Initial Characterization and Expression Pattern Analysis of Tobacco (Nicotiana Tabacum) 2-Hydroxyisoflavanone Dehydratasedase Gene

The complete mRNA sequence of one tobacco (nicotiana tabacum) gene—2-hydroxyisoflavanone dehydratasedase, was amplified using the rapid amplification of cDNA ends methods based on one tobacco EST. The full-length tobacco 2-hydroxyisoflavanone dehydratasedase gene mRNA was 1,278bp containing a 966 bp open reading frame, which encodes a protein of 321 amino acids. Sequence analysis revealed that the 2-hydroxyisoflavanone dehydratasedase of tobacco shares high homology with the 2-hydroxyisoflavanone dehydratasedase of nicotiana tomentosiformis(99%), capsicum annuum(78%), potato(75%), lycopersicon pennellii(73%) and lycopersicon esculentum(72%). BLAST analysis within the tobacco high throughout genomic sequences database revealed that this gene has no intron and is a single exon gene. Results also showed that tobacco 2-hydroxyisoflavanone dehydratasedase gene has a closer genetic relationship with the 2-hydroxyisoflavanone dehydratasedase gene of nicotiana tomentosiformis. Tissue expression profile analysis revealed that the tobacco 2-hydroxyisoflavanone dehydratasedase gene was highly expressed in leaf and flower, but moderately expressed in root and stem. Our experiment established the foundation for further research on this tobacco gene.

The evolution of the huntingtin-associated protein 40 (HAP40) in conjunction with huntingtin

Background The huntingtin-associated protein 40 (HAP40) abundantly interacts with huntingtin (HTT), the protein that is altered in Huntington’s disease (HD). Therefore, we analysed the evolution of HAP40 and its interaction with HTT. Results We found that in amniotes HAP40 is encoded by a single-exon gene, whereas in all other organisms it is expressed from multi-exon genes. HAP40 co-occurs with HTT in unikonts, including filastereans such as Capsaspora owczarzaki and the amoebozoan Dictyostelium discoideum, but both proteins are absent from fungi. Outside unikonts, a few species, such as the free-living amoeboflagellate Naegleria gruberi, contain putative HTT and HAP40 orthologs. Biochemically we show that the interaction between HTT and HAP40 extends to fish, and bioinformatic analyses provide evidence for evolutionary conservation of this interaction. The closest homologue of HAP40 in current protein databases is the family of soluble N-ethylmaleimide-sensitive factor attachment proteins (SNAPs). Conclusion Our results indicate that the transition from a multi-exon to a single-exon gene appears to have taken place by retroposition during the divergence of amphibians and amniotes, followed by the loss of the parental multi-exon gene. Furthermore, it appears that the two proteins probably originated at the root of eukaryotes. Conservation of the interaction between HAP40 and HTT and their likely coevolution strongly indicate functional importance of this interaction.

The mouse Sry locus harbors a cryptic exon that is essential for male sex determination

The mammalian sex-determining gene Sry induces male development. Since its discovery 30 years ago, Sry has been believed to be a single-exon gene. Here, we identified a cryptic second exon of mouse Sry and a corresponding two-exon type Sry (Sry-T) transcript. XY mice lacking Sry-T were sex-reversed, and ectopic expression of Sry-T in XX mice induced male development. Sry-T messenger RNA is expressed similarly to that of canonical single-exon type Sry (Sry-S), but SRY-T protein is expressed predominantly because of the absence of a degron in the C terminus of SRY-S. Sry exon2 appears to have evolved recently in mice through acquisition of a retrotransposon-derived coding sequence to replace the degron. Our findings suggest that in nature, SRY-T, not SRY-S, is the bona fide testis-determining factor.