Genome Sequence of the Polysaccharide-Degrading, Thermophilic Anaerobe
            <i>Spirochaeta thermophila</i>
            DSM 6192

Angelov, Angel; Liebl, S.; Ballschmiter, Meike; Bömeke, Mechthild; Lehmann, Rüdiger; Liesegang, Heiko; Daniel, Rolf; Liebl, Wolfgang

doi:10.1128/jb.01023-10

Cited by 18 publications

(9 citation statements)

References 10 publications

(8 reference statements)

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“…PCC 8106 (LpcK), Spirochaeta thermophila DSM 6192 (SthK), and Leptospira biflexa serovar Patoc strain (LbiK). Among these species, Trichodesmium, Arthrospira, and Lyngbya belong to the genus of cyanobacteria or blue-green algae, whereas Spirochaeta thermophila is an extremely thermophilic bacterium (24) and Leptospira biflexa is a saprophytic pathogen (25). Alignment of these sequences using ClustalW (26) and further inspection revealed structural motifs that are common among members of the superfamily of voltage-gated K + channels (Fig.…”

Section: Resultsmentioning

confidence: 99%

Family of prokaryote cyclic nucleotide-modulated ion channels

Brams

Kusch

Spurný

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Cyclic nucleotide-modulated ion channels are molecular pores that mediate the passage of ions across the cell membrane in response to cAMP or GMP. Structural insight into this class of ion channels currently comes from a related homolog, MloK1, that contains six transmembrane domains and a cytoplasmic cyclic nucleotide binding domain. However, unlike eukaryote hyperpolarization-activated cyclic nucleotide-modulated (HCN) and cyclic nucleotide-gated (CNG) channels, MloK1 lacks a C-linker region, which critically contributes to the molecular coupling between ligand binding and channel opening. In this study, we report the identification and characterization of five previously unidentified prokaryote homologs with high sequence similarity (24-32%) to eukaryote HCN and CNG channels and that contain a C-linker region. Biochemical characterization shows that two homologs, termed AmaK and SthK, can be expressed and purified as detergent-solubilized protein from Escherichia coli membranes. Expression of SthK channels in Xenopus laevis oocytes and functional characterization using the patch-clamp technique revealed that the channels are gated by cAMP, but not cGMP, are highly selective for K + ions over Na + ions, generate a large unitary conductance, and are only weakly voltage dependent. These properties resemble essential properties of various eukaryote HCN or CNG channels. Our results contribute to an understanding of the evolutionary origin of cyclic nucleotide-modulated ion channels and pave the way for future structural and functional studies.cyclic AMP | cyclic GMP | electrophysiology | protein purification H yperpolarization-activated cyclic nucleotide-modulated (HCN) and cyclic nucleotide-gated (CNG) channels belong to the superfamily of voltage-gated K + channels. Both types of channels share a similar domain topology with six transmembrane domains, a Clinker region, and a cyclic nucleotide binding domain (CNBD). The S5-S6 segment forms the channel pore, including the selectivity filter for cations. The S4 segment contains several positively charged amino acids, suggesting that it acts as voltage sensor. Despite these similarities in sequence, the function of HCN and CNG channels is noticeably different: HCN channels activate upon membrane hyperpolarization and can be modulated by cyclic nucleotides. They are weakly selective for K + over Na + ions (for reviews, see refs. 1-3). In contrast, CNG channels are activated by the binding of cyclic nucleotides solely and their activity depends only weakly on voltage. The ionic current is carried by both monovalent and divalent cations (for reviews, see refs. 4 and 5).Insight into the structure of HCN channels has been gained only from crystal structures of the isolated intracellular C-linker and CNBD of mammalian HCN1, HCN2, HCN4, and invertebrate spHCN1. These parts of the channel assemble into tetramers (6-9). Further structural information comes from prokaryote ion channels that are homologous to HCN and CNG channels, such as the bacterial cyclic nucleotide-regula...

