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Erich Bornberg-Bauer

Publications and source records attributed to Erich Bornberg-Bauer.

16 recordsLinked to original sources
PubMed2025

Expression of De Novo Open Reading Frames in Natural Populations of Drosophila melanogaster.

De novo genes, which originate from noncoding DNA, are known to have a high rate of turnover over short evolutionary timescales, such as within a species. Thus, their expression is often lineage- or genetic background-specific. However, little is known about their levels and breadth of expression as populations of a species diverge. In this study, we utilized publicly available RNA-seq data to examine the expression of newly evolved open reading frames (neORFs) in comparison to non- and protein-coding genes in Drosophila melanogaster populations from the derived species range in Europe and the ancestral range in sub-Saharan Africa. Our datasets included two adult tissue types as well as whole bodies at two temperatures for both sexes and three larval/prepupal developmental stages in a single tissue and sex, which allowed us to examine neORF expression and divergence across multiple sample types as well as sex and population. We detected a relatively large proportion (approximately 50%) of annotated neORFs as expressed in the population samples, with neORFs often showing greater expression divergence between populations than non- or protein-coding genes. However, differential expression of neORFs between populations tended to occur in a sample type-specific manner. On the other hand, neORFs displayed less sex-biased expression than the other two gene classes, with the majority of sex-biased neORFs detected in whole bodies, which may be attributable to the presence of the gonads. We also found that neORFs shared among multiple lines in the original set of inbred lines in which they were first detected were more likely to be both expressed and differentially expressed in the new population samples, suggesting that neORFs at a higher frequency (i.e. present in more individuals) within a species are more likely to be functional.

Animals↗
PubMed2006

Evidence of interaction network evolution by whole-genome duplications: a case study in MADS-box proteins.

Recent investigations on metazoan transcription factors (TFs) indicate that single-gene duplication events and the gain and loss of protein domains are 2 crucial factors in shaping their protein-protein interaction networks. Plant genomes, on the other hand, have a history of polyploidy and whole-genome duplications (WGDs), and thus, their study helps to understand whether WGDs have also had a significant influence on protein network evolution. Here we investigate the evolution of the interaction network in the well-studied MADS domain MIKC-type proteins, a TF family which plays an important role in both the vegetative and the reproductive phases of plant life. We combine phylogenetic reconstruction, protein domain analysis, and interaction data from different species. We show that, unlike previously analyzed interaction networks, the MIKC-type protein network displays a characteristic topology, with overall high inter-subfamily connectivity, shared interactors between paralogs, and conservation of interaction patterns across species. The evaluation of the number of MIKC-type proteins at key time points throughout the evolution of land plants in the lineage leading to Arabidopsis suggested that most duplicates were retained after each round of WGD. We provide evidence that an initial network, formed by 9-11 homodimerizing proteins interacting with each other, existed in the common ancestor of all seed plants. This basic structure has been conserved after each round of WGD, adding layers of paralogs with similar interaction patterns. We thus present the first model where we can show that a network of eukaryotic TFs has evolved via rounds of WGD. Furthermore, we found that in subfamilies in which the K domain is most diverged, the interactions with other subfamilies have been largely lost. We discuss the possibility that such a high proportion of genes were retained after each WGD because of their capacity to form higher order complexes involving proteins from different subfamilies. The simultaneous duplications allowed for the conservation of the quantitative balance between the constituents and facilitated sub- and neofunctionalization through differential expression of whole units.

Computational Biology↗
PubMed2006

Reduction/oxidation-phosphorylation control of DNA binding in the bZIP dimerization network.

BACKGROUND: bZIPs are transcription factors that are found throughout the eukarya from fungi to flowering plants and mammals. They contain highly conserved basic region (BR) and leucine zipper (LZ) domains and often function as environmental sensors. Specifically, bZIPs frequently have a role in mediating the response to oxidative stress, a crucial environmental signal that needs to be transduced to the gene regulatory network. RESULTS: Based on sequence comparisons and experimental data on a number of important bZIP transcription factors, we predict which bZIPs are under redox control and which are regulated via protein phosphorylation. By integrating genomic, phylogenetic and functional data from the literature, we then propose a link between oxidative stress and the choice of interaction partners for the bZIP proteins. CONCLUSION: This integration permits the bZIP dimerization network to be interpreted in functional terms, especially in the context of the role of bZIP proteins in the response to environmental stress. This analysis demonstrates the importance of abiotic factors in shaping regulatory networks.

