| 1. |
- Elsik, Christine G., et al.
(författare)
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The Genome Sequence of Taurine Cattle : A Window to Ruminant Biology and Evolution
- 2009
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 324:5926, s. 522-528
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Tidskriftsartikel (refereegranskat)abstract
- To understand the biology and evolution of ruminants, the cattle genome was sequenced to about sevenfold coverage. The cattle genome contains a minimum of 22,000 genes, with a core set of 14,345 orthologs shared among seven mammalian species of which 1217 are absent or undetected in noneutherian (marsupial or monotreme) genomes. Cattle-specific evolutionary breakpoint regions in chromosomes have a higher density of segmental duplications, enrichment of repetitive elements, and species-specific variations in genes associated with lactation and immune responsiveness. Genes involved in metabolism are generally highly conserved, although five metabolic genes are deleted or extensively diverged from their human orthologs. The cattle genome sequence thus provides a resource for understanding mammalian evolution and accelerating livestock genetic improvement for milk and meat production.
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| 2. |
- Plan, Manuel R, et al.
(författare)
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Structural and biochemical characteristics of the cyclotide kalata B5 from Oldenlandia affinis.
- 2010
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Ingår i: Biopolymers. - : Wiley. - 0006-3525 .- 1097-0282. ; 94:5, Sp. Iss. SI, s. 647-658
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Tidskriftsartikel (refereegranskat)abstract
- Cyclotides are a large family of plant-derived proteins typified by their head-to-tail cyclic backbone and knotted arrangement of three disulfide bonds. Although they display a diverse range of biological activities, their native function is thought to be plant defense. Here we characterized the expression, three-dimensional structure, and hemolytic activity of the cyclotide kalata B5 from the African plant Oldenlandia affinis. Kalata B5 shows an interesting seasonal variation in its expression and can only be isolated during certain times of the year, when the plant is flowering. It displays a typical tightly folded cyclic cystine knot structure. A range of pH and temperature titrations reveal that a conserved glutamic acid in loop 1 of the structure forms a key hydrogen bond network, similar to that reported previously for other cyclotides. However, specific line broadening in the NMR spectra of kalata B5 suggests that the hydrogen bonding network in this peptide is less rigid than in other cyclotides. Notably, the pK(a) of Glu6 of 4.5 is higher than the values for other cyclotides studied so far, which range from 3.0 to 4.0, providing a further indication of a weaker hydrogen bond network. Kalata B5 has only moderate hemolytic activity compared with other highly expressed cyclotides, and this reduced activity probably reflects its more flexible structure. As is the case with other cyclotides, kalata B5 has an exposed hydrophobic region on its surface, supporting suggestions that this hydrophobic patch is a key feature for membrane binding and biological activity of cyclotides. (c) 2010 Wiley Periodicals, Inc. Biopolymers (Pept Sci), 2010.
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| 3. |
- Simonsen, Shane M, et al.
(författare)
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A continent of plant defense peptide diversity : cyclotides in Australian Hybanthus (Violaceae)
- 2005
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Ingår i: The Plant Cell. - : Oxford University Press (OUP). - 1040-4651 .- 1532-298X. ; 17:11, s. 3176-3189
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Tidskriftsartikel (refereegranskat)abstract
- Cyclotides are plant-derived miniproteins that have the unusual features of a head-to-tail cyclized peptide backbone and a knotted arrangement of disulfide bonds. It had been postulated that they might be an especially large family of host defense agents, but this had not yet been tested by field data on cyclotide variation in wild plant populations. In this study, we sampled Australian Hybanthus (Violaceae) to gain an insight into the level of variation within populations, within species, and between species. A wealth of cyclotide diversity was discovered: at least 246 new cyclotides are present in the 11 species sampled, and 26 novel sequences were characterized. A new approach to the discovery of cyclotide sequences was developed based on the identification of a conserved sequence within a signal sequence in cyclotide precursors. The number of cyclotides in the Violaceae is now estimated to be >9000. Cyclotide physicochemical profiles were shown to be a useful taxonomic feature that reflected species and their morphological relationships. The novel sequences provided substantial insight into the tolerance of the cystine knot framework in cyclotides to amino acid substitutions and will facilitate protein engineering applications of this framework.
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