The hyperthermophilic peptide-fermenting sulfur archaebacterium Hyperthermus butylicus was isolated from the sea floor of a solfataric habitat with temperatures of up to 112°C on the coast of the island of Sao Miguel, Azores. The organism grows at up to 108°C, grows optimally between 95 and 106°C at 17 g of NaCl per liter and pH 7.0, utilizes peptide mixtures as carbon and energy sources, and forms H2S from elemental sulfur and molecular hydrogen as a growth-stimulating accessory energy source but not by sulfur respiration. The same fermentation products, C02, 1-butanol, acetic acid, phenylacetic acid, and a trace of hydroxyphenylacetic acid, are formed both with and without of So and H2. Its ether lipids, the absence of a mureine sacculus, the nature of the DNA-dependent RNA polymerase, and phylogenetic classification by DNA-rRNA cross-hybridization characterize H. butylicus as part of a novel genus of the major branch of archaebacteria comprising the orders Thermoproteales and Sulfolobales, representing a particularly long lineage bifurcating with the order Sulfolobales above the branching off of the genus Thermoproteus and distinct from the genera Desulfurococcus and Pyrodictium.Extremely thermophilic sulfur-reducing archaebacteria (13, 14) thrive either chemolithoautotrophically, utilizing CO2 as the sole carbon source and synthesis of H2S from SO and molecular hydrogen as the energy source, or by sulfur respiration of various organic carbon and energy sources.

A comprehensive, quantified identification of the mRNA-binding and whole cell proteomes in the three main Leishmania lifecycle stages, the first such comparison in kinetoplastid parasites, demonstrates trans -regulator RBPs select distinct, specific mRNA target pools in a stage-regulated manner despite equivalent, constitutive transcript levels available. Results further indicate that in L. mexicana parasites, mRNA levels are not a strong predictor of whole cell expression or RNA binding potential of encoded proteins. Included are the first proteomes from the human-infective metacyclic promastigote stage.

Highlights d In vitro generation of hybrids using cultured promastigotes of Leishmania tropica d Whole-genome sequencing indicates that the progeny clones are full genomic hybrids d In vitro hybridization can be used to generate large numbers of recombinant parasites

SummaryProtein arginine methylation is a widely conserved post-translational modification performed by arginine methyltransferases (PRMTs). However, its functional role in parasitic protozoa is still under-explored. The Leishmania major genome encodes five PRMT homologs, including PRMT7. Here we show that LmjPRMT7 expression and arginine monomethylation are tightly regulated in a lifecycle stage-dependent manner. LmjPRMT7 levels are higher during the early promastigote logarithmic phase, negligible at stationary and late-stationary phases and rise once more post-differentiation to intracellular amastigotes. Immunofluorescence and co-immunoprecipitation studies demonstrate that LmjPRMT7 is a cytosolic protein associated with several RNA-binding proteins (RBPs) from which Alba20 is monomethylated only in LmjPRMT7-expressing promastigote stages. In addition, Alba20 protein levels are significantly altered in stationary promastigotes of the LmjPRMT7 knockout mutant. Considering RBPs are well-known mammalian PRMT substrates, our data suggest that arginine methylation via LmjPRMT7 may modulate RBP function during Leishmania spp. lifecycle progression. Importantly, genomic deletion of the LmjPRMT7 gene leads to an increase in parasite infectivity both in vitro and in vivo, while lesion progression is significantly reduced in LmjPRMT7-overexpressing parasites. This study is the first to describe a role of Leishmania protein arginine methylation in host-parasite interactions.