Expression cloning of a fungal proline‐rich glycoprotein specific to the biotrophic interface formed in the Colletotrichum–bean interaction

Abstract

SummaryThe monoclonal antibody, UB25, recognises a glycoprotein specifically located at the biotrophic interface formed in the Colletotrichum lindemuthianum-bean interaction. The antibody labels the walls of intracellular hyphae and the interfacial matrix which separates them from the invaginated host plasma membrane. In Western blots, UB25 recognises a ladder of bands which are multiples of M r 40.5 kDa. A full length cDNA encoding the glycoprotein recognised by UB25 has been isolated by expression cloning and designated CIH1 (Colletotrichum Intracellular Hypha 1). In vitro transcription/translation of CIH1, and transfection of mammalian COS cells, showed that UB25 recognised the expressed product in both procedures confirming that the clones isolated were true positives. Southern analysis of bean and C. lindemuthianum genomic DNA indicated that the CIH1 glycoprotein is fungally encoded and Northern analysis showed that it is only expressed in planta. Analysis of the deduced amino acid sequence of CIH1 indicates the presence of an N-terminal signal sequence and two possible sites for N-glycosylation. The N-terminal domain of the mature protein is rich in proline and contains several short repetitive motifs. CIH1 is thus a fungal proline-rich glycoprotein which appears to form a cross-linked structure in planta and, as such, resembles plant cell wall proline-and hydroxyproline-rich proteins. Possible functions for the CIH1 protein in the establishment and maintenance of biotrophy are discussed.

The molecular mechanisms of conidial germination

“…Monoclonal antibodies against cell wall determinants have been used on expression-clone outer cell wall glycoproteins [16], but their role in conidial germination remains unclear. Biochemical assays, such as protein, RNA, DNA synthesis rates [9,17], and speci¢c activity of enzymes such as trehalose (reviewed in [18]) have also been used.…”

A Parasitic Phase-Specific Adhesin of Coccidioides immitis Contributes to the Virulence of This Respiratory Fungal Pathogen

“…These PRRs frequently occur as multiple tandem repeats and are widely distributed among prokaryotes and eukaryotes (44). Cell-surface expressed fungal and bacterial proteins which contain proline-rich tandem repeats have been suggested to function in adherence to host tissue (33,39). An example is a glycoprotein of Colletotrichum lindemuthianum (CIH1) produced at the surface of intracellular hyphae which infects the tissues of bean plants.…”

“…The N-terminal domain of the mature glycoprotein is rich in proline, contains several short repetitive motifs, and forms cross-links with the plant cell wall. The PRRs of CIH1 appear to be essential for establishment and maintenance of this fungus-host relationship (33). Candida albicans produces a glycoprotein (HWP1) at its hyphal surface that is characterized by tandemly repeated, proline-and glutamine-rich amino acid motifs (39).…”

Differential Expression of Pine and Cronartium quercuum f. sp. fusiforme Genes in Fusiform Rust Galls

“…fusiforme establishes perennial, biotrophic infections on pine, the ability to withstand or circumvent host defenses for extended periods of time is a prerequisite for successful gall induction. A growing body of evidence supports the theory that biotrophic microorganisms enable their symbiotic or parasitic relationships with plants by suppressing host defenses (18,35,45,48,49,63,69,73,86). The rust fungus Uromyces vignae suppresses defenses by decreasing the adhesion between the host plant cell wall and its plasma membrane (57), but in general the mechanisms underlying host defense suppression by biotrophs are not well understood.…”