The Experts below are selected from a list of 2046 Experts worldwide ranked by ideXlab platform
Jerry Eichler - One of the best experts on this subject based on the ideXlab platform.
-
Assembling Glycan-Charged Dolichol Phosphates: Chemoenzymatic Synthesis of a Haloferax volcanii N-Glycosylation Pathway Intermediate.
Bioconjugate chemistry, 2017Co-Authors: Yifat Elharar, Ziqiang Guan, Ananda Rao Podilapu, Suvarn S. Kulkarni, Jerry EichlerAbstract:N-glycosylation, the covalent attachment of glycans to select protein target Asn residues, is a post-translational modification performed by all three domains of life. In the halophilic archaea Haloferax volcanii, in which understanding of this universal protein-processing event is relatively well-advanced, genes encoding the components of the archaeal glycosylation (Agl) pathway responsible for the assembly and attachment of an N-linked pentasaccharide have been identified. As elsewhere, the N-linked glycan is assembled on phosphodolichol carriers before transfer to target Asn residues. However, as little is presently known of the Hfx. volcanii Agl pathway at the protein level, the seemingly unique ability of Archaea to use dolichol phosphate (DolP) as the glycan lipid carrier, rather than dolichol pyrophosphate used by eukaryotes, remains poorly understood. With this in mind, a chemoenzymatic approach was taken to biochemically study AglG, one of the five glycosyltransferases of the pathway. Accordingly...
-
Cell Surface Glycosylation Is Required for Efficient Mating of Haloferax volcanii.
Frontiers in microbiology, 2017Co-Authors: Yarden Shalev, Jerry Eichler, Israela Turgeman-grott, Adi Tamir, Uri GophnaAbstract:Halophilic archaea use a fusion-based mating system for lateral gene transfer across cells, yet the molecular mechanisms involved remain unknown. Previous work implied that cell fusion involves cell-cell recognition since fusion occurs more efficiently between cells from the same species. Long believed to be restricted only to Eukarya, it is now known that cells of all three domains of life perform N-glycosylation, the covalent attachment of glycans to select target asparagine residues in proteins, and that this post-translational modification is common for archaeal cell surface proteins. Here, we show that differences in glycosylation of the Haloferax volcanii surface-layer glycoprotein, brought about either by changing medium salinity or by knocking out key glycosylation genes, reduced mating success. Thus, different glycosylation patterns are likely to underlie mating preference in halophilic archaea, contributing to speciation processes.
-
Haloferax volcanii N-glycosylation: delineating the pathway of dTDP-rhamnose biosynthesis.
PloS one, 2014Co-Authors: Lina Kaminski, Jerry EichlerAbstract:In the halophilic archaea Haloferax volcanii, the surface (S)-layer glycoprotein can be modified by two distinct N-linked glycans. The tetrasaccharide attached to S-layer glycoprotein Asn-498 comprises a sulfated hexose, two hexoses and a rhamnose. While Agl11-14 have been implicated in the appearance of the terminal rhamnose subunit, the precise roles of these proteins have yet to be defined. Accordingly, a series of in vitro assays conducted with purified Agl11-Agl14 showed these proteins to catalyze the stepwise conversion of glucose-1-phosphate to dTDP-rhamnose, the final sugar of the tetrasaccharide glycan. Specifically, Agl11 is a glucose-1-phosphate thymidylyltransferase, Agl12 is a dTDP-glucose-4,6-dehydratase and Agl13 is a dTDP-4-dehydro-6-deoxy-glucose-3,5-epimerase, while Agl14 is a dTDP-4-dehydrorhamnose reductase. Archaea thus synthesize nucleotide-activated rhamnose by a pathway similar to that employed by Bacteria and distinct from that used by Eukarya and viruses. Moreover, a bioinformatics screen identified homologues of agl11-14 clustered in other archaeal genomes, often as part of an extended gene cluster also containing aglB, encoding the archaeal oligosaccharyltransferase. This points to rhamnose as being a component of N-linked glycans in Archaea other than Hfx. volcanii.
-
N-glycosylation in Haloferax volcanii: adjusting the sweetness.
