The sulfolobicin genes of Sulfolobus acidocaldarius encode novel antimicrobial proteins.

Crenarchaea, such as Sulfolobus acidocaldarius and Sulfolobus tokodaii, produce antimicrobial proteins called sulfolobicins. These antimicrobial proteins inhibit the growth of closely related species. Here we report the identification of the sulfolobicin-encoding genes in S.

The archaeal cell envelope.

At first glance, archaea and bacteria look alike; however, the composition of the archaeal cell envelope is fundamentally different from the bacterial cell envelope. With just one exception, all archaea characterized to date have only a single membrane and most are covered by a paracrystalline protein layer. This Review discusses our current knowledge of the composition of the archaeal cell surface.

Archaeal flagellar ATPase motor shows ATP-dependent hexameric assembly and activity stimulation by specific lipid binding.

Microbial motility frequently depends on flagella or type IV pili. Using recently developed archaeal genetic tools, archaeal flagella and its assembly machinery have been identified. Archaeal flagella are functionally similar to bacterial flagella and their assembly systems are homologous with type IV pili assembly systems of Gram-negative bacteria.

Archaeal type IV pilus-like structures--evolutionarily conserved prokaryotic surface organelles.

In both bacteria and Archaea, the biosynthesis of type IV pilus-related structures involves a set of core components, including a prepilin peptidase that specifically processes precursors of pilin-like proteins. Although in silico analyses showed that most sequenced archaeal genomes encode predicted pilins and conserved pilus biosynthesis components, recent in vivo analyses of archaeal pili in genetically tractable crenarchaea and euryarchaea revealed Archaea-specific type IV pilus functions and biosynthesis components. Studies in a variety of archaeal species will reveal which type IV pilus-like structures are common in Archaea and which are limited to certain species within this domain.

Ribosome recycling depends on a mechanistic link between the FeS cluster domain and a conformational switch of the twin-ATPase ABCE1.

Despite some appealing similarities of protein synthesis across all phyla of life, the final phase of mRNA translation has yet to be captured. Here, we reveal the ancestral role and mechanistic principles of the newly identified twin-ATPase ABCE1 in ribosome recycling. We demonstrate that the unique iron-sulfur cluster domain and an ATP-dependent conformational switch of ABCE1 are essential both for ribosome binding and recycling.

Simple and elegant design of a virion egress structure in Archaea.

Some viruses of Archaea use an unusual egress mechanism that involves the formation of virus-associated pyramids (VAPs) on the host cell surface. At the end of the infection cycle, these structures open outward and create apertures through which mature virions escape from the cell. Here we describe in detail the structure and composition of VAPs formed by the Sulfolobus islandicus rod-shaped virus 2 (SIRV2) in cells of its hyperthermophilic archaeal host.

Model organisms for genetics in the domain Archaea: methanogens, halophiles, Thermococcales and Sulfolobales.

The tree of life is split into three main branches: eukaryotes, bacteria, and archaea. Our knowledge of eukaryotic and bacteria cell biology has been built on a foundation of studies in model organisms, using the complementary approaches of genetics and biochemistry. Archaea have led to some exciting discoveries in the field of biochemistry, but archaeal genetics has been slow to get off the ground, not least because these organisms inhabit some of the more inhospitable places on earth and are therefore believed to be difficult to culture.

Assembly and function of the archaeal flagellum.

Motility is a common behaviour in prokaryotes. Both bacteria and archaea use flagella for swimming motility, but it has been well documented that structures of the flagellum from these two domains of life are completely different, although they contribute to a similar function. Interestingly, information available to date has revealed that structurally archaeal flagella are more similar to bacterial type IV pili rather than to bacterial flagella.

The bindosome is a structural component of the Sulfolobus solfataricus cell envelope.

