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| C. Ciências Biológicas - 8. Genética - 2. Genética de Microorganismos | ||
| STRUCTURAL MOTIFS OF PESCADILLO PROTEIN HOMOLOGUES IN Leishmania spp. AS PUTATIVE DETERMINANTS OF VIRULENCE FACTOR | ||
| Elton José Rosas de Vasconcelos 1 (elton@lcc.uece.br), João José de Simoni Gouveia 1, Thiago Dias Ferreira 1, Marianna Collares Albuquerque 1, Allan Rodrigo Soares Maia 1, Daniel Costa Fortier 1, Ana Carolina L. Pacheco 1, Nilo Batista Diniz 1, Michely Correia Diniz 1 e Diana Magalhães de Oliveira 1 | ||
| (1. Núcleo de Genômica e Bioinformática, Fac. de Veterinária, Universidade Estadual do Ceará - UECE) | ||
| INTRODUÇÃO:
As genome, transcriptome and proteome data in pathogens increasingly become available, many important unanswered problems, concerning the pathology they inflict, might benefit from the information that lies on their genome organization. Valuable information can be extracted from analyses of the existence and/or abundance of virulence factors in genomes, whereas the ability of clinicians and pathologists to properly interpret this information will need to rely on more integrated and accessible computational tools. The ongoing analysis of the genome sequences and proteome profiles of Leishmania major and L. infantum, Trypanosoma cruzi, T. brucei and T. gambiensi (accessible at http://www.genedb.org), coupled with our own work on L. chagasi (as part of the Brazilian Northeast Genome Program – http://nugen.lcc.uece.br/progeneProject.htm), prompted us to scrutinize genes and proteins of Leishmania spp., the pathogenic protozoan that causes leishmaniasis, a complex and re-emerging tropical disease. |
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| METODOLOGIA:
It is estimated that 70% of the genes in L. major have no significant similarity to existing genes in sequence databases. Given that the number of experimentally confirmed gene predictions in Leishmania is currently small, we had to extract a large number of consensus sequences for each Leishmania species by examining for putative protein-coding ORFs using a combination of gene prediction tools with semi-automated procedures. Deduced amino acid sequences (from predicted genes) were, then, used as query sequences for local BLASTP searches of the NCBI non-redundant protein database and the GeneDB database. Generally, hits with BLAST scores of >50 and e-values of <1 x 10–6 were considered potentially significant. Each protein sequence was then searched against numerous collections of protein motifs and families, such as UniProt/Swiss-Prot 45.2, ProDom 2004.1, SMART 4.0, Pfam 16.0 and iPfam and PROSITE 18.40. Searches were carried out using various algorithms, usually as web-based tools. BLAST searching of Clusters of Orthologous Groups of Proteins (database COGs) was performed simultaneously, along with identification of putative protein localization sites and transmembrane spanning regions using PSORT and TMHMM version 2.0. Gene ontology (GO) terms were assigned to the predicted proteins, based on their top matches to proteins with GO annotations from SWISSPROT and TREMBL and with AMIGO after geneDB access. |
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| RESULTADOS:
In this study, we present a list of new putative virulence factors in Leishmania spp. that were underscored by our survey and that could be assigned a potential significant role in Leishmania pathogenesis. Among them we identified a few possible pescadillo (PES) homologues in L. major, L. Infantum and L. chagasi, not previously reported or analyzed in this species. The L. major PES homologue has a predicted length of 670 amino acids, containing a zinc-binding region signature and a motif originally identified in the breast and ovarian cancer gene BRCA1. PES protein was originally identified by insertional mutagenesis in zebrafish and it was shown to be essential for embryonic development. It localizes to distinct substructures of the interphase nucleus including nucleoli, the site of ribosome biogenesis. PES is reported to be involved in DNA replication and ribosome biogenesis. We also present an analysis of the predicted PES homologues in Leishmania and provide evidence that it is well conserved among a variety of species, sharing from 32 to 79% sequence homology with yeast, human, zebrafish, plasmodial and trypanosomal PES homologues. |
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| CONCLUSÕES:
All these PES proteins range in size from 582 to 670 amino acids, and each contains several unique structural motifs including a BRCA1 C-terminal (BRCT) domain, two extensive acidic domains in the C terminus, numerous presumptive tyrosine/serine/threonine phosphorylation sites, and several conserved consensus sequences for covalent attachment of SUMO-1 (small ubiquitin modification). All leishmanial PES homologues also contain putative nuclear localization signals. The biochemical function performed by PES has not been defined, but insights into its cellular role can be inferred from examining structural motifs contained within its sequence. The BRCT-domain has more recently been found in several proteins involved in DNA repair, cell cycle control, and/or recombination. Its presence in the leishmanial PES, together with the finding of a BRCA2-like protein in L. donovani (Accession AAQ96330), is provocative and suggests that PES might have important, and unforeseen, functions in the parasite development and infectivity. |
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| Instituição de fomento: FUNCAP, CNPq, FINEP, BNB/FUNDECI | ||
| Trabalho de Iniciação Científica | ||
| Palavras-chave: Leishmania spp.; Pescadillo; Structural Motifs. | ||
| Anais da 57ª Reunião Anual da SBPC - Fortaleza, CE - Julho/2005 |