Frontiers in microbiology, 2013Co-Authors: Jerry Eichler, Lina Kaminski, Lina Kandiba, Chen Cohen-rosenzweig, Adi Arbiv, Zvia KonradAbstract:Long believed to be restricted to Eukarya, it is now known that cells of all three domains of life perform N-glycosylation, the covalent attachment of glycans to select target protein asparagine residues. Still, it is only in the last decade that pathways of N-glycosylation in Archaea have been delineated. In the haloarchaeon Haloferax volcanii, a series of Agl (archaeal glycosylation) proteins is responsible for the addition of an N-linked pentasaccharide to modified proteins, including the surface (S)-layer glycoprotein, the sole component of the surface layer surrounding the cell. The S-layer glycoprotein N-linked glycosylation profile changes, however, as a function of surrounding salinity. Upon growth at different salt concentrations, the S-layer glycoprotein is either decorated by the N-linked pentasaccharide introduced above or by both this pentasaccharide as well as a tetrasaccharide of distinct composition. Recent efforts have identified Agl5-Agl15 as components of a second Hfx. volcanii N-glycosylation pathway responsible for generating the tetrasaccharide attached to S-layer glycoprotein when growth occurs in 1.75 M but not 3.4 M NaCl-containing medium.
-
lipid modification gives rise to two distinct Haloferax volcanii s layer glycoprotein populations
Biochimica et Biophysica Acta, 2013Co-Authors: Lina Kandiba, Ziqiang Guan, Jerry EichlerAbstract:The S-layer glycoprotein is the sole component of the protein shell surrounding Haloferax volcanii cells. The deduced amino acid sequence of the S-layer glycoprotein predicts the presence of a C-terminal membrane-spanning domain. However, several earlier observations, including the ability of EDTA to selectively solubilize the protein, are inconsistent with the presence of a trans-membrane sequence. In the present report, sequential solubilization of the S-layer glycoprotein by EDTA and then with detergent revealed the existence of two distinct populations of the S-layer glycoprotein. Whereas both S-layer glycoprotein populations underwent signal peptide cleavage and N-glycosylation, base hydrolysis followed by mass spectrometry revealed that a lipid, likely archaetidic acid, modified only the EDTA-solubilized version of the protein. These observations are consistent with the S-layer glycoprotein being initially synthesized as an integral membrane protein and subsequently undergoing a processing event in which the extracellular portion of the protein is separated from the membrane-spanning domain and transferred to a waiting lipid moiety.
María Inés Giménez - One of the best experts on this subject based on the ideXlab platform.
-
Haloferax volcanii proteome response to deletion of a rhomboid protease gene
Journal of Proteome Research, 2018Co-Authors: Mariana Ines Costa, Micaela Cerletti, Christian Trotschel, Rosana E De Castro, Ansgar Poetsch, Rodrigo A. Paggi, María Inés GiménezAbstract:Rhomboids are conserved intramembrane serine proteases involved in cell signaling processes. Their role in prokaryotes is scarcely known and remains to be investigated in Archaea. We previously constructed a rhomboid homologue deletion mutant (ΔrhoII) in Haloferax volcanii, which showed reduced motility, increased novobiocin sensitivity, and an N- glycosylation defect. To address the impact of rhoII deletion on H. volcanii physiology, the proteomes of mutant and parental strains were compared by shotgun proteomics. A total of 1847 proteins were identified (45.8% of H. volcanii predicted proteome), from which 103 differed in amount. Additionally, the mutant strain evidenced 99 proteins with altered electrophoretic migration, which suggested differential post-translational processing/modification. Integral membrane proteins that evidenced variations in concentration, electrophoretic migration, or semitryptic cleavage in the mutant were considered as potential RhoII targets. These included a PrsW protease ho...
-
Archaeal membrane-associated proteases: insights on Haloferax volcanii and other haloarchaea.
Frontiers in microbiology, 2015Co-Authors: María Inés Giménez, Micaela Cerletti, Rosana Esther De CastroAbstract:The function of membrane proteases range from general house-keeping to regulation of cellular processes. Although the biological role of these enzymes in archaea is poorly understood, some of them are implicated in the biogenesis of the archaeal cell envelope and surface structures. The membrane-bound ATP-dependent Lon protease is essential for cell viability and affects membrane carotenoid content in Haloferax volcanii. At least two different proteases are needed in this archaeon to accomplish the posttranslational modifications of the S-layer glycoprotein. The rhomboid protease RhoII is involved in the N-glycosylation of the S-layer protein with a sulfoquinovose-containing oligosaccharide while archaeosortase ArtA mediates the proteolytic processing coupled-lipid modification of this glycoprotein facilitating its attachment to the archaeal cell surface. Interestingly, two different signal peptidase I homologs exist in H. volcanii, Sec11a and Sec11b, which likely play distinct physiological roles. Type IV prepilin peptidase PibD processes flagellin/pilin precursors, being essential for the biogenesis and function of the archaellum and other cell surface structures in H. volcanii.
