Genome Sequence of the Early 20th-Century Extreme Halophile Halobacterium sp. Strain NRC-34001

Halobacterium sp. strain NRC-34001 is a red, extremely halophilic archaeon isolated in Canada in 1934. Single-molecule real-time sequencing revealed a 2.3-Mbp genome with a 2-Mbp chromosome and two plasmids (235 kb and 43 kb). The genome encodes all conserved core haloarchaeal groups (cHOGs) and a highly acidic proteome.

The Inducible Intein-Mediated Self-Cleaving Tag (IIST) System: A Novel Purification and Amidation System for Peptides and Proteins

An efficient self-cleavable purification tag could be a powerful tool for purifying recombinant proteins and peptides without additional proteolytic processes using specific proteases. Thus, the intein-mediated self-cleavage tag was developed and has been commercially available as the IMPACT™ system. However, uncontrolled cleavages of the purification tag by the inteins in the IMPACT™ system have been reported, thereby reducing final yields. Therefore, controlling the protein-splicing activity of inteins has become critical. Here we utilized conditional protein splicing by salt conditions. We developed the inducible intein-mediated self-cleaving tag (IIST) system based on salt-inducible protein splicing of the MCM2 intein from the extremely halophilic archaeon, Halorhabdus utahensis and applied it to small peptides. Moreover, we described a method for the amidation using the same IIST system and demonstrated 15N-labeling of the C-terminal amide group of a single domain antibody (VHH).

Complete Genome Sequence of an Extremely Halophilic Archaeon from Great Salt Lake, Halobacterium sp. GSL-19

An extremely halophilic archaeon, Halobacterium sp. strain GSL-19, was isolated from the north arm of Great Salt Lake in Utah. Single-molecule real-time (SMRT) sequencing was used to establish a GC-rich 2.3-Mbp genome composed of a circular chromosome and 2 plasmids, with 2,367 predicted genes, including 1 coding a CTAG-methylase widely distributed among Haloarchaea .

Characterization of 3-isopropylmalate dehydrogenase from extremely halophilic archaeon Haloarcula japonica

3-Isopropylmalate dehydrogenase (IPMDH) catalyzes oxidative decarboxylation of (2R, 3S)-3-isopropylmalate to 2-oxoisocaproate in leucine biosynthesis. In this study, recombinant IPMDH (HjIPMDH) from an extremely halophilic archaeon, Haloarcula japonica TR-1, was characterized. Activity of HjIPMDH increased as KCl concentration increased, and the maximum activity was observed at 3.0 M KCl. Analytical ultracentrifugation revealed that HjIPMDH formed a homotetramer at high KCl concentrations, and it dissociated to a monomer at low KCl concentrations. Additionally, HjIPMDH was thermally stabilized by higher KCl concentrations. This is the first report on haloarchaeal IPMDH.

Characterisation of a carotenoid producing extremely halophilic archaeon Halorubrum sodomense MS5.1 isolated from a solar saltern in Tamil Nadu, South India

A carotenoid producing extremely halophilic archaeon designated MS5.1 was isolated out of brine samples from a crystalliser pond of a marine solar saltern in Kanyakumari District, Tamil Nadu, South India. The red pigmented, long rod shaped haloarchaeon was found to be able to grow at temperature range of 20-40°C, salt concentration of 10-35% and pH range of 6 to 9 with optimum conditions for growth being 28°C; 30% salt and pH 7. The archaeal cells were found to be Gram negative and got lysed when placed in distilled water. Analysis of 16S rDNA sequence revealed that the isolate is phylogenetically related to species of the genus Halorubrum under the family Halobacteriaceae, with close relationship to Halorubrum sodomense. Further analyses of the phenotypic and biochemical characteristics of the isolate confirmed the identity of the organism as Halorubrum sodemense. The gene sequence of the strain was deposited in the NCBI GenBank with Accession No. MW332265. Polar lipid characterisation of the strain by thin layer chromatography (TLC) identified the major polar lipids as Phosphatidylglycerol (PG), Phosphatidylglycerol phosphate methyl ester (PGP-Me), Diglycosyl archaeol (DGA) and Sulfated diglycosyl archaeol (S-DGA). The strain was further screened for antibiotic sensitivity and found insensitive to antibiotics that target peptidoglycan layer and found sensitive only to Nitrofurantoin and Rifampicin, which works by inhibiting nucleic acid synthesis. As halophilic archaea are known natural sources of carotenoids, an attempt was made to extract these pigments from the cells and analysed by UV-VIS spectroscopy. Present study characterised the haloarchaeal strain H. sodomense MS5.1 isolated from a coastal solar saltern, optimised the growth conditions and the results clearly indicated that the strain is a potential source of carotenoids and halophilic enzymes.

Characterization of a GlgC homolog from extremely halophilic archaeon Haloarcula japonica

ABSTRACT Glycogen synthesis in bacteria is mainly organized by the products of glgB, glgC, and glgA genes comprising the widely known glg operon. On the genome of extremely halophilic archaeon Haloarcula japonica, there was a gene cluster analogous to the bacterial glg operon. In this study, we focused on a GlgC homolog of Ha. japonica, and its recombinant enzyme was prepared and characterized. The enzyme showed highest activity toward GTP and glucose-1-phosphate as substrates in the presence of 2.6 m KCl and predicted to be work as “GDP-glucose pyrophosphorylase” in Ha. japonica.