A novel ?-glucosidase in Uromyces fabae: feast or fight?

Abstract

A novel b-glucosidase in Uromyces fabae : feast or fight?Abstract Efficient nutrient mobilization is a key element for biotrophic plant parasites such as the rust fungi. In the course of a cDNA library screen for elements involved in sugar utilization in Uromyces fabae, we identified a sequence with homology to b-glucosidases. Full-length genomic and cDNA clones of the gene, termed BGL1, were isolated and sequenced. The BGL1 gene comprises 3,372 nucleotides, including nine introns. The open reading frame encompasses 2,532 bases and codes for a polypeptide of 843 amino acids with an apparent molecular mass of 92.4 kDa. Analysis of the polypeptide revealed a potential secretion signal, indicating an extracellular localization of mature BGL1p (89.8 kDa). BGL1 seems to be expressed in all stages of growth, including haustoria, the feeding structures of rust fungi. In the course of immunolocalization studies, the gene product BGL1p was localized in the periphery of intercellular hyphae and haustoria. On the basis of sequence homology, the BGL1 gene was identified as a fungal b-glucosidase.

Nutrient uptake in rust fungi: how sweet is parasitic life?

“…However, BGL1 shows a different expression pattern than HXT1. Therefore, there might be alternative or additional roles for this enzyme (Haerter and Voegele 2004).…”

“…In fungi and bacteria, for example, ß-glucosidases are involved in cellulose and cellobiose catabolism as part of the cellulase complex and thus play a role in the process of biomass conversion (Leah et al 1995). BGL1p has the capacity to use cellobiose, a breakdown product of cellulose, as a substrate, and consequently could make degradation products of the plant cell wall available for fungal nutrition (Haerter and Voegele 2004). However, BGL1 shows a different expression pattern than HXT1.…”

“…Another source at least for the HXT1p substrate D-glucose could be BGL1p, a ß-glucosidase (ß-D-glucoside glucohydrolase [EC 3.2.1.21]) (Haerter and Voegele 2004). ß-glucosidases are a subgroup of O-glycosyl hydrolases, and occur widely in prokaryotes and eukaryotes (Bhatia et al 2002).…”

Cloning and Characterization of a Novel Invertase from the Obligate Biotroph Uromyces fabae and Analysis of Expression Patterns of Host and Pathogen Invertases in the Course of Infection

“…Proteins used for immunoblot analysis were obtained according to Haerter and Voegele (2004) with the following modifications. Protein was precipitated from 48-h-old S. cerevisiae SEY2102 pDR195::INV1 cultures by treatment of the cells with 40% TCA.…”

The Uredinales: Cytology, Biochemistry, and Molecular Biology

“…The protein shows high homology to other fungal β-glucosidases involved in the detoxification of saponins (Haerter and Voegele 2004). It is therefore possible that BGL1p has additional or alternative functions other than providing substrate for HXT1p.…”