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Retroviruses, which encode fewer than ten genes, need to interact with cellular proteins for virtually all aspects of their replication cycle. In this Review, Stephen Goff describes how host factors and cellular pathways are exploited at each stage of the retrovirus lifecycle. Throughout, comparisons are drawn between HIV and other retroviruses.
Peptidoglycan recognition proteins (PGRPs) are innate immune receptors that are highly conserved from insects to mammals. Recent studies have revealed that, despite this conservation, insect and mammalian PGRPs defend host cells against infection by different mechanisms. Julien Royet and Roman Dziarski review these contrasting modes of action.
RNase Z is the endoribonuclease responsible for the maturation of the 3′-end of transfer RNAs. Here, Condon and colleagues outline the recent important developments that have contributed to our understanding of this enzyme in prokaryotes.
Rather than using a conventional type I or II fatty-acid synthase,Trypanosoma bruceisynthesize most of their fatty acids by an unprecedented mechanism. Here, Paul Englund and colleagues describe this unusual metabolic system and how it contributes to the unique biology of these parasites.
Pneumonia caused by the fungusPneumocystisis the most prevalent opportunistic infection in patients with AIDS. Here, Charles Thomas and Andrew Limper review the latest knowledge on the biology and pathogenesis of this opportunistic fungal pathogen.
Focusing on theUstilago maydismodel system, Gero Steinberg discusses recent advances in our understanding of endosome motility in fungal hyphae, speculating on possible roles of endosome motility in cell polarization and retrograde signalling to the nucleus.
The environmental distribution of the Archaea is distinct from that of the Bacteria, but no single principle provides a satisfactory explanation for their ecological differences. David Valentine proposes a hypothesis to account for the success of the Archaea. He examines archaeal metabolism with respect to ecology and argues that the Archaea are better adapted than the Bacteria to chronic energy stress.