Amino Acid Sequence↗
PubMed2006

Evolution of circular permutations in multidomain proteins.

Modular rearrangements play an important role in protein evolution. Functional modules, often tantamount to structural domains or smaller fragments, are in many cases well conserved but reoccur in a different order and across many protein families. The underlying genetic mechanisms are gene duplication, fusion, and loss of sequence fragments. As a consequence, the sequential order of domains can be inverted, leading to what is known as circularly permutated proteins. Using a recently developed algorithm, we have identified a large number of such rearrangements and analyzed their evolutionary history. We searched for examples which have arisen by one of the three postulated mechanisms: independent fusion/fission, "duplication/deletion," and plasmid-mediated "cut and paste." We conclude that all three mechanisms can be observed, with the independent fusion/fission being the most frequent. This can be partly attributed to highly mobile domains. Duplication/deletion has been found in modular proteins such as peptide synthases.

Archaea↗
PubMed2006

Domain deletions and substitutions in the modular protein evolution.

The main mechanisms shaping the modular evolution of proteins are gene duplication, fusion and fission, recombination and loss of fragments. While a large body of research has focused on duplications and fusions, we concentrated, in this study, on how domains are lost. We investigated motif databases and introduced a measure of protein similarity that is based on domain arrangements. Proteins are represented as strings of domains and comparison was based on the classic dynamic alignment scheme. We found that domain losses and duplications were more frequent at the ends of proteins. We showed that losses can be explained by the introduction of start and stop codons which render the terminal domains nonfunctional, such that further shortening, until the whole domain is lost, is not evolutionarily selected against. We demonstrated that domains which also occur as single-domain proteins are less likely to be lost at the N terminus and in the middle, than at the C terminus. We conclude that fission/fusion events with single-domain proteins occur mostly at the C terminus. We found that domain substitutions are rare, in particular in the middle of proteins. We also showed that many cases of substitutions or losses result from erroneous annotations, but we were also able to find courses of evolutionary events where domains vanish over time. This is explained by a case study on the bacterial formate dehydrogenases.

Amino Acid Motifs↗
PubMed2005

Rapid motif-based prediction of circular permutations in multi-domain proteins.

MOTIVATION: Rearrangements of protein domains and motifs such as swaps and circular permutations (CPs) can produce erroneous results in searching sequence databases when using traditional methods based on linear sequence alignments. Circular permutations are also of biological relevance because they can help to better understand both protein evolution and functionality. RESULTS: We have developed an algorithm, RASPODOM, which is based on the classical recursive alignment scheme. Sequences are represented as strings of domains taken from precompiled resources of domain (motif) databases such as ProDom. The algorithm works several orders of magnitude faster than a reimplementation of the existing CP detection algorithm working on strings of amino acids, produces virtually no false positives and allows the discrimination of true CPs from 'intermediate' CPs (iCPs). Several true CPs which have not been reported in literature so far could be identified from Swiss-Prot/TrEMBL within minutes.

Algorithms↗
PubMed2005

Phylogenetic profiling of protein interaction networks in eukaryotic transcription factors reveals focal proteins being ancestral to hubs.

The combination of genomic, proteomic and other data, enables to reconstruct the evolution of complex cellular units thus transcending the more reductionistic view of traditional molecular phylogeny. However, most models which try to investigate the evolution of protein interaction networks so far are based on the analysis of their global statistical properties, such as their scale-free behaviour. We have investigated phylogenies of three families of ancient eukaryotic transcription factors for which fairly reliable interaction data are available. For all three families, bZIP, bHLH and NR (nuclear receptors), we find that homo-dimerising proteins were probably the ancestors and that series of single gene duplications, in combination with domain-rearrangements, were the main driving force in establishing the basic network architecture. However, the overall scaling behaviour does not always precisely confer to some theoretical models on network evolution. In conclusion, new models which reflect the biological details of molecular evolution, need to be developed.