Julie A. Maupin-furlow - One of the best experts on this subject based on the ideXlab platform.
-
Gene Expression of Haloferax volcanii on Intermediate and Abundant Sources of Fixed Nitrogen.
International journal of molecular sciences, 2019Co-Authors: Sungmin Hwang, Nikita E. Chavarria, Rylee K. Hackley, Amy K. Schmid, Julie A. Maupin-furlowAbstract:Haloferax volcanii, a well-developed model archaeon for genomic, transcriptomic, and proteomic analyses, can grow on a defined medium of abundant and intermediate levels of fixed nitrogen. Here we report a global profiling of gene expression of H. volcanii grown on ammonium as an abundant source of fixed nitrogen compared to l-alanine, the latter of which exemplifies an intermediate source of nitrogen that can be obtained from dead cells in natural habitats. By comparing the two growth conditions, 30 genes were found to be differentially expressed, including 16 genes associated with amino acid metabolism and transport. The gene expression profiles contributed to mapping ammonium and l-alanine usage with respect to transporters and metabolic pathways. In addition, conserved DNA motifs were identified in the putative promoter regions and transcription factors were found to be in synteny with the differentially expressed genes, leading us to propose regulons of transcriptionally co-regulated operons. This study provides insight to how H. volcanii responds to and utilizes intermediate vs. abundant sources of fixed nitrogen for growth, with implications for conserved functions in related halophilic archaea.
-
Chase Assay of Protein Stability in Haloferax volcanii.
Bio-protocol, 2017Co-Authors: Julie A. Maupin-furlowAbstract:Highly regulated and targeted protein degradation plays a fundamental role in almost all cellular processes. Determination of the protein half-life by the chase assay serves as a powerful and popular strategy to compare the protein stability and study proteolysis pathways in cells. Here, we describe a chase assay in Haloferax volcanii, a halophilic archaeon as the model organism.
-
Post-translation modification in Archaea: Lessons from Haloferax volcanii and other haloarchaea
FEMS microbiology reviews, 2012Co-Authors: Jerry Eichler, Julie A. Maupin-furlowAbstract:As an ever-growing number of genome sequences appear, it is becoming increasingly clear that factors other than genome sequence impart complexity to the proteome. Of the various sources of proteomic variability, post-translational modifications (PTMs) most greatly serve to expand the variety of proteins found in the cell. Likewise, modulating the rates at which different proteins are degraded also results in a constantly changing cellular protein profile. While both strategies for generating proteomic diversity are adopted by organisms across evolution, the responsible pathways and enzymes in Archaea are often less well described than are their eukaryotic and bacterial counterparts. Studies on halophilic archaea, in particular Haloferax volcanii, originally isolated from the Dead Sea, are helping to fill the void. In this review, recent developments concerning PTMs and protein degradation in the haloarchaea are discussed.
-
Ubiquitin-like small archaeal modifier proteins (SAMPs) in Haloferax volcanii
Nature, 2010Co-Authors: Matthew A. Humbard, Hugo V. Miranda, Jae-min Lim, David J. Krause, Jonathan R. Pritz, Guangyin Zhou, Sixue Chen, Lance Wells, Julie A. Maupin-furlowAbstract:Archaea, one of three major evolutionary lineages of life, encode proteasomes highly related to those of eukaryotes. In contrast, archaeal ubiquitin-like proteins are less conserved and not known to function in protein conjugation. This has complicated our understanding of the origins of ubiquitination and its connection to proteasomes. Here we report two small archaeal modifier proteins, SAMP1 and SAMP2, with a β-grasp fold and carboxy-terminal diglycine motif similar to ubiquitin, that form protein conjugates in the archaeon Haloferax volcanii. The levels of SAMP-conjugates were altered by nitrogen-limitation and proteasomal gene knockout and spanned various functions including components of the Urm1 pathway. LC-MS/MS-based collision-induced dissociation demonstrated isopeptide bonds between the C-terminal glycine of SAMP2 and the e-amino group of lysines from a number of protein targets and Lys 58 of SAMP2 itself, revealing poly-SAMP chains. The widespread distribution and diversity of pathways modified by SAMPylation suggest that this type of protein conjugation is central to the archaeal lineage. Ubiquitination is an important protein modification process in eukaryotes, but its role in prokaryotes is less certain. Now structural homologues of ubiquitin (small archaeal modifier proteins or SAMPs) are shown to form a large number of protein conjugates in the archaeon Haloferax volcanii. Although Archaea encode proteasomes highly related to those of eukaryotes, archaeal ubiquitin-like proteins are less conserved and not known to function in protein conjugation, complicating our understanding of the origins of ubiquitination. Two small archaeal modifier proteins, SAMP1 and SAMP2, structurally similar to ubiquitin, are now reported to form protein conjugates in the archaeon Haloferax volcanii.
