Structural Elucidation and Functional Characterization of the Hyaloperonospora arabidopsidis Effector Protein ATR13

The oomycete Hyaloperonospora arabidopsidis (Hpa) is the causal agent of downy mildew on the model plant Arabidopsis thaliana and has been adapted as a model system to investigate pathogen virulence strategies and plant disease resistance mechanisms. Recognition of Hpa infection occurs when plant resistance proteins (R-genes) detect the presence or activity of pathogen-derived protein effectors delivered to the plant host. This study examines the Hpa effector ATR13 Emco5 and its recognition by RPP13-Nd, the cognate R-gene that triggers programmed cell death (HR) in the presence of recognized ATR13 variants. Herein, we use NMR to solve the backbone structure of ATR13 Emco5, revealing both a helical domain and a disordered internal loop. Additionally, we use site-directed and random mutagenesis to identify several amino acid residues involved in the recognition response conferred by RPP13-Nd. Using our structure as a scaffold, we map these residues to one of two surface-exposed patches of residues under diversifying selection. Exploring possible roles of the disordered region within the ATR13 structure, we perform domain swapping experiments and identify a peptide sequence involved in nucleolar localization. We conclude that ATR13 is a highly dynamic protein with no clear structural homologues that contains two surface-exposed patches of polymorphism, only one of which is involved in RPP13-Nd recognition specificity

Authoring on the Fly

We report about a new way of producing hypermedia documents for supporting teaching at universities. A computer held lecture is automatically converted into the core of a multimedia document and linked together with papers, textbooks, animations and simulations. As an electronic substitute of the blackboard we have used the whiteboard wb of the Mbone toolset and have transmitted the lecture also to remote locations. Our experiments demonstrate that classroom lecturing, distance teaching, and the production of educational hypermedia can be successfully integrated. 1 Computer support for teaching at university level Today personal computers and workstations have spread over offices and laboratories not only in departments for computer science in universities all over the world. Teachers, students and even the administrative personnel have access to a wide variety of computer supported services inclusive access to the Internet. This ubiquitous access to computers has resulted i..