Basic-Leucine Zipper Transcription Factors↗
PubMed2005

Distribution of gibberellin biosynthetic genes and gibberellin production in the Gibberella fujikuroi species complex.

Gibberella fujikuroi is a species-rich monophyletic complex of at least nine sexually fertile biological species (mating populations, MP-A to MP-I) and more than 30 anamorphs in the genus Fusarium. They produce a variety of secondary metabolites, such as fumonisins, fusaproliferin, moniliformin, beauvericin, fusaric acid, and gibberellins (GAs), a group of plant hormones. In this study, we examined for the first time all nine sexually fertile species (MPs) and additional anamorphs within and outside the G. fujikuroi species complex for the presence of GA biosynthetic genes. So far, the ability to produce GAs was described only for Fusarium fujikuroi (G. fujikuroi MP-C), which contains seven clustered genes in the genome all participating in GA biosynthesis. We show that six other MPs (MPs B, D, E, F, G, and I) and most of the anamorphs within the species complex also contain the entire gene cluster, except for F. verticillioides (MP-A), and F. circinatum (MP-H), containing only parts of it. Despite the presence of the entire gene cluster in most of the species within the G. fujikuroi species complex, expression of GA biosynthetic genes and GA production were detected only in F. fujikuroi (MP-C) and one isolate of F. konzum (MP-I). We used two new molecular marker genes, P450-4 from the GA gene cluster, and cpr, encoding the highly conserved NADPH cytochrome P450 reductase to study phylogenetic relationships within the G. fujikuroi species complex. The molecular phylogenetic studies for both genes have revealed good agreement with phylogenetic trees inferred from other genes. Furthermore, we discuss the role and evolutionary origin of the GA biosynthetic gene cluster.

Gene Expression↗
PubMed2004

Comparing folding codes in simple heteropolymer models of protein evolutionary landscape: robustness of the superfunnel paradigm.

Understanding the evolution of biopolymers is a key element in rationalizing their structures and functions. Simple exact models (SEMs) are well-positioned to address general principles of evolution as they permit the exhaustive enumeration of both sequence and structure (conformational) spaces. The physics-based models of the complete mapping between genotypes and phenotypes afforded by SEMs have proven valuable for gaining insight into how adaptation and selection operate among large collections of sequences and structures. This study compares the properties of evolutionary landscapes of a variety of SEMs to delineate robust predictions and possible model-specific artifacts. Among the models studied, the ruggedness of evolutionary landscape is significantly model-dependent; those derived from more protein-like models appear to be smoother. We found that a common practice of restricting protein structure space to maximally compact lattice conformations results in (i.e., "designs in") many encodable (designable) structures that are not otherwise encodable in the corresponding unrestrained structure space. This discrepancy is especially severe for model potentials that seek to mimic the major role of hydrophobic interactions in protein folding. In general, restricting conformations to be maximally compact leads to larger changes in the model genotype-phenotype mapping than a moderate shifting of reference state energy of the model potential function to allow for more specific encoding via the "designing out" effects of repulsive interactions. Despite these variations, the superfunnel paradigm applies to all SEMs we have tested: For a majority of neutral nets across different models, there exists a funnel-like organization of native stabilities for the sequences in a neutral net encoding for the same structure, and the thermodynamically most stable sequence is also the most robust against mutation.

Biophysics↗
PubMed2004

Convergent evolution of gene networks by single-gene duplications in higher eukaryotes.

By combining phylogenetic, proteomic and structural information, we have elucidated the evolutionary driving forces for the gene-regulatory interaction networks of basic helix-loop-helix transcription factors. We infer that recurrent events of single-gene duplication and domain rearrangement repeatedly gave rise to distinct networks with almost identical hub-based topologies, and multiple activators and repressors. We thus provide the first empirical evidence for scale-free protein networks emerging through single-gene duplications, the dominant importance of molecular modularity in the bottom-up construction of complex biological entities, and the convergent evolution of networks.

Eukaryotic Cells↗
PubMed2002

Recombinatoric exploration of novel folded structures: a heteropolymer-based model of protein evolutionary landscapes.

