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Tagging eukaryotic proteins with ubiquitin can target them for proteasomal degradation. However, despite the presence of proteasomes in several bacterial and all archaeal species, prokaryotic homologues of ubiquitin were presumed to be absent. In this Progress article, Heran Darwin describes the characterization of a prokaryotic ubiquitin-like protein (Pup) that is covalently attached to proteins, resulting in their proteasome-mediated degradation.
To evade immune responses in mammalian hosts, many pathogens use complex genetic systems to vary the surface antigens that are recognized by host defences. In this Review, Kirk Deitsch and colleagues highlight how bacterial, protozoan and fungal pathogens from distinct evolutionary lineages have evolved surprisingly similar mechanisms for antigenic variation.
The identification of post-translational histone modifications and chromatin-modifying enzymes in eukaryotic parasites has widened the field of research into epigenetic regulation. Figueiredo, Cross and Janzen compare the role of epigenetics inTrypanosoma bruceiand humans and discuss how studies in such parasites might yield useful information about the evolution of epigenetic processes.
Bacteria from the genusStenotrophomonas are found in a wide range of different environments. Here, Ryan et al. compare the recently sequenced genomes of two different Stenotrophomonasspecies to highlight the possible genetic basis of adaptation to these different niches.
Since 2001, the prevalence and severity ofClostridium difficile infection have increased substantially, and C. difficile is now considered to be one of the most important causes of health care-associated infections. Here, Rupnik, Wilcox and Gerding discuss the recent epidemiological changes in C. difficile infection and our current knowledge of C. difficilevirulence factors.
The evolution and molecular characteristics of theMycobacterium tuberculosiscomplex are hotly debated. Here, Noel Smith and colleagues address several misconceptions about the origins of tuberculosis that have arisen over the years.
