Molecular analysis of aminopeptidase pumAPE from Ustilago maydis encoded by APEum gene: enzyme purification and differential expression

Date

2006

Authors

Miramón Martínez, P.
Noriega Reyes, M.Y.
Mercado Flores, Y.
Ramírez Zavala, B.
Hernández Rodríguez, C.
Villa Tanaca, L.

Director

Publisher

Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Acceso abierto / Sarbide irekia
Contribución a congreso / Biltzarrerako ekarpena
Versión publicada / Argitaratu den bertsioa

Project identifier

Abstract

Heterobasidiomycete Ustilago maydis is a dimorphic phytopathogenic fungus, causal agent of corn smut, a widespread disease. Recently, proteolytic system of this fungus was described and an aminopeptidase activity, probably involved in pathogenicity, was detected. The aminopeptidase pumAPE was purified from the haploid phase of U. maydis FB1 strain. The purification procedure consisted of ammonium sulphate fractionation and three chromatographic steps, resulting in a 23% recovery. The molecular mass of the dimeric enzyme was estimated to be 110 kDa and 58 kDa by gel filtration chromatography and SDS-PAGE respectively. Enzymatic activity was optimal at pH 7.0 and 35 ºC toward Lys-pNA and the pI was determined to be 5.1. The enzyme was inhibited by EDTA-Na2, 1,10-phenanthroline, bestantin, PMSF and several divalent cations (Cu2+, Hg2+ and Zn2+). The aminopeptidase exhibited a higher specificity for substrates with lysine and arginine in the N-position. The Km value was 54.4 μM and the Vmax value was 408 μmol min-1 mg-1 for Lys-pNA. A pair of primers was designed in order to amplify the gene APEum encoding this activity. In order to determine the number of copies in the genome, a APEum gene fragment was used as probe in a Southern blot. Only one copy of the gene by genome was detected. Also, differential expression of APEum was assessed under different physiological conditions. In brief, high expression levels were detected on media supplemented with corn infusion, proline, and ammonium.

Description

Resumen del poster presentado al VI Meeting on Genetics and Cellular Biology of Basidiomycetes (GCBB-VI), organizado por y celebrado en la Universidad Pública de Navarra el 3-6 de junio de 2005.

Keywords

Ustilago maydis, pumAPE, APEum gene

Department

Faculty/School

Degree

Doctorate program

item.page.cita

item.page.rights

© Autores; Universidad Pública de Navarra. Esta publicación no puede ser reproducida, almacenada o transmitida total o parcialmente, sea cual fuere el medio y el procedimiento, incluidas las fotocopias, sin permiso previo concedido por escrito por los titulares del copyright.

Los documentos de Academica-e están protegidos por derechos de autor con todos los derechos reservados, a no ser que se indique lo contrario.