Florence Corpet

ProDom and ProDom-CG: tools for protein domain analysis and whole genome comparisons

ProDom contains all protein domain families automatically generated from the SWISS-PROT and TrEMBL sequence databases (http://www. toulouse.inra.fr/prodom.html ). ProDom-CG results from a similar domain analysis as applied to completed genomes (http://www.toulouse. inra.fr/prodomCG.html ). Recent improvements to the ProDom database and its server include: scaling up to include sequences from TrEMBL, addition of Pfam-A entries to the set of expert validated families, assignment of stable accession numbers, consistency indicators for domain families, domain arrangements of sub-families and links to Pfam-A.

The ProDom database of protein domain families

The ProDom database contains protein domain families generated from the SWISS-PROT database by automated sequence comparisons. It can be searched on the World Wide Web (http://protein.toulouse.inra. fr/prodom.html ) or by E-mail (prodom@toulouse.inra.fr) to study domain arrangements within known families or new proteins. Strong emphasis has been put on the graphical user interface which allows for interactive analysis of protein homology relationships. Recent improvements to the server include: ProDom search by keyword; links to PROSITE and PDB entries; more sensitive ProDom similarity search with BLAST or WU-BLAST; alignments of query sequences with homologous ProDom domain families; and links to the SWISS-MODEL server (http: //www.expasy.ch/swissmod/SWISS-MODEL.html ) for homology based 3-D domain modelling where possible.

Recent improvements of the ProDom database of protein domain families

The ProDom database contains protein domain families generated from the SWISS-PROT database by automated sequence comparisons. The current version was built with a new improved procedure based on recursive PSI-BLAST homology searches. ProDom can be searched on the World Wide Web to study domain arrangements within either known families or new proteins, with the help of a user-friendly graphical interface (http://www.toulouse.inra.fr/prodom.html). Recent improvements to the ProDom server include: ProDom queries under the SRS Sequence Retrieval System; links to the PredictProtein server; phylogenetic trees and condensed multiple alignments for a better representation of large domain families, with zooming in and out capabilities. In addition, a similar server was set up to display the outcome of whole genome domain analysis as applied to 17 completed microbial genomes (http://www.toulouse.inra.fr/prodomCG.html ).

Whole genome protein domain analysis using a new method for domain clustering

We present the outcome of a systematic analysis of protein domain shuffling in 17 completed microbial genomes. This analysis has been performed using MKDOM Version 2, a completely new version of the domain clustering program MKDOM based on PSI-BLAST recursive homology searches. It allows to delineate the most frequent protein domain building blocks, which domains are found specifically in Bacteria, Archaea or yeast, and which domains are shared between two or all three domains of life. The latter are good candidates as the basic protein building blocks underlying all forms of cellular life. Statistics of multi-domain proteins indicate that some organisms such as Bacillus subtilis or Mycobacterium tuberculosis contain an abnormally high number of large multi-domain proteins. We also provide examples of highly shuffled or circularly permutated domains. A WWW graphical interface has been made available to interactively browse domain arrangements of proteins in all 17 genomes, at http:@www.toulouse.inra.fr/prodomCG.html.

RNAlign program: alignment of RNA sequences using both primary and secondary structures

We have developed an algorithm and a computer program for aligning new RNA sequences with a bank of aligned homologous RNA sequences. Given a common folding structure for the bank, the program performs an alignment between the bank and a new sequence, optimal both in terms of primary and secondary structure. This method is useful to align sequences that present a common folding structure despite extensive divergence of their primary structures. It allows these preserved regions to be precisely distinguished from domains with more variable secondary structure. An optimal alignment of a sequence of length N with a bank of homologous sequences of length M is produced in O (M2N3) time and O(M2N2) space. For sequences that are too long for an algorithm of this complexity, a proposed strategy is to use a classical alignment (using only primary structure data) then improve it with the new algorithm in the regions where the bank stems are not aligned with possible stems in the new sequence. The algorithm has been implemented in Turbo Pascal on a PC, and has been used to align RNA sequences of eubacterial large ribosomal subunit.