-
Shotgun proteomics of the haloarchaeon Haloferax volcanii.
Journal of proteome research, 2008Co-Authors: P. Aaron Kirkland, Charles J. Daniels, Matthew A. Humbard, Julie A. Maupin-furlowAbstract:Haloferax volcanii, an extreme halophile originally isolated from the Dead Sea, is used worldwide as a model organism for furthering our understanding of archaeal cell physiology. In this study, a combination of approaches was used to identify a total of 1296 proteins, representing 32% of the theoretical proteome of this haloarchaeon. This included separation of (phospho)proteins/peptides by 2-dimensional gel electrophoresis (2-D), immobilized metal affinity chromatography (IMAC), metal oxide affinity chromatography (MOAC), and Multidimensional Protein Identification Technology (MudPIT) including strong cation exchange (SCX) chromatography coupled with reversed phase (RP) HPLC. Proteins were identified by tandem mass spectrometry (MS/MS) using nanoelectrospray ionization hybrid quadrupole time-of-flight (QSTAR XL Hybrid LC/MS/MS System) and quadrupole ion trap (Thermo LCQ Deca). Results indicate that a SCX RP HPLC fractionation coupled with MS/MS provides the best high-throughput workflow for overall prot...
Zvia Konrad - One of the best experts on this subject based on the ideXlab platform.
-
N-glycosylation in Haloferax volcanii: adjusting the sweetness.
Frontiers in microbiology, 2013Co-Authors: Jerry Eichler, Lina Kaminski, Lina Kandiba, Chen Cohen-rosenzweig, Adi Arbiv, Zvia KonradAbstract:Long believed to be restricted to Eukarya, it is now known that cells of all three domains of life perform N-glycosylation, the covalent attachment of glycans to select target protein asparagine residues. Still, it is only in the last decade that pathways of N-glycosylation in Archaea have been delineated. In the haloarchaeon Haloferax volcanii, a series of Agl (archaeal glycosylation) proteins is responsible for the addition of an N-linked pentasaccharide to modified proteins, including the surface (S)-layer glycoprotein, the sole component of the surface layer surrounding the cell. The S-layer glycoprotein N-linked glycosylation profile changes, however, as a function of surrounding salinity. Upon growth at different salt concentrations, the S-layer glycoprotein is either decorated by the N-linked pentasaccharide introduced above or by both this pentasaccharide as well as a tetrasaccharide of distinct composition. Recent efforts have identified Agl5-Agl15 as components of a second Hfx. volcanii N-glycosylation pathway responsible for generating the tetrasaccharide attached to S-layer glycoprotein when growth occurs in 1.75 M but not 3.4 M NaCl-containing medium.
-
Add salt, add sugar: N-glycosylation in Haloferax volcanii.
Biochemical Society transactions, 2013Co-Authors: Lina Kaminski, Shai Naparstek, Zvia Konrad, Lina Kandiba, Chen Cohen-rosenzweig, Adi Arbiv, Jerry EichlerAbstract:Although performed by members of all three domains of life, the archaeal version of N-glycosylation remains the least understood. Studies on Haloferax volcanii have, however, begun to correct this situation. A combination of bioinformatics, molecular biology, biochemical and mass spectrometry approaches have served to delineate the Agl pathway responsible for N-glycosylation of the S-layer glycoprotein, a reporter of this post-translational modification in Hfx. volcanii. More recently, differential N-glycosylation of the S-layer glycoprotein as a function of environmental salinity was demonstrated, showing that this post-translational modification serves an adaptive role in Hfx. volcanii. Furthermore, manipulation of the Agl pathway, together with the capability of Hfx. volcanii to N-glycosylate non-native proteins, forms the basis for establishing this species as a glyco-engineering platform. In the present review, these and other recent findings are addressed.