Sugar binding proteins of the thermoacidophile Sulfolobus solfataricus function together with ABC transporters in the uptake of sugars. They are synthesized as precursors with a class III signal peptide that are normally found in archaeal flagellins and bacterial type IV pilins. The functional expression of sugar binding proteins at the cell surface is dependent on the bindosome assembly system (Bas) that is homologous to bacterial type IV pilin assembly systems.

Using mindful eating to treat food restriction: a case study.

This case study describes the application of the principles of mindful eating to the treatment of a case of anorexia nervosa. While many clinicians currently use mindful eating in their treatment of binge eating disorder and bulimia, it also may benefit clients who restrict. The client in this case study is a 19-year-old college student with a BMI of 17.

Crenarchaeal biofilm formation under extreme conditions.

Background: Biofilm formation has been studied in much detail for a variety of bacterial species, as it plays a major role in the pathogenicity of bacteria. However, only limited information is available for the development of archaeal communities that are frequently found in many natural environments.

Methodology: We have analyzed biofilm formation in three closely related hyperthermophilic crenarchaeotes: Sulfolobus acidocaldarius, S.

Ligand-induced formation of a transient tryptophan synthase complex with αββ subunit stoichiometry.

The prototypical tryptophan synthases form a stable heterotetrameric αββα complex in which the constituting TrpA and TrpB1 subunits activate each other in a bidirectional manner. The hyperthermophilic archaeon Sulfolobus solfataricus does not contain a TrpB1 protein but instead two members of the phylogenetically distinct family of TrpB2 proteins, which are encoded within (sTrpB2i) and outside (sTrpB2a) the tryptophan operon. It has previously been shown that sTrpB2a does not functionally or structurally interact with sTrpA, whereas sTrpB2i substantially activates sTrpA in a unidirectional manner.

The S-layer glycoprotein of the crenarchaeote Sulfolobus acidocaldarius is glycosylated at multiple sites with chitobiose-linked N-glycans.

Glycosylation of the S-layer of the crenarchaea Sulfolobus acidocaldarius has been investigated using glycoproteomic methodologies. The mature protein is predicted to contain 31 N-glycosylation consensus sites with approximately one third being found in the C-terminal domain spanning residues L(1004)-Q(1395). Since this domain is rich in Lys and Arg and therefore relatively tractable to glycoproteomic analysis, this study has focused on mapping its N-glycosylation.

Identification of a cardiac specific protein transduction domain by in vivo biopanning using a M13 phage peptide display library in mice.

Background: A peptide able to transduce cardiac tissue specifically, delivering cargoes to the heart, would be of significant therapeutic potential for delivery of small molecules, proteins and nucleic acids. In order to identify peptide(s) able to transduce heart tissue, biopanning was performed in cell culture and in vivo with a M13 phage peptide display library.

Methods And Results: A cardiomyoblast cell line, H9C2, was incubated with a M13 phage 12 amino acid peptide display library.

Shaping the archaeal cell envelope.

Although archaea have a similar cellular organization as other prokaryotes, the lipid composition of their membranes and their cell surface is unique. Here we discuss recent developments in our understanding of the archaeal protein secretion mechanisms, the assembly of macromolecular cell surface structures, and the release of S-layer-coated vesicles from the archaeal membrane.

The archaeal exosome localizes to the membrane.

We studied the cellular localization of the archaeal exosome, an RNA-processing protein complex containing orthologs of the eukaryotic proteins Rrp41, Rrp42, Rrp4 and Csl4, and an archaea-specific subunit annotated as DnaG. Fractionation of cell-free extracts of Sulfolobus solfataricus in sucrose density gradients revealed that DnaG and the active-site comprising subunit Rrp41 are enriched together with surface layer proteins in a yellow colored ring, implicating that the exosome is membrane-bound. In accordance with this assumption, DnaG and Rrp41 were detected at the periphery of the cell by immunofluorescence microscopy.

Inducible and constitutive promoters for genetic systems in Sulfolobus acidocaldarius.