The role of recombination in evolution is compared with that of point mutations (substitutions) in the context of a simple, polymer physics-based model mapping between sequence (genotype) and conformational (phenotype) spaces. Crossovers and point mutations of lattice chains with a hydrophobic polar code are investigated. Sequences encoding for a single ground-state conformation are considered viable and used as model proteins. Point mutations lead to diffusive walks on the evolutionary landscape, whereas crossovers can "tunnel" through barriers of diminished fitness. The degree to which crossovers allow for more efficient sequence and structural exploration depends on the relative rates of point mutations versus that of crossovers and the dispersion in fitness that characterizes the ruggedness of the evolutionary landscape. The probability that a crossover between a pair of viable sequences results in viable sequences is an order of magnitude higher than random, implying that a sequence's overall propensity to encode uniquely is embodied partially in local signals. Consistent with this observation, certain hydrophobicity patterns are significantly more favored than others among fragments (i.e., subsequences) of sequences that encode uniquely, and examples reminiscent of autonomous folding units in real proteins are found. The number of structures explored by both crossovers and point mutations is always substantially larger than that via point mutations alone, but the corresponding numbers of sequences explored can be comparable when the evolutionary landscape is rugged. Efficient structural exploration requires intermediate nonextreme ratios between point-mutation and crossover rates.

Biophysical Phenomena↗
PubMed2002

Conceptual data modelling for bioinformatics.

Current research in the biosciences depends heavily on the effective exploitation of huge amounts of data. These are in disparate formats, remotely dispersed, and based on the different vocabularies of various disciplines. Furthermore, data are often stored or distributed using formats that leave implicit many important features relating to the structure and semantics of the data. Conceptual data modelling involves the development of implementation-independent models that capture and make explicit the principal structural properties of data. Entities such as a biopolymer or a reaction, and their relations, eg catalyses, can be formalised using a conceptual data model. Conceptual models are implementation-independent and can be transformed in systematic ways for implementation using different platforms, eg traditional database management systems. This paper describes the basics of the most widely used conceptual modelling notations, the ER (entity-relationship) model and the class diagrams of the UML (unified modelling language), and illustrates their use through several examples from bioinformatics. In particular, models are presented for protein structures and motifs, and for genomic sequences.

Computational Biology↗
PubMed2002

TreeWiz: interactive exploration of huge trees.

MOTIVATION: The rapidly increasing amount and disparity of biological data requires interpretation at many levels of description. Human judgement and intuition are important because not all data can be automatically and comprehensively analyzed. Visualization of trees and substructures corresponding to certain features are often used to analyze phylogenies or taxonomies. Unfortunately, most existing tools do not cope with the size of current datasets, the required functionality, or both. RESULTS: We introduce a program for visualization of huge trees and also for the interactive exploration of their content. We have developed a range of new schemes which are tailored for biological problems. Users can get an overview, zoom in, filter out data and retrieve details from standard databases such as SWISS-PROT. Furthermore, it is possible to analyze the relationship between chosen leaf sets that are specified by common features on a second level of representation. On a PC (with approximately equal to 512 MB RAM), trees of up to several tens of thousands of leaves can be loaded and both rapidly and interactively explored. We demonstrate the use of this program for the analysis of the SYSTERS data set (which contains hierarchically clustered protein sequences) to which PFAM domains were added as features.

Classification↗
PubMed2002

Perspectives on protein evolution from simple exact models.

Understanding the evolution of biopolymers is important to rationalise the directed and undirected design of functional molecules. Large scale experiments or detailed computational studies are often impractical. Therefore, simple model systems, such as RNA secondary structure and lattice proteins have been adapted to study general statistical and topological features of genotype (sequence) to phenotype (structure) maps. We review findings from such models that address aspects of thermodynamic and mutational robustness, neutral evolution and recombination of proteins. We compare various modelling approaches, and discuss their generality, parameter dependency and experimental verifications of their predictions. The most striking observation is the universal emergence of neutral nets--sets of phenotypically identical genotypes that are interconnected by series of point mutations. However, fast adaptation by point mutations appears to be problematic for proteins. This may explain why proteins appear to be more specific while RNA is rather versatile. This could even be the reason why RNA had to evolve before proteins. Similar principles of biological organisation are reflected in sequence and structure databases of real proteins. Insights gained from modelling are useful for designing more efficient database organisation and search strategies.

Biopolymers↗