-
AglR is required for addition of the final mannose residue of the N-linked glycan decorating the Haloferax volcanii S-layer glycoprotein
Biochimica et biophysica acta, 2012Co-Authors: Lina Kaminski, Zvia Konrad, Ziqiang Guan, Mehtap Abu-qarn, Jerry EichlerAbstract:Background Recent studies of Haloferax volcanii have begun to elucidate the steps of N-glycosylation in Archaea, where this universal post-translational modification remains poorly described. In Hfx. volcanii, a series of Agl proteins catalyzes the assembly and attachment of a N-linked pentasaccharide to the S-layer glycoprotein. Although roles have been assigned to the majority of Agl proteins, others await description. In the following, the contribution of AglR to N-glycosylation was addressed.
-
Salty and Sweet: Protein Glycosylation in Haloferax volcanii
2011Co-Authors: Jerry Eichler, Shai Naparstek, Zvia Konrad, Doron Calo, Lina Kaminski, Lina Kandiba, Hilla Magidovich, Sophie Yurist-doutschAbstract:Ever since the discovery of the first glycosylated archaeal protein, namely the Halobacterium salinarum surface-layer glycoprotein some 35 years ago, research on haloarchaea has been at the forefront of efforts to decipher the archaeal version of N-glycosylation, a universal post-translational modification. Now, with the availability of sufficient numbers of genome sequences and the development of appropriate experimental tools, the possibility for detailed molecular analysis of archaeal N-glycosylation pathways is being realized, using haloarchaeal species as model systems. In this chapter, current understanding of N-glycosylation in Archaea and the contribution of studies on Haloferax volcanii to such endeavors are described.
-
Cloning, Expression, and Purification of Functional Sec11a and Sec11b, Type I Signal Peptidases of the Archaeon Haloferax volcanii
Journal of bacteriology, 2006Co-Authors: Amir Fine, Zvia Konrad, Vered Irihimovitch, Idit Dahan, Jerry EichlerAbstract:Across evolution, type I signal peptidases are responsible for the cleavage of secretory signal peptides from proteins following their translocation across membranes. In Archaea, type I signal peptidases combine domainspecific features with traits found in either their eukaryal or bacterial counterparts. Eukaryal and bacterial type I signal peptidases differ in terms of catalytic mechanism, pharmacological profile, and oligomeric status. In this study, genes encoding Sec11a and Sec11b, two type I signal peptidases of the halophilic archaeon Haloferax volcanii, were cloned. Although both genes are expressed in cells grown in rich medium, gene deletion approaches suggest that Sec11b, but not Sec11a, is essential. For purification purposes, tagged versions of the protein products of both genes were expressed in transformed Haloferax volcanii, with Sec11a and Sec11b being fused to a cellulose-binding domain capable of interaction with cellulose in hypersaline surroundings. By employing an in vitro signal peptidase assay designed for use with high salt concentrations such as those encountered by halophilic archaea such as Haloferax volcanii, the signal peptide-cleaving activities of both isolated membranes and purified Sec11a and Sec11b were addressed. The results show that the two enzymes differentially cleave the assay substrate, raising the possibility that the Sec11a and Sec11b serve distinct physiological functions.
Micaela Cerletti - One of the best experts on this subject based on the ideXlab platform.
