Rhesus TRIM5α disrupts the HIV-1 capsid at the inter-hexamer interfaces

TRIM proteins play important roles in the innate immune defense against retroviral infection, including human immunodeficiency virus type-1 (HIV-1). Rhesus macaque TRIM5α (TRIM5αrh) targets the HIV-1 capsid and blocks infection at an early post-entry stage, prior to reverse transcription. Studies have shown that binding of TRIM5α to the assembled capsid is essential for restriction and requires the coiled-coil and B30.2/SPRY domains, but the molecular mechanism of restriction is not fully understood. In this study, we investigated, by cryoEM combined with mutagenesis and chemical cross-linking, the direct interactions between HIV-1 capsid protein (CA) assemblies and purified TRIM5αrh containing coiled-coil and SPRY domains (CC-SPRYrh). Concentration-dependent binding of CC-SPRYrh to CA assemblies was observed, while under equivalent conditions the human protein did not bind. Importantly, CC-SPRYrh, but not its human counterpart, disrupted CA tubes in a non-random fashion, releasing fragments of protofilaments consisting of CA hexamers without dissociation into monomers. Furthermore, such structural destruction was prevented by inter-hexamer crosslinking using P207C/T216C mutant CA with disulfide bonds at the CTD-CTD trimer interface of capsid assemblies, but not by intra-hexamer crosslinking via A14C/E45C at the NTD-NTD interface. The same disruption effect by TRIM5αrh on the inter-hexamer interfaces also occurred with purified intact HIV-1 cores. These results provide insights concerning how TRIM5α disrupts the virion core and demonstrate that structural damage of the viral capsid by TRIM5α is likely one of the important components of the mechanism of TRIM5α-mediated HIV-1 restriction. © 2011 Zhao et al

Distribution of introduced and native fish in Patagonia (Argentina): patterns and changes in fish assemblages

The interaction between native fishes and salmonids introduced in Patagonia at the beginning of the 20th Century, developed at the same time as the environmental change. The phenomenon of global warming has led to the formulation of predictions in relation to changes in the distribution of species, in the latitudinal dimension, both at intralacustrine, or small streams levels. The aim of the present work includes three main objectives: a) to compose a general and updated picture of the latitudinal distribution range of native and alien fishes, b) to analyze the historical changes in the relative abundance of Percichthys trucha, Odontesthes sp., and salmonids in lakes and reservoirs, and c) to relate the diversity and relative abundance of native and salmonid fishes to the environmental variables of lakes and reservoirs. We analysed previous records and an ensemble of data about new locations along the northern border of the Patagonian Province. We compared current data about the relative abundance of native fishes and salmonids in lakes and reservoirs, with previous databases (1984–1987). All samplings considered were performed during spring-summer surveys and include relative abundance, as proportions of salmonids, P. trucha, and Odontesthes sp. For the first time, we found changes in fish assemblages from twenty years back up to the present: a significant decline in the relative abundances of salmonids and an increase of P. trucha. We studied the association between the diversity and relative abundance of native and salmonid fishes and the environmental variables of lakes and reservoirs using Canonical Correspondence Analysis. Relative abundance showed mainly geographical cues and the diversity relied largely on morphometric characteristics. Relative abundance and diversity seem to have a common point in the lake area, included into the PAR concept. Native abundance and alien diversity were negatively related with latitude. Greater native diversity was observed in lakes with high PAR compared with salmonids. Historical changes such as southward dispersion, relative abundance changes, and geographical patterns for relative abundance and diversity are basic concepts needed not only in future research but also in management design for Patagonian fish populations.Facultad de Ciencias Naturales y Muse