AUG_hairpin: prediction of a downstream secondary structure influencing the recognition of a translation start site

<p>Abstract</p> <p>Background</p> <p>The translation start site plays an important role in the control of translation efficiency of eukaryotic mRNAs. The recognition of the start AUG codon by eukaryotic ribosomes is considered to depend on its nucleotide context. However, the fraction of eukaryotic mRNAs with the start codon in a suboptimal context is relatively large. It may be expected that mRNA should possess some features providing efficient translation, including the proper recognition of a translation start site. It has been experimentally shown that a downstream hairpin located in certain positions with respect to start codon can compensate in part for the suboptimal AUG context and also increases translation from non-AUG initiation codons. Prediction of such a compensatory hairpin may be useful in the evaluation of eukaryotic mRNA translation properties.</p> <p>Results</p> <p>We evaluated interdependency between the start codon context and mRNA secondary structure at the CDS beginning: it was found that a suboptimal start codon context significantly correlated with higher base pairing probabilities at positions 13 – 17 of CDS of human and mouse mRNAs. It is likely that the downstream hairpins are used to enhance translation of some mammalian mRNAs <it>in vivo</it>. Thus, we have developed a tool, <it>AUG_hairpin</it>, to predict local stem-loop structures located within the defined region at the beginning of mRNA coding part. The implemented algorithm is based on the available published experimental data on the CDS-located stem-loop structures influencing the recognition of upstream start codons.</p> <p>Conclusion</p> <p>An occurrence of a potential secondary structure downstream of start AUG codon in a suboptimal context (or downstream of a potential non-AUG start codon) may provide researchers with a testable assumption on the presence of additional regulatory signal influencing mRNA translation initiation rate and the start codon choice. <it>AUG_hairpin</it>, which has a convenient Web-interface with adjustable parameters, will make such an evaluation easy and efficient.</p

Three Cycles of Continuous Propagation of a Severe PSTVd Strain NicTr-3 in Solanum lycopersicum cv. Rutgers Resulted in Its Attenuation and Very Mild Disease Symptoms in Potato

Potato spindle tuber viroid (PSTVd) is a small infectious non-coding circular RNA causing diseases of important crops, including tomato and potato. The symptoms vary from mild to severe depending on the viroid strain, the host plant variety, and the environmental conditions. The molecular mechanisms underlying the development of particular disease phenotypes remain elusive. The PSTVd strain NicTr-3 causes severe disease symptoms on Solanum lycopersicum cv. Rutgers and Solanum tuberosum cv. Colomba. It was found that after three cycles of propagation in tomato cv. Rutgers, infection of potato cv. Colomba with NicTr-3 resulted in very mild symptoms including smaller size of tubers and delayed leaf senescence. Sequence analysis of PSTVd clones isolated from tomato inoculum revealed the presence of mutated variants of genomic RNA. Transcriptome analysis carried out on leaves showed a considerable difference between infected and healthy plants at 14 dpi and 30 dpi. Interestingly, the response of potato plants to the attenuated PSTVd strain revealed a large number of DEGs associated with initiation of dormancy with a considerable increase in the vegetation period. The second vegetative generation (tuber-derived plantlets from control healthy and PSTVd-infected plants) was characterized by similar phenotypes and transcriptomes. Thus, here we describe a case of attenuation of a severe PSTVd strain after continuous propagation in tomato. It would be of interest to consider the attenuated viroid strains as a potential biocontrol agent or vaccine against this type of pathogenic RNA