-
Haloferax volcanii proteome response to deletion of a rhomboid protease gene
Journal of Proteome Research, 2018Co-Authors: Mariana Ines Costa, Micaela Cerletti, Christian Trotschel, Rosana E De Castro, Ansgar Poetsch, Rodrigo A. Paggi, María Inés GiménezAbstract:Rhomboids are conserved intramembrane serine proteases involved in cell signaling processes. Their role in prokaryotes is scarcely known and remains to be investigated in Archaea. We previously constructed a rhomboid homologue deletion mutant (ΔrhoII) in Haloferax volcanii, which showed reduced motility, increased novobiocin sensitivity, and an N- glycosylation defect. To address the impact of rhoII deletion on H. volcanii physiology, the proteomes of mutant and parental strains were compared by shotgun proteomics. A total of 1847 proteins were identified (45.8% of H. volcanii predicted proteome), from which 103 differed in amount. Additionally, the mutant strain evidenced 99 proteins with altered electrophoretic migration, which suggested differential post-translational processing/modification. Integral membrane proteins that evidenced variations in concentration, electrophoretic migration, or semitryptic cleavage in the mutant were considered as potential RhoII targets. These included a PrsW protease ho...
-
Haloferax volcanii Proteome Response to Deletion of a Rhomboid Protease Gene
2018Co-Authors: Mariana I. Costa, Micaela Cerletti, Rosana E De Castro, Ansgar Poetsch, Roberto A. Paggi, Christian Trötschel, María I. GiménezAbstract:Rhomboids are conserved intramembrane serine proteases involved in cell signaling processes. Their role in prokaryotes is scarcely known and remains to be investigated in Archaea. We previously constructed a rhomboid homologue deletion mutant (ΔrhoII) in Haloferax volcanii, which showed reduced motility, increased novobiocin sensitivity, and an N- glycosylation defect. To address the impact of rhoII deletion on H. volcanii physiology, the proteomes of mutant and parental strains were compared by shotgun proteomics. A total of 1847 proteins were identified (45.8% of H. volcanii predicted proteome), from which 103 differed in amount. Additionally, the mutant strain evidenced 99 proteins with altered electrophoretic migration, which suggested differential post-translational processing/modification. Integral membrane proteins that evidenced variations in concentration, electrophoretic migration, or semitryptic cleavage in the mutant were considered as potential RhoII targets. These included a PrsW protease homologue (which was less stable in the mutant strain), a predicted halocyanin, and six integral membrane proteins potentially related to the mutant glycosylation (S-layer glycoprotein, Agl15) and cell adhesion/motility (flagellin1, HVO_1153, PilA1, and PibD) defects. This study investigated for the first time the impact of a rhomboid protease on the whole proteome of an organism
-
Data in support of global role of the membrane protease LonB in Archaea: Potential protease targets revealed by quantitative proteome analysis of a lonB mutant in Haloferax volcanii
Data in brief, 2015Co-Authors: Micaela Cerletti, Ansgar Poetsch, Roberto A. Paggi, Carina Ramallo Guevara, Rosana Esther De CastroAbstract:This data article provides information in support of the research article “Global role of the membrane protease LonB in Archaea: Potential protease targets revealed by quantitative proteome analysis of a lonB mutant in Haloferax volcanii” [1]. The proteome composition of a wt and a LonB protease mutant strain (suboptimal expression) in the archaeon Haloferax volcanii was assessed by a quantitative shotgun proteomic approach. Membrane and cytosol fractions of H. volcanii strains were examined at two different growth stages (exponential and stationary phase). Data is supplied in the present article. This study represents the first proteome examination of a Lon-deficient cell of the Archaea Domain.
-
Archaeal membrane-associated proteases: insights on Haloferax volcanii and other haloarchaea.
Frontiers in microbiology, 2015Co-Authors: María Inés Giménez, Micaela Cerletti, Rosana Esther De CastroAbstract:The function of membrane proteases range from general house-keeping to regulation of cellular processes. Although the biological role of these enzymes in archaea is poorly understood, some of them are implicated in the biogenesis of the archaeal cell envelope and surface structures. The membrane-bound ATP-dependent Lon protease is essential for cell viability and affects membrane carotenoid content in Haloferax volcanii. At least two different proteases are needed in this archaeon to accomplish the posttranslational modifications of the S-layer glycoprotein. The rhomboid protease RhoII is involved in the N-glycosylation of the S-layer protein with a sulfoquinovose-containing oligosaccharide while archaeosortase ArtA mediates the proteolytic processing coupled-lipid modification of this glycoprotein facilitating its attachment to the archaeal cell surface. Interestingly, two different signal peptidase I homologs exist in H. volcanii, Sec11a and Sec11b, which likely play distinct physiological roles. Type IV prepilin peptidase PibD processes flagellin/pilin precursors, being essential for the biogenesis and function of the archaellum and other cell surface structures in H. volcanii.