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Section: Resultsmentioning

confidence: 99%

Family of prokaryote cyclic nucleotide-modulated ion channels

Brams

Kusch

Spurný

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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“…Among isolated strains, S. thermophila , with an optimal growth temperature of 65°C, is the only one that can live on cellulose and hemicellulose substrates . However, genome sequencing revealed that S. thermophila is not equipped with typical cellulosomal proteins such as scaffoldins or cohesins . Instead, its chromosome comprises a broad set of 72 glycoside hydrolases (GH) of which 28 are presumably secretory enzymes.…”

Section: Introductionmentioning

confidence: 99%

Structural basis for cellulose binding by the type A carbohydrate‐binding module 64 of Spirochaeta thermophila

et al. 2016

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Spirochaeta thermophila secretes seven glycoside hydrolases for plant biomass degradation that carry a carbohydrate-binding module 64 (CBM64) appended at the C-terminus. CBM64 adsorbs to various β1-4-linked pyranose substrates and shows high affinity for cellulose. We present the first crystal structure of a CBM64 at 1.2 Å resolution, which reveals a jelly-roll-like fold corresponding to a surface-binding type A CBM. Modeling of its interaction with cellulose indicates that CBM64 achieves association with the hydrophobic face of β-linked pyranose chains via a unique coplanar arrangement of four exposed tryptophan side chains. Proteins 2016; 84:855-858. © 2016 Wiley Periodicals, Inc.

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“…Many new hyperthermophiles from bacteria and archaea have recently been isolated and the genomes of an increasing number have been sequenced [9-17], thus there are plenty of sequences can be obtained from the databases (http://www.ncbi.nlm.nih.gov/, http://www.cazy.org/). The genome sequence of Thermotoga thermarum was also reported last year (GenBank accession number: CP002351).…”

Section: Introductionmentioning

confidence: 99%

A novel highly thermostable xylanase stimulated by Ca2+ from Thermotoga thermarum: cloning, expression and characterization

Shi

Zhang

et al. 2013

Biotechnol Biofuels

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BackgroundXylanase is an important component of hemicellulase enzyme system. Since it plays an important role in the hydrolysis of hemicellulose into xylooligosaccharides (XOs), high thermostable xylanase has been the focus of much recent attention as powerful enzyme as well as in the field of biomass utilization.ResultsA xylanase gene (xyn10A) with 3,474 bp was cloned from the extremely thermophilic bacterium Thermotoga thermarum that encodes a protein containing 1,158 amino acid residues. Based on amino acid sequence homology, hydrophobic cluster and three dimensional structure analyses, it was attested that the xylanase belongs to the glycoside hydrolase (GH) families 10 with five carbohydrate binding domains. When the xylanase gene was cloned and expressed in Escherichia coli BL21 (DE3), the specific enzyme activity of xylanase produced by the recombinant strain was up to 145.8 U mg-1. The xylanase was optimally active at 95°C, pH 7.0. In addition, it exhibited high thermostability over broad range of pH 4.0-8.5 and temperature 55-90°C upon the addition of 5 mM Ca2+. Confirmed by Ion Chromatography System (ICS) analysis, the end products of the hydrolysis of beechwood xylan were xylose, xylobiose, xylotriose, xylotetraose, xylopentaose and xylohexaose.ConclusionsThe xylanase from T. thermarum is one of the hyperthermophilic xylanases that exhibits high thermostability, and thus, is a suitable candidate for generating XOs from cellulosic materials such as agricultural and forestry residues for the uses as prebiotics and precursors for further preparation of furfural and other chemicals.

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Genome Sequence of the Polysaccharide-Degrading, Thermophilic Anaerobe Spirochaeta thermophila DSM 6192

Cited by 18 publications

References 10 publications

Family of prokaryote cyclic nucleotide-modulated ion channels

Family of prokaryote cyclic nucleotide-modulated ion channels

Structural basis for cellulose binding by the type A carbohydrate‐binding module 64 of Spirochaeta thermophila

A novel highly thermostable xylanase stimulated by Ca2+ from Thermotoga thermarum: cloning, expression and characterization

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