Evolutionary and functional relationships within the DJ1 superfamily

BACKGROUND: Inferences about protein function are often made based on sequence homology to other gene products of known activities. This approach is valuable for small families of conserved proteins but can be difficult to apply to large superfamilies of proteins with diverse function. In this study we looked at sequence homology between members of the DJ-1/ThiJ/PfpI superfamily, which includes a human protein of unclear function, DJ-1, associated with inherited Parkinson's disease. RESULTS: DJ-1 orthologs in a variety of eukaryotic species cluster together in a single group. The most closely related group is the bacterial ThiJ genes. These are kinases involved in the biosynthesis of thiamine, a function that has been dispensed with evolutionarily in most eukaryotes where thiamine is an essential nutrient. The similarity with other characterized members of the superfamily, including proteases, is more remote. This is congruent with the recently solved crystal structures that fail to demonstrate the presence of a catalytic triad required for protease activity. CONCLUSION: DJ-1 may have evolved from the bacterial gene encoding ThiJ kinase. However, as this function has been dispensed with in eukaryotes it appears that the gene has been co-opted for another function

Challenges in identifying cancer genes by analysis of exome sequencing data.

Massively parallel sequencing has permitted an unprecedented examination of the cancer exome, leading to predictions that all genes important to cancer will soon be identified by genetic analysis of tumours. To examine this potential, here we evaluate the ability of state-of-the-art sequence analysis methods to specifically recover known cancer genes. While some cancer genes are identified by analysis of recurrence, spatial clustering or predicted impact of somatic mutations, many remain undetected due to lack of power to discriminate driver mutations from the background mutational load (13-60% recall of cancer genes impacted by somatic single-nucleotide variants, depending on the method). Cancer genes not detected by mutation recurrence also tend to be missed by all types of exome analysis. Nonetheless, these genes are implicated by other experiments such as functional genetic screens and expression profiling. These challenges are only partially addressed by increasing sample size and will likely hold even as greater numbers of tumours are analysed

Intra-species sequence variability in 28s rRNA gene of Oesophagostomum venulosum isolated from goats of West Bengal, India

AbstractObjectiveTo identify genotypes of Oesophagostmum venulosum (O. venulosum) prevailing in West Bengal, India by comparing variation of nucleotide sequences among 28S rRNA.MethodsPCR amplification of partial segment of 28 S rRNA sequence and analysis of sequence amplified product by single strand conformation polymorphism (SSCP).ResultsTwo distinct conformers among male and female parasites were identified by PCR-SSCP analysis. Sequence analysis among conformers revealed the presence of five single nucleotide polymorphisms (SNP) in codon 64, 66, 86, 125 and 146. Secondary RNA prediction structure showed that out of 5 SNPs, 4 occurred at interior loop of RNA which confirmed evolutionary changes among isolates prevailing in this region.ConclusionsSNPs occured in different isolates of O. venulosum might influence critical changes in rRNA folding pattern which influence evolutionary changes among isolates