Central to genetic work in any organism are the availability of a range of inducible and constitutive promoters. In this work we studied several promoters for use in the hyperthermophilic archaeon Sulfolobus acidocaldarius. The promoters were tested with the aid of an E.

Comparative study of the extracellular proteome of Sulfolobus species reveals limited secretion.

Although a large number of potentially secreted proteins can be predicted on the basis of genomic distribution of signal sequence-bearing proteins, protein secretion in Archaea has barely been studied. A proteomic inventory and comparison of the growth medium proteins in three hyperthermoacidophiles, i.e.

Appendage-mediated surface adherence of Sulfolobus solfataricus.

Attachment of microorganisms to surfaces is a prerequisite for colonization and biofilm formation. The hyperthermophilic crenarchaeote Sulfolobus solfataricus was able to attach to a variety of surfaces, such as glass, mica, pyrite, and carbon-coated gold grids. Deletion mutant analysis showed that for initial attachment the presence of flagella and pili is essential.

"Hot standards" for the thermoacidophilic archaeon Sulfolobus solfataricus.

Within the archaea, the thermoacidophilic crenarchaeote Sulfolobus solfataricus has become an important model organism for physiology and biochemistry, comparative and functional genomics, as well as, more recently also for systems biology approaches. Within the Sulfolobus Systems Biology ("SulfoSYS")-project the effect of changing growth temperatures on a metabolic network is investigated at the systems level by integrating genomic, transcriptomic, proteomic, metabolomic and enzymatic information for production of a silicon cell-model. The network under investigation is the central carbohydrate metabolism.

Acidianus, Sulfolobus and Metallosphaera surface layers: structure, composition and gene expression.

The cell walls of Sulfolobales species consist of proteinaceous S-layers assembled from two polypeptides, SlaA and SlaB. We isolated the large S-layer protein of Acidianus ambivalens and both S-layer subunits of Sulfolobus solfataricus and Metallosphaera sedula, respectively. The slaAB genes, lying adjacently in the chromosomes, are constitutively transcribed as bicistronic operons in A.

Diversity of archaeal type IV pilin-like structures.

Bacterial type IV pili perform important functions in such disparate biological processes as surface adhesion, cell-cell interactions, autoaggregation, conjugation, and twitching motility. Unlike bacteria, archaea use a type IV pilus related structure to drive swimming motility. While this unique flagellum is the best-studied example of an archaeal IV pilus-like structure, recent in silico, in vivo and structural analyses have revealed a highly diverse set of archaeal non-flagellar type IV pilus-like structures.

Ss-LrpB, a transcriptional regulator from Sulfolobus solfataricus, regulates a gene cluster with a pyruvate ferredoxin oxidoreductase-encoding operon and permease genes.

Ss-LrpB is an Lrp-like transcriptional regulator from Sulfolobus solfataricus. Previously, in vitro binding of Ss-LrpB to the control region of its own gene has been extensively studied. However, nothing was known about the physiological role of this regulator yet.

Expanding and understanding the genetic toolbox of the hyperthermophilic genus Sulfolobus.

Although Sulfolobus species are among the best studied archaeal micro-organisms, the development and availability of genetic tools has lagged behind. In the present paper, we discuss the latest progress in understanding recombination events of exogenous DNA into the chromosomes of Sulfolobus solfataricus and Sulfolobus acidocaldarius and their application in the construction of targeted-deletion mutant strains.

SulfoSYS (Sulfolobus Systems Biology): towards a silicon cell model for the central carbohydrate metabolism of the archaeon Sulfolobus solfataricus under temperature variation.

SulfoSYS (Sulfolobus Systems Biology) focuses on the study of the CCM (central carbohydrate metabolism) of Sulfolobus solfataricus and its regulation under temperature variation at the systems level. In Archaea, carbohydrates are metabolized by modifications of the classical pathways known from Bacteria or Eukarya, e.g.