The automated Galaxy-SynBioCAD pipeline for synthetic biology design and engineering.

Here we introduce the Galaxy-SynBioCAD portal, a toolshed for synthetic biology, metabolic engineering, and industrial biotechnology. The tools and workflows currently shared on the portal enables one to build libraries of strains producing desired chemical targets covering an end-to-end metabolic pathway design and engineering process from the selection of strains and targets, the design of DNA parts to be assembled, to the generation of scripts driving liquid handlers for plasmid assembly and strain transformations. Standard formats like SBML and SBOL are used throughout to enforce the compatibility of the tools. In a study carried out at four different sites, we illustrate the link between pathway design and engineering with the building of a library of E. coli lycopene-producing strains. We also benchmark our workflows on literature and expert validated pathways. Overall, we find an 83% success rate in retrieving the validated pathways among the top 10 pathways generated by the workflows.

XTMS: pathway design in an eXTended metabolic space.

As metabolic engineering and synthetic biology progress toward reaching the goal of a more sustainable use of biological resources, the need of increasing the number of value-added chemicals that can be produced in industrial organisms becomes more imperative. Exploring, however, the vast possibility of pathways amenable to engineering through heterologous genes expression in a chassis organism is complex and unattainable manually. Here, we present XTMS, a web-based pathway analysis platform available at http://xtms.issb.genopole.fr, which provides full access to the set of pathways that can be imported into a chassis organism such as Escherichia coli through the application of an Extended Metabolic Space modeling framework. The XTMS approach consists on determining the set of biochemical transformations that can potentially be processed in vivo as modeled by molecular signatures, a specific coding system for derivation of reaction rules for metabolic reactions and enumeration of all the corresponding substrates and products. Most promising routes are described in terms of metabolite exchange, maximum allowable pathway yield, toxicity and enzyme efficiency. By answering such critical design points, XTMS not only paves the road toward the rationalization of metabolic engineering, but also opens new processing possibilities for non-natural metabolites and novel enzymatic transformations.

Genomic organization of evolutionarily correlated genes in bacteria: limits and strategies.

The need for efficient molecular interplay in time and space within a cell imposes strong constraints that could be partially relaxed if relative gene positions along chromosomes were appropriate. Comparative genomics studies have demonstrated the short-scale conservation of gene proximity along bacterial chromosomes. Additionally, the long-range periodic positioning of evolutionarily correlated genes within Escherichia coli has recently been highlighted. To gain further insight into these different genetic organizations, we examined the compromise between chromosomal proximity and periodicity for all available eubacterial genomes by evaluating groups of evolutionarily correlated genes from a benchmark data set. In enterobacteria, strict chromosomal proximity is found to be limited to groups under 20 genes, whereas periodicity is significant in all groups over 50. The E. coli K12 genome bears 511 periodic genes (12% of the genome), whose orthologs are found to be periodic in all eubacterial phyla. These periodic genes predominantly function in macromolecular synthesis and spatial organization of cellular components. They are enriched in essential and housekeeping genes and tend to often be constitutively expressed. On this basis, it is argued that chromosomal proximity and periodicity are ubiquitous complementary genomic strategies that favor the build-up of local concentrations of co-functional molecules. In particular, the periodic layout may facilitate chromosome folding to spatially organize the construction of major cell components. The transition at 20 genes is reminiscent of the size of the longest operons and of topological microdomains. The range for which DNA neighborhood optimizes biochemical interactions might therefore be defined by DNA topology.

Periodic pattern detection in sparse boolean sequences.

BACKGROUND: The specific position of functionally related genes along the DNA has been shown to reflect the interplay between chromosome structure and genetic regulation. By investigating the statistical properties of the distances separating such genes, several studies have highlighted various periodic trends. In many cases, however, groups built up from co-functional or co-regulated genes are small and contain wrong information (data contamination) so that the statistics is poorly exploitable. In addition, gene positions are not expected to satisfy a perfectly ordered pattern along the DNA. Within this scope, we present an algorithm that aims to highlight periodic patterns in sparse boolean sequences, i.e. sequences of the type 010011011010... where the ratio of the number of 1's (denoting here the transcription start of a gene) to 0's is small. RESULTS: The algorithm is particularly robust with respect to strong signal distortions such as the addition of 1's at arbitrary positions (contaminated data), the deletion of existing 1's in the sequence (missing data) and the presence of disorder in the position of the 1's (noise). This robustness property stems from an appropriate exploitation of the remarkable alignment properties of periodic points in solenoidal coordinates. CONCLUSIONS: The efficiency of the algorithm is demonstrated in situations where standard Fourier-based spectral methods are poorly adapted. We also show how the proposed framework allows to identify the 1's that participate in the periodic trends, i.e. how the framework allows to allocate a positional score to genes, in the same spirit of the sequence score. The software is available for public use at http://www.issb.genopole.fr/MEGA/Softwares/iSSB_SolenoidalApplication.zip.

