title: The rust transferred proteins-a new family of effector proteins exhibiting protease inhibitor function.
abstract: Only few fungal effectors have been described to be delivered into the host cell during obligate biotrophic interactions. RTP1p, from the rust fungi Uromyces fabae and U. striatus, was the first fungal protein for which localization within the host cytoplasm could be demonstrated directly. We investigated the occurrence of RTP1 homologues in rust fungi and examined the structural and biochemical characteristics of the corresponding gene products. The analysis of 28 homologues showed that members of the RTP family are most likely to occur ubiquitously in rust fungi and to be specific to the order Pucciniales. Sequence analyses indicated that the structure of the RTPp effectors is bipartite, consisting of a variable N-terminus and a conserved and structured C-terminus. The characterization of Uf-RTP1p mutants showed that four conserved cysteine residues sustain structural stability. Furthermore, the C-terminal domain exhibits similarities to that of cysteine protease inhibitors, and it was shown that Uf-RTP1p and Us-RTP1p are able to inhibit proteolytic activity in Pichia pastoris culture supernatants. We conclude that the RTP1p homologues constitute a rust fungi-specific family of modular effector proteins comprising an unstructured N-terminal domain and a structured C-terminal domain, which exhibit protease inhibitory activity possibly associated with effector function during biotrophic interactions.
authors.affiliation: Phytopathologie, Fachbereich Biologie, Universität Konstanz, 78457, Konstanz, Germany.
authors.forename: Klara
authors.initials: K
authors.lastname: Pretsch
authors.forename: Ariane
authors.initials: A
authors.lastname: Kemen
authors.forename: Eric
authors.initials: E
authors.lastname: Kemen
authors.forename: Matthias
authors.initials: M
authors.lastname: Geiger
authors.forename: Kurt
authors.initials: K
authors.lastname: Mendgen
authors.forename: Ralf
authors.initials: R
authors.lastname: Voegele
mesh_terms: D000595:Amino Acid Sequence; D001487:Basidiomycota / Q000187:drug effects / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000737:chemistry / Q000494:pharmacology; D004220:Disulfides / Q000378:metabolism; D005091:Exons / Q000235:genetics; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D007438:Introns / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D010843:Pichia / Q000187:drug effects / Q000378:metabolism; D011480:Protease Inhibitors / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D055550:Protein Stability / Q000187:drug effects; D017434:Protein Structure, Tertiary; D059748:Proteolysis / Q000187:drug effects; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D015853:Cysteine Proteinase Inhibitors; D004220:Disulfides; D005656:Fungal Proteins; D011480:Protease Inhibitors