Biomedical subjects

Luisa Castagnoli

Publications and source records attributed to Luisa Castagnoli.

8 recordsLinked to original sources

PubMed2006

MINT: the Molecular INTeraction database.

The Molecular INTeraction database (MINT, http://mint.bio.uniroma2.it/mint/) aims at storing, in a structured format, information about molecular interactions (MIs) by extracting experimental details from work published in peer-reviewed journals. At present the MINT team focuses the curation work on physical interactions between proteins. Genetic or computationally inferred interactions are not included in the database. Over the past four years MINT has undergone extensive revision. The new version of MINT is based on a completely remodeled database structure, which offers more efficient data exploration and analysis, and is characterized by entries with a richer annotation. Over the past few years the number of curated physical interactions has soared to over 95 000. The whole dataset can be freely accessed online in both interactive and batch modes through web-based interfaces and an FTP server. MINT now includes, as an integrated addition, HomoMINT, a database of interactions between human proteins inferred from experiments with ortholog proteins in model organisms (http://mint.bio.uniroma2.it/mint/).

Animals↗

PubMed2006

DOMINO: a database of domain-peptide interactions.

Many protein interactions are mediated by small protein modules binding to short linear peptides. DOMINO (http://mint.bio.uniroma2.it/domino/) is an open-access database comprising more than 3900 annotated experiments describing interactions mediated by protein-interaction domains. DOMINO can be searched with a versatile search tool and the interaction networks can be visualized with a convenient graphic display applet that explicitly identifies the domains/sites involved in the interactions.

Binding Sites↗

PubMed2005

Methods to reveal domain networks.

The development and application of high-throughput technology to study protein interactions has led to the construction of complex interaction maps, the correct interpretation of which is crucial to the identification of targets for drug development. Here we propose that a more informative description of protein interaction networks can be achieved by considering explicitly the modular nature of proteins. In this representation, proteins are drawn as covalently linked modular domains binding to their target sites in partner proteins. Families of conserved modules that bind to relatively short peptides mediate a large fraction of the non-covalent interactions linking different proteins in the network. As these interactions are often involved in the propagation of signal transduction, determining the recognition specificity of each domain family member is an essential step toward a functional description of the global interactome.

Peptide Library↗

PubMed2004

Selectivity and promiscuity in the interaction network mediated by protein recognition modules.

A substantial fraction of protein interactions in the cell is mediated by families of protein modules binding to relatively short linear peptides. Many of these interactions have a high dissociation constant and are therefore suitable for supporting the formation of dynamic complexes that are assembled and disassembled during signal transduction. Extensive work in the past decade has shown that, although member domains within a family have some degree of intrinsic peptide recognition specificity, the derived interaction networks display substantial promiscuity. We review here recent advances in the methods for deriving the portion of the protein network mediated by these domain families and discuss how specific biological outputs could emerge in vivo despite the observed promiscuity in peptide recognition in vitro.

Animals↗

PubMed2004

Protein interaction networks by proteome peptide scanning.

A substantial proportion of protein interactions relies on small domains binding to short peptides in the partner proteins. Many of these interactions are relatively low affinity and transient, and they impact on signal transduction. However, neither the number of potential interactions mediated by each domain nor the degree of promiscuity at a whole proteome level has been investigated. We have used a combination of phage display and SPOT synthesis to discover all the peptides in the yeast proteome that have the potential to bind to eight SH3 domains. We first identified the peptides that match a relaxed consensus, as deduced from peptides selected by phage display experiments. Next, we synthesized all the matching peptides at high density on a cellulose membrane, and we probed them directly with the SH3 domains. The domains that we have studied were grouped by this approach into five classes with partially overlapping specificity. Within the classes, however, the domains display a high promiscuity and bind to a large number of common targets with comparable affinity. We estimate that the yeast proteome contains as few as six peptides that bind to the Abp1 SH3 domain with a dissociation constant lower than 100 microM, while it contains as many as 50-80 peptides with corresponding affinity for the SH3 domain of Yfr024c. All the targets of the Abp1 SH3 domain, identified by this approach, bind to the native protein in vivo, as shown by coimmunoprecipitation experiments. Finally, we demonstrate that this strategy can be extended to the analysis of the entire human proteome. We have developed an approach, named WISE (whole interactome scanning experiment), that permits rapid and reliable identification of the partners of any peptide recognition module by peptide scanning of a proteome. Since the SPOT synthesis approach is semiquantitative and provides an approximation of the dissociation constants of the several thousands of interactions that are simultaneously analyzed in an array format, the likelihood of each interaction occurring in any given physiological settings can be evaluated. WISE can be easily extended to a variety of protein interaction domains, including those binding to modified peptides, thereby offering a powerful proteomic tool to help completing a full description of the cell interactome.

Animals↗

PubMed2002

Can we infer peptide recognition specificity mediated by SH3 domains?

Protein interaction domain families that modulate the formation of macromolecular complexes recognize specific sequence or structural motifs. For instance SH3 and WW domains bind to polyproline peptides while SH2 and FHA domains bind to peptides phosphorylated in Tyr and Thr respectively. Within each family, variations in the chemical characteristics of the domain binding pocket modulate a finer peptide recognition specificity and, as a consequence, determine the selection of functional protein partners in vivo. In the proteomic era there is the need for reliable inference methods to help restricting the sequence space of the putative targets to be confirmed experimentally by more laborious experimental approaches. Here we will review the published data about the peptide recognition specificity of the SH3 domain family and we will propose a classification of SH3 domains into eight classes. Finally, we will discuss whether the available information is sufficient to infer the recognition specificity of any uncharacterized SH3 domain.

Amino Acid Sequence↗

PubMed2001

A combined experimental and computational strategy to define protein interaction networks for peptide recognition modules.

Peptide recognition modules mediate many protein-protein interactions critical for the assembly of macromolecular complexes. Complete genome sequences have revealed thousands of these domains, requiring improved methods for identifying their physiologically relevant binding partners. We have developed a strategy combining computational prediction of interactions from phage-display ligand consensus sequences with large-scale two-hybrid physical interaction tests. Application to yeast SH3 domains generated a phage-display network containing 394 interactions among 206 proteins and a two-hybrid network containing 233 interactions among 145 proteins. Graph theoretic analysis identified 59 highly likely interactions common to both networks. Las17 (Bee1), a member of the Wiskott-Aldrich Syndrome protein (WASP) family of actin-assembly proteins, showed multiple SH3 interactions, many of which were confirmed in vivo by coimmunoprecipitation.

Algorithms↗

PubMed2001

Unusual binding properties of the SH3 domain of the yeast actin-binding protein Abp1: structural and functional analysis.

Abp1p is an actin-binding protein that plays a central role in the organization of Saccharomyces cerevisiae actin cytoskeleton. By a combination of two-hybrid and phage-display approaches, we have identified six new ligands of the Abp1-SH3 domain. None of these SH3-mediated novel interactions was detected in recent all genome high throughput protein interaction projects. Here we show that the SH3-mediated association of Abp1p with the Ser/Thr kinases Prk1p and Ark1p is essential for their localization to actin cortical patches. The Abp1-SH3 domain has a rather unusual binding specificity, because its target peptides contain the tetrapentapeptide +XXXPXXPX+PXXL with positive charges flanking the polyproline core on both sides. Here we present the structure of the Abp1-SH3 domain solved at 1.3-A resolution. The peptide-binding pockets in the SH3 domain are flanked by two acidic residues that are uncommon at those positions in the SH3 domain family. We have shown by site-directed mutagenesis that one of these negatively charged side chains may be the key determinant for the preference for non-classical ligands.

Actins↗