Browsing protein families via the ‘Rich Family Description’ format

MOTIVATION Multiple alignments of protein sequences are the basis of structural and functional analysis of protein families. It is however difficult even for an expert biologist to comprehend an alignment of more than 50 to 100 homologous sequences. RESULTS This paper presents a browser for the analysis of multiple alignments of large numbers of protein sequences. Phylogenetic trees and consensus sequences are computed and used to summarise the alignments; these data are stored in a structure called Rich Family Description. Summary alignments and trees are displayed in HTML pages and can be developed or reduced by the user. This browser is used to display the ProDom domain families on the Web. Its zooming facilities allow extracting information from alignments of more than 1000 homologous sequences.

XDOM, a graphical tool to analyse domain arrangements in any set of protein sequences

MOTIVATION To extract the maximum possible information from a set of protein sequences, its modular organization must be known and clearly displayed. This is important both for structural and functional analysis. RESULTS This paper presents an algorithm and a graphical interface called XDOM which performs a systematic analysis of the modular organization of any set of protein sequences. The algorithm is an automatic method to identify putative domains from sequence comparisons. The graphical tool displays the proteins as a set of linked boxes, corresponding to its domains. The method has been tested on a family of bacterial proteins and on whole genomes. It is currently applied to the complete SWISS-PROT database to build the PRODOM database. AVAILABILITY XDOM is available free of charge by anonymous ftp:¿¿ftp://ftp.toulouse.inra.fr/pub/xdom¿ ¿. The ProDom database can be consulted at ¿¿http://protein.toulouse.inra.fr/prodom.html¿¿.

Lacker's model: control of follicular growth and ovulation in domestic species

AbstractLacker (1981) and Lacker & Akin (1988) developed a mathematical model of follicular maturation and ovulation; this model of only four parameters accounts for a large number of results obtained over the past decade or more on the control of follicular growth and ovulation in mammals. It establishes a single law of maturation for each follicle which describes the interactions between growing follicles. The function put forward is sufficient to explain the constancy of the number of ovulations or large follicles in a female as well as the variability of this number among strains or species and for either induced or spontaneous ovulators. According to the model, the number of ovulations or large follicles lies between two limits that are themselves simple functions of two parameters of the model. Moreover, Lackers model exhibits interesting characteristics in agreement with results obtained by physiologists: in particular, it predicts that the number of ovulating or large follicles is independent of:1.the total number of maturing follicles,2.the process of recruitment of newly maturing follicles towards the terminal maturation (Poisson or other),3.the form of the LH or FSH secretion curves as functions of the systemic level of oestradiol. The model further predicts that4.selection and dominance of follicles result from the feedback between the ovary and the hypophysis through the interactions between follicles; these interactions are expressed by the maturation function of the model.5.recovery from atresia is possible for a follicle: from decreasing, the rate of secretion of oestradiol may increase.6.the revised model suggests a renewal of follicles during the sexual cycle, as “waves of follicular growth”. Lackers model is a model of strict dominance; it maintains a hierarchy of the follicles as soon as they start their final maturation to the ovulations as that is observed in bird or reptile ovary. Such a strict hierarchy is possible but it is probably not a general situation in all mammals. We therefore modified the maturing function of the follicle in order to make it compatible with the observations of physiologists: follicles always interact as in the initial model but they individually become old, the hierarchy of follicles can be modified with time and the largest follicles do not indefinitely grow as in the initial model.

Dynamics and Stability of Induction of the Lactose Operon of Escherischia Coli

The genetical and biochemical mechanisms of the induction process of lactose operon are modeled by a set of nine differential equations, with delayed arguments. A preliminary numerical investigation has shown that the dimension of the system could be reduced to four or even two, so as to allow for an analytical study of stability. When the external concentrations in lactose and glucose are kept fixed, the main results are: (i) There is a unique fixed point; necessary conditions for existence of multiple steady states involve parameters values far beyond any biological meaning. (ii) Parameters values describing known wild and mutant genotypes are within the domain of stability of the unique fixed point, whichever external concentrations may be. (iii) Sets of parameters values involving at least two mutations may be found, for which the stability depends on the external lactose concentration, and such that intracellular concentrations can undergo sustained oscillations; however the periods are quite large and the delays seem to stabilize the system, so that such periodic behaviour has not yet any clear biological meaning.

Algèbres génétiques et mutation quantique

Abstract We apply the ideas of Santilli to develop a theory of quantum mutation for genetic algebras. The case of associative algebras was studied by Osborn, the case of alternative algebras by Myung and for Jordan algebras by Gonzalez. Genetic algebras form a class of algebras different from those described above.