| 1. |
- Finn, Robert D, et al.
(författare)
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Pfam : clans, web tools and services.
- 2006
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Ingår i: Nucleic Acids Res. - : Oxford University Press (OUP). - 1362-4962 .- 0305-1048. ; 34:Database issue, s. D247-51
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Tidskriftsartikel (refereegranskat)
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| 2. |
- Forslund, Kristoffer, et al.
(författare)
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Domain tree-based analysis of protein architecture evolution
- 2008
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Ingår i: Molecular biology and evolution. - : Oxford University Press (OUP). - 0737-4038 .- 1537-1719. ; 25:2, s. 254-264
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the dynamics behind domain architecture evolution is of great importance to unravel the functions of proteins. Complex architectures have been created throughout evolution by rearrangement and duplication events. An interesting question is how many times a particular architecture has been created, a form of convergent evolution or domain architecture reinvention. Previous studies have approached this issue by comparing architectures found in different species. We wanted to achieve a finer-grained analysis by reconstructing protein architectures on complete domain trees. The prevalence of domain architecture reinvention in 96 genomes was investigated with a novel domain tree-based method that uses maximum parsimony for inferring ancestral protein architectures. Domain architectures were taken from Pfam. To ensure robustness, we applied the method to bootstrap trees and only considered results with strong statistical support. We detected multiple origins for 12.4% of the scored architectures. In a much smaller data set, the subset of completely domain-assigned proteins, the figure was 5.6%. These results indicate that domain architecture reinvention is a much more common phenomenon than previously thought. We also determined which domains are most frequent in multiply created architectures and assessed whether specific functions could be attributed to them. However, no strong functional bias was found in architectures with multiple origins.
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| 3. |
- Hollich, Volker
(författare)
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Orthology and protein domain architecture evolution
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A major factor behind protein evolution is the ability of proteins to evolve new domain architectures that encode new functions. Protein domains are widely considered to constitute the "atoms" of protein chains, acting as building blocks of proteins as well as evolutionary units. A small number of domains are found in many different domain combinations, while the majority of domains co-occur with very few types of other domains. Domain architectures are not necessarily created once only during evolution. Cases of convergent evolution show how a favourable domain architecture has evolved multiple times independently. A basic concept for understanding evolution on gene level is orthology. Two genes are orthologous if they have evolved from the same gene in the last common ancestor of the species and have thus been created by a speciation event. Paralogous genes result from a duplication event that produced two gene copies within the same species.The concept of orthology can be transferred from genes to protein domains and utilised to explain recombination of protein domains and the evolution of domain architectures. The focus of this work is to augment the understanding of domain architecture evolution and its functional implications. We have examined, evaluated and improved existing methods as well as developed new approaches. The concept of orthology plays a major role in this work. Orthology is often inferred from phylogenetic trees that are based on pairwise distance estimations of protein sequences. The Scoredist protein sequence distance estimator has been developed as one part of this thesis. It combines robustness with low computational complexity and can be calibrated towards various evolutionary models. Accurate phylogenetic trees are crucial for many applications, hence the appropriate tree reconstruction algorithm should be chosen with care. The strengths and weaknesses of many current tree reconstruction algorithms were assessed, and findings underscore the value of the Scoredist estimator. The Pfam protein families database comprises a large number of protein families and domains. As part of this thesis it has been enhanced by search and query tools, such as PfamAlyzer or the browser-based domain query, that can be applied on whole domain architectures instead of individual domains only. We have developed a Maximum Parsimony algorithm for the prediction of ancestral domain architectures. In contrast to previous approaches, it employs gene trees rather than species trees. The algorithm was a starting point for an extensive study of the domain architectures present in Pfam for 50 completely sequenced species. Sampling widely across the kingdoms of life, the study sought to find and analyse cases where a domain architecture had been created multiple times. The algorithm proved robust to potential biases from horizontal gene transfer. Convergent evolution of domain architectures was found more frequently than by previous approaches. No strong biases driving convergent evolution were found. It therefore seems to be a random process in much the same way evolution through duplication and recombination, yet less frequent.
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| 4. |
- Hollich, Volker, et al.
(författare)
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PfamAlyzer : domain-centric homology search
- 2007
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Ingår i: Bioinformatics. - : Oxford University Press (OUP). - 1367-4803 .- 1367-4811 .- 1460-2059. ; 23:24, s. 3382-3383
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Tidskriftsartikel (refereegranskat)abstract
- PfamAlyzer is a Java applet that enables exploration of Pfam domain architectures using a user-friendly graphical interface. It can search the UniProt protein database for a domain pattern. Domain patterns similar to the query are presented graphically by PfamAlyzer either in a ranked list or pinned to the tree of life. Such domain-centric homology search can assist identification of distant homologs with shared domain architecture.
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