30 research outputs found

    Initial sequencing and analysis of the human genome

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    The human genome holds an extraordinary trove of information about human development, physiology, medicine and evolution. Here we report the results of an international collaboration to produce and make freely available a draft sequence of the human genome. We also present an initial analysis of the data, describing some of the insights that can be gleaned from the sequence.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62798/1/409860a0.pd

    Finishing the euchromatic sequence of the human genome

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    The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

    A point mutation in Euglena gracilis chloroplast tRNA(Glu) uncouples protein and chlorophyll biosynthesis.

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    The universal precursor of tetrapyrrole pigments (e.g., chlorophylls and hemes) is 5-aminolevulinic acid (ALA), which in Euglena gracilis chloroplasts is derived via the two-step C5 pathway from glutamate charged to tRNA(Glu). The first enzyme in this pathway, Glu-tRNA reductase (GluTR) catalyzes the reduction of glutamyl-tRNA(Glu) (Glu-tRNA) to glutamate 1-semialdehyde (GSA) with the release of the uncharged tRNA(Glu). The second enzyme, GSA-2,1-aminomutase, converts GSA to ALA. tRNA(Glu) is a specific cofactor for the NADPH-dependent reduction by GluTR, an enzyme that recognizes the tRNA in a sequence-specific manner. This RNA is the normal tRNA(Glu), a dual-function molecule participating both in protein and in ALA and, hence, chlorophyll biosynthesis. A chlorophyll-deficient mutant of E. gracilis (Y9ZNalL) does not synthesize ALA from glutamate, although it contains GluTR and GSA-2,1-aminomutase activity. The tRNA(Glu) isolated from the mutant can still be acylated with glutamate in vitro and in vivo. Furthermore, it supports chloroplast protein synthesis; however, it is a poor substrate for GluTR. Sequence analysis of the tRNA and of its gene revealed a C56-->U mutation in the resulting gene product. C56 is therefore an important identity element for GluTR. Thus, a point mutation in the T loop of tRNA uncouples protein from chlorophyll biosynthesis
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