The bacterial Tn9 chloramphenicol resistance gene: an attractive DNA segment for Mos1 mariner insertions.

The eukaryotic mariner transposons are currently thought to have no sequence specificity for integration other than to insert within a TA contained in a degenerated [TA](1-4) tract, either in vitro or in vivo. We have investigated the properties of a suspected hotspot for the integration of the mariner Mos1 element, namely the Tn9 cat gene that encodes a chloramphenicol acetyl transferase. Using in vitro and bacterial transposition assays, we confirmed that the cat gene is a preferential target for MOS1 integration, whatever its sequence environment, copy number or chromosomal locus. We also observed that its presence increases transposition rates both in vitro and in bacterial assays. The structural and sequence features that constitute the attractiveness of cat were also investigated. We first demonstrated that supercoiling is essential for the cat gene to be a hot spot. In contrast to the situation for Tc1-like elements, DNA curvature and bendability were not found to affect integration target preferences. We found that Mos1 integrations do not occur randomly along the cat gene. All TA dinucleotides that are preferred for integration were found within either TATA or TA x TA motifs. However, these motifs are not sufficient to constitute an attractive dinucleotide, since four TATA and TA x TA sites are cold spots.

ADN-Viewer: a 3D approach for bioinformatic analyses of large DNA sequences.

Most of biologists work on textual DNA sequences that are limited to the linear representation of DNA. In this paper, we address the potential offered by Virtual Reality for 3D modeling and immersive visualization of large genomic sequences. The representation of the 3D structure of naked DNA allows biologists to observe and analyze genomes in an interactive way at different levels. We developed a powerful software platform that provides a new point of view for sequences analysis: ADNViewer. Nevertheless, a classical eukaryotic chromosome of 40 million base pairs requires about 6 Gbytes of 3D data. In order to manage these huge amounts of data in real-time, we designed various scene management algorithms and immersive human-computer interaction for user-friendly data exploration. In addition, one bioinformatics study scenario is proposed.

A 3D pattern matching algorithm for DNA sequences.

MOTIVATION: Biologists usually work with textual DNA sequences (succession of A, C, G and T). This representation allows biologists to study the syntax and other linguistic properties of DNA sequences. Nevertheless, such a linear coding offers only a local and a one-dimensional vision of the molecule. The 3D structure of DNA is known to be very important in many essential biological mechanisms. By using 3D conformation models, one is able to construct a 3D trajectory of a naked DNA molecule. From the various studies that we performed, it turned out that two very different textual DNA sequences could have similar 3D structures. RESULTS: In this article, we address a new research work on 3D pattern matching for DNA sequences. The aim of this work is to enhance conventional pattern matching analyses with 3D-augmented criteria. We have developed an algorithm, based on 3D trajectories, which compares angles formed by these trajectories and thus quantifies the difference between two 3D DNA sequences. This analysis performs from a global scale to al local one. AVAILABILITY: Available on request from the authors.

Representation and processing of complex DNA spatial architecture and its annotated genomic content.

This paper presents a new general approach for the spatial representation and visualization of DNA molecule and its annotated information. This approach is based on a biological 3D model that predicts the complex spatial trajectory of huge naked DNA. With such modeling, a global vision of the sequence is possible, which is different and complementary to other representations as textual, linguistics or syntactic ones. The DNA is well known as a three-dimensional structure. Whereas, the spatial information plays a great part during its evolution and its interaction with the other biological elements This work will motivate investigations in order to launch new bioinformatics studies for the analysis of the spatial architecture of the genome. Besides, in order to obtain a friendly interactive visualization, a powerful graphic modeling is proposed including DNA complex trajectory management and its annotated-based content structuring. The paper describes spatial architecture modeling, with consideration of both biological and computational constraints. This work is implemented through a powerful graphic software tool, named ADN-Viewer. Several examples of visualization are shown for various organisms and biological elements.