Genetic control of anthocyanin pigmentation of potato tissues

Abstract Background The cultivated potato Solanum tuberosum L. is the fourth most important crop worldwide. Anthocyanins synthesis and accumulation in potato tissues are considered as one of important traits related to stress resistance and nutritional value. It is considered that the major regulatory gene for anthocyanin biosynthesis is R2R3 MYB-encoding gene StAN1. However, the genetic control of pigmentation of different potato tissues is substantially under investigated. The development of genetic markers for breeding of potato with specific pigmentation pattern remains an actual task. Results We investigated 36 potato varieties and hybrids with different pigmentation of tubers and leaves. Sequence organization of regulatory R2R3 MYB (StAN1, StMYBA1, StMYB113), bHLH (StbHLH1, StJAF13) and WD40 (StWD40) genes potentially controlling anthocyanin biosynthesis has been evaluated. The results demonstrated a high variability in the StAN1 third exon and promoter region with the exception for 35 bp, containing elements for the transcription start and activation of gene expression in roots. The analysis of transcriptional activity of genes coding R2R3 MYBs, bHLHs and WD40 transcriptional factors in leaves of eight potato genotypes with different anthocyanin pigmentation was performed. The results showed a relation between the gene expression level and plant pigmentation only for the StAN1 and StWD40 genes, while other studied genes had either strong expression in all varieties and hybrids (StMYBA1, StbHLH1 and StJAF13) or they were not expressed at all (StMYB113). Conclusions It was found that StAN1 is the major regulatory gene controlling potato anthocyanin synthesis. However, diagnostic markers developed for the functional StAN1 alleles (StAN1 777 and StAN1 816 ) can not be used efficiently for prediction of potato pigmentation patterns. It is likely that the sequence organization of StAN1 promoter is important for anthocyanin synthesis control and the development of additional diagnostic markers is necessary

Assembly and Analysis of Plastomes for 15 Potato Cultivars Grown in Russia

Chloroplasts are important organelles in a plant cell, having their own DNA (cpDNA), transmitted only through the female line, and performing the function of photosynthesis. The determination of chloroplast DNA is of interest in the study of the genetic diversity and phylogeny of potatoes, and of cytoplasmic sterility, as well as for applications in biotechnology and genetic engineering. Here, we reconstructed the complete plastomes of 15 S. tuberosum potato cultivars grown in Russia. Our analysis allowed us to determine the composition and location of genes for these plastid DNAs. It was shown that the plastid genome contains both highly and low-variable regions. The region at position 63,001–68,000 nt has the highest variability. We determined the types of cpDNA based on in silico approaches: 10 cultivars have cpDNA of the W-type and 5 cultivars have cpDNA of the T-type. The genetic diversity of the plastid DNA for these potato cultivars was analyzed alongside the previously reconstructed plastomes of South American accessions, European/North American commercial cultivars and potato cultivars bred in the Ural region. The results show that plastid DNAs of the same type form clusters by sequence similarity, in agreement with previous studies

Do Autism Spectrum and Autoimmune Disorders Share Predisposition Gene Signature Due to mTOR Signaling Pathway Controlling Expression?

Autism spectrum disorder (ASD) is characterized by uncommon genetic heterogeneity and a high heritability concurrently. Most autoimmune disorders (AID), similarly to ASD, are characterized by impressive genetic heterogeneity and heritability. We conducted gene-set analyses and revealed that 584 out of 992 genes (59%) included in a new release of the SFARI Gene database and 439 out of 871 AID-associated genes (50%) could be attributed to one of four groups: 1. FMRP (fragile X mental retardation protein) target genes, 2. mTOR signaling network genes, 3. mTOR-modulated genes, and 4. vitamin D3-sensitive genes. With the exception of FMRP targets, which are obviously associated with the direct involvement of local translation disturbance in the pathological mechanisms of ASD, the remaining categories are represented among AID genes in a very similar percentage as among ASD predisposition genes. Thus, mTOR signaling pathway genes make up 4% of ASD and 3% of AID genes, mTOR-modulated genes—31% of both ASD and AID genes, and vitamin D-sensitive genes—20% of ASD and 23% of AID genes. The network analysis revealed 3124 interactions between 528 out of 729 AID genes for the 0.7 cutoff, so the great majority (up to 67%) of AID genes are related to the mTOR signaling pathway directly or indirectly. Our present research and available published data allow us to hypothesize that both a certain part of ASD and AID comprise a connected set of disorders sharing a common aberrant pathway (mTOR signaling) rather than a vast set of different disorders. Furthermore, an immune subtype of the autism spectrum might be a specific type of autoimmune disorder with an early manifestation of a unique set of predominantly behavioral symptoms