57º Congresso Brasileiro de Genética Resumos do 57º Congresso Brasileiro de Genética • 30 de agosto a 2 de setembro de 2011 Centro de Convenções do Hotel Monte Real Resort • Águas de Lindóia • SP • Brasil www.sbg.org.br - ISBN 978-85-89109-06-2 192 Molecular characterization of a pathogenesisrelated protein 4, PnPR4, from black pepper (Piper nigrum L.) Tavares, LSC; Lima, AM; Ferreira, WAS; Brito, WU; Reis, SP; Pessoa, EC and de Souza*, CRB. Laboratório de Biologia Molecular, Instituto de Ciências Biológicas, Universidade Federal do Pará, Guamá, Belém-PA, Brasil, CEP: 66075-110. *E-mail: [email protected] Keywords: Bioinformatics analysis, Black pepper, Molecular characterization, PnPR4 protein, Plant-pathogen interaction Pathogenesis-related protein 4 (PR-4) is considered a potent antifungal due to its property of chitinase, catalyzing the hydrolysis of chitin present in the cell wall of fungi. Several studies have showed that PR-4 proteins exhibit potent and broad-spectrum antifungal activity against many agronomically important pathogenic fungi. A recent study reported by our group identiﬁed a full-length cDNA sequence coding for a PR-4 protein of black pepper, named PnPR4, expressed during interaction with Fusarium solani f. sp. piperis. Therefore, the aim of this work was to characterize the PnPR4 deduced amino acid sequence by Bioinformatics analyses. Our results showed that PnPR4 protein comprises a 141 amino acid polypeptide with a calculated molecular weight of 15.6 kDa and isoelectric point of 8.71. Blast analysis showed that this protein exhibits a high identity with PR4 protein from Brassica rapa subsp. Pekinensis (AAN23106). The hydropathy proﬁle of the PnPR4 using Kyte-Doolittle algorithm revealed a highly hydrophobic N-terminal region and some hydrophilic regions toward the carboxyl terminus. Furthermore, secondary structure prediction analysis using the PSIPRED Protein structure Prediction Server revealed that PnPR4 is composed of three �-helices and six �-strands. In addition, PnPR4 showed a signal peptide predicted at its N-terminus, which corresponds to the highly hydrophobic region, and lacks the C-terminal extension involved in vacuolar targeting, indicating that this protein has an extracellular localization. A main C-terminal domain comprising amino acids 22–141 was found in PnPR4, indicating that it belongs to the Barwin family. The PnPR4 protein does not contain a chitin-binding domain, suggesting that this protein belongs to class II of the PR4 family. These results are corroborated by phylogenetic tree, where PnPR4 clustered together with class II PR4 from dicot species. Financial support: FAPESPA/Sedect-PA, CNPq, CAPES and UFPA.