Classification of AAA+ proteins

AAA+ proteins form a large superfamily of P-loop ATPases involved in the energy-dependent unfolding and disaggregation of macromolecules. In a clustering study aimed at defining the AAA proteins within this superfamily, we generated a map of AAA+ proteins based on sequence similarity, which suggested higher-order groups. A classification based primarily on morphological characteristics, which was proposed at the same time, differed from the cluster map in several aspects, such as the position of RuvB-like helicases and the inclusion of divergent clades, such as viral SF3 helicases and plant disease resistance proteins (RFL1). Here, we establish the presence of an alpha-helical domain C-terminal to the ATPase domain (the C-domain) as characteristic for AAA+ proteins and re-evaluate all clades proposed to belong to this superfamily, based on this characteristic. We find that RFL1 and its homologs (APAF-1, CED-4, MalT, and AfsR) are AAA+ proteins and SF3 helicases are not. We also present a new and more comprehensive cluster map, which assigns a central position to RuvB and clarifies the relationships between the clades of the AAA+ superfamily

The ‘Complex World’ of the Hsp90 Co-chaperone R2TP

The Hsp90 co-chaperone R2TP consists of the AAA+ ATPases, RUVBL1 (Rvb1p in yeast) and RUVBL2 (Rvb2 in yeast), which together make up a heterohexameric ring, in complex with PIH1D1 (Pih1p in yeast) and RPAP3 (Tah1p in yeast). R2TP is involved in the activation of client proteins, such as phosphatidylinositol 3 kinase-related kinases, including mTORC1, ATM, DNA-PK, SMG and ATR/ATRIP, or in the assembly of protein complexes including those of RNA polymerase and snoRNPs, amongst others. In other cases, the role of the TP component (RPAP3-PIH1D1) of R2TP, and consequently Hsp90, is controversial. None-the-less, the extensive role of RUVBL1-RUVBL2 complex in cells, either with or without Hsp90, means that dysfunction of these AAA+ ATPases, Hsp90 or components of the complexes they assemble leads to diseases such as cancer, ciliary dyskinesia and in the case of defects in ATM to ataxia telangiectasia-like syndrome. Recent advances in determining the structure of the R2TP complex has led to an increased understanding of the assembly and function of the R2TP complex. In this review we discuss the current structural advances in determining the architecture of the R2TP complex and the advances made in understanding its active state

Confucius Institutes and the rise of China

Abstract: Since 2004 China has set up over 700 Confucius Institutes and Confucius Classrooms around the world to promote its language and culture and thereby to shape its image. Despite this impressive number Confucius Institutes are surprisingly understudied, especially in terms of their actual structure, operation mode and activities. This paper uses German Confucius Institutes as a case study to bridge this gap. It first discusses the concepts of public and cultural diplomacy and culture institutes as a conceptual tool to analyze Confucius Institutes. It then turns to the case study to provide empirical data to better understand this instrument of China’s image shaping efforts. It argues that Confucius Institutes are connected to the rise of China and a unique member of the family of national culture institutes