 110 pathways. The metabolic pathways and biosynthesis of secondary metabolites contained more DEGs. Moreover, the eno2- /35S:AtENO2-GFP line returned to the wild-type (WT) phenotype and was tolerant to drought and salt stresses. However, the eno2- /35S:AtMBP-1-GFP line was not able to recover the WT phenotype but it has a higher tolerance to drought and salt stresses. Results from this study demonstrate that AtENO2 is critical for the growth and development, and the AtMBP-1 coded by AtENO2 is important in tolerance of Arabidopsis to abiotic stresses.

[Research progress in the mechanism of translation initiation of eukaryotic mRNAs].

The translation of mRNA is a complicated multi-step process, including initiation, elongation and termination. Among them, the regulation of the initial stage plays the key role. There are many ways to initiate mRNA translation, and the most classical way is the m 7G cap-dependent scanning mechanism that was also the first mechanism identified. When cells encounter adversity and the classical mechanism is inhibited, other types of translation initiation mechanisms will be activated. In this review, we summarize the translation initiation mechanisms of eukaryotic mRNAs, especially some alternative mechanisms. It will provide a reference for further understanding of the expression and regulation of eukaryotic genes at the translation levels.