In the yeast Saccharomyccs cerevwise, qiutations in either of two unlinked genes, RAM)-1or RAM2, abolish the farnesyltrnsferae activity responsible for prenylation of Ras proteins and the a-factor mating pheromone. Here we report that thefunction of RAM) antd RAM2 genme is required for the membrane laliation ofRas proteins and a-factor. The RAM2 gene was sequenced and can encode a 38-kDa protein.We examined tie functional interaction ofRAM2 andRAMf by expressing the genes in Escherchia colt. Extracts derived from an E. coil strain that coexpressed RAM] and RAM2 efficiently farnesylated a-factor peptide and Ras protein substrates. In contrast, extracts derived from E. colN strains that expressed either RAM gene alone were devoid of activity; however, when the latter extracts were mixed, protein farnesyltransferaSe activity was reconstituted. These results indicate that the yeast farnesyl-protein transferase is comprised of Raml and Ram2 polypeptides. Although Raml is a component of the enzyme, disruption of the RAM) gene in yeast was not lethal indicating that the Raml-Ram2 farnesyltserase is not essential for viability. In contrast, disruption of RAM2 was lethal, suggesting that Ram2 has an essential function in addition to its role with Raml in protein farnesylation.The post-translational modification of proteins by the covalent attachment of isoprenoid groups plays an important role in the membrane targeting of various proteins (1-5). Three classes of prenylated proteins in eukaryotic cells have been described. The first class, represented by certain fungal mating pheromones, Ras proteins, and nuclear lamins, is initially synthesized with a C-terminal CAAX sequence, where X = Ser, Cys, Met, or Ala, and is modified by thioether linkage of a C15 farnesyl group to the cysteine residue (6-9). The second class of prenylated proteins, represented by the y subunits of certain heterotrimeric G proteins and various Ras-like proteins, is initially synthesized with different C-terminal CAAX sequences, in which X = Leu or Phe, and is modified by the attachment of a C20 geranylgeranyl group to the cysteine residue (10-12). Members of both of these classes of prenylated proteins are subsequently processed by proteolytic removal of the three terminal amino acids and methylation of the newly exposed carboxyl group of the prenyl-cysteine (6, 10-15). The third class of prenylated proteins, represented by the Yptl/Sec4 (Rab) family of Ras-like GTPases that terminate with the sequence CC or CXC, is also geranylgeranylated at a C-terminal cysteine residue(s) (16)(17)(18).

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BackgroundModification of nucleosides on transfer RNA (tRNA) is important either for correct mRNA decoding process or for tRNA structural stabilization. Nucleoside methylations catalyzed by MTase (methyltransferase) are the most common type among all tRNA nucleoside modifications. Although tRNA modified nucleosides and modification enzymes have been extensively studied in prokaryotic systems, similar research remains preliminary in higher plants, especially in crop species, such as rice (Oryza sativa). Rice is a monocot model plant as well as an important cereal crop, and stress tolerance and yield are of great importance for rice breeding.ResultsIn this study, we investigated how the composition and abundance of tRNA modified nucleosides could change in response to drought, salt and cold stress, as well as in different tissues during the whole growth season in two model plants–O. sativa and Arabidopsis thaliana. Twenty two and 20 MTase candidate genes were identified in rice and Arabidopsis, respectively, by protein sequence homology and conserved domain analysis. Four methylated nucleosides, Am, Cm, m1A and m7G, were found to be very important in stress response both in rice and Arabidopsis. Additionally, three nucleosides,Gm, m5U and m5C, were involved in plant development. Hierarchical clustering analysis revealed consistency on Am, Cm, m1A and m7G MTase candidate genes, and the abundance of the corresponding nucleoside under stress conditions. The same is true for Gm, m5U and m5C modifications and corresponding methylation genes in different tissues during different developmental stages.ConclusionsWe identified candidate genes for various tRNA modified nucleosides in rice and Arabidopsis, especially on MTases for methylated nucleosides. Based on bioinformatics analysis, nucleoside abundance assessments and gene expression profiling, we propose four methylated nucleosides (Am, Cm, m1A and m7G) that are critical for stress response in rice and Arabidopsis, and three methylated nucleosides (Gm, m5U and m5C) that might be important during development.Electronic supplementary materialThe online version of this article (10.1186/s12870-017-1206-0) contains supplementary material, which is available to authorized users.

The vast majority of lepidopterans, about 90%, are moths. Some moths, particularly their caterpillars, are major agricultural and forestry pests in many parts of the world. However, some other members of moths, such as the silkworm Bombyx mori, are famous for their economic value. Fire et al. in 1998 initially found that exogenous double-stranded RNA (dsRNA) can silence the homolog endogenous mRNA in organisms, which is called RNA interference (RNAi). Soon after, the RNAi technique proved to be very promising not only in gene function determination but also in pest control. However, later studies demonstrate that performing RNAi in moths is not as straightforward as shown in other insect taxa. Nevertheless, since 2007, especially after 2010, an increasing number of reports have been published that describe successful RNAi experiments in different moth species either on gene function analysis or on pest management exploration. So far, more than 100 peer-reviewed papers have reported successful RNAi experiments in moths, covering 10 families and 25 species. By using classic and novel dsRNA delivery methods, these studies effectively silence the expression of various target genes and determine their function in larval development, reproduction, immunology, resistance against chemicals, and other biological processes. In addition, a number of laboratory and field trials have demonstrated that RNAi is also a potential strategy for moth pest management. In this review, therefore, we summarize and discuss the mechanisms and applications of the RNAi technique in moths by focusing on recent progresses.