[Show abstract][Hide abstract] ABSTRACT: The structure of membrane lipids in Archaea is different from those of Bacteria and Eucarya in many ways including the chirality of the glycerol backbone. Until now, heterochiral membranes were believed to be unstable; thus, no cellular organism could have existed before the separation of the groups of life. In this study, we tested the formation of heterochiral hybrid membrane made of Bacterial sn-glycerol-3-phosphate-type polar lipid and Archaeal sn-glycerol-1-phosphate-type polar lipid using the fluorescence probe. The stability of the hybrid liposomes made of phosphatidylethanolamines or phosphatidylcholines or polar lipids of thermophilic Bacteria and polar lipids of Archaea were investigated. The hybrid liposomes are all stable compared with homochiral liposome made of dimyristoylphosphatidylethanolamine and dipalmitoylphosphatidylcholine. However, the stability was drastically changed with increasing carbon chain length. Accordingly, "chirality" may not be but chain length is important. From these results, we suggest that the heterochiral hybrid membrane could be used as the membrane lipid for the last universal common ancestor (Commonote) before the emergence of Archaea and Bacteria.
[Show abstract][Hide abstract] ABSTRACT: We have tested effects of various factors in space environment on survivability of Deinococcus spp. including our newly isolated species at high altitude. In "Tanpopo" mission, we are planning to expose microorganisms such as deinococcal species.
[Show abstract][Hide abstract] ABSTRACT: A pink-red pigmented, non-motile, coccoid bacterial strain, ST0316(T), was isolated from dust samples collected from the stratosphere in Japan. Phylogenetic analysis based on 16S rRNA gene sequences showed that it belonged to the genus Deinococcus. DNA G+C content (69.8 mol%), desiccation tolerance, and resistance to gamma-rays [D(10) (dose required to reduce the bacterial population by 10-fold) >8 kGy] and UV radiation (D(10) 1000 J m(-2)) supported the affiliation of strain ST0316(T) to the genus Deinococcus. The major peptidoglycan amino acids were d-glutamic acid, glycine, d-alanine, l-alanine and ornithine. Predominant fatty acids were C(16 : 1)omega7c, C(16 : 0), C(17 : 0) and iso-C(17 : 0). Strain ST0316(T) diverged from recognized species of the genus Deinococcus, showing less than 93.0 % similarity values to its closest relatives Deinococcus apachensis, D. aerius, D. geothermalis and D. murrayi. Strain ST0316(T) also differed from the type strains of closely related species in its polar lipid profile, nitrate reduction and carbon-source assimilation tests. Therefore, we propose a new species of the genus Deinococcus, Deinococcus aetherius sp. nov. (type strain, ST0316(T) =JCM 11751(T) =DSM 21230(T)).
International journal of systematic and evolutionary microbiology 08/2009; 60(Pt 4):776-9. · 2.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: An orange-pigmented, non-motile, coccoid bacterial strain, designated TR0125T, was isolated from dust samples collected in the high atmosphere above Japan. Phylogenetic analysis based on 16S rRNA gene sequences showed that the strain was within the radiation of Deinococcus species. The major peptidoglycan amino acids were D-glutamic acid, glycine, D-alanine, L-alanine and ornithine. The predominant fatty acids were iso-C17:0, iso-C17:1omega9c and iso-C15:0. Strong resistance to desiccation, UV-C and gamma radiation and high DNA G+C content also supported the affiliation of strain TR0125T to the genus Deinococcus. Strain TR0125T showed the highest 16S rRNA gene sequence similarity value (95.7%) to the type strain of Deinococcus apachensis, and phylogenetic analysis showed that it was further separated from D. apachensis than from Deinococcus geothermalis, indicating that strain TR0125T was not a member of these two Deinococcus species. In addition, phenotypic differences were found between strain TR0125T and the type strains of these two Deinococcus species. Therefore, a novel species of the genus Deinococcus, Deinococcus aerius sp. nov. (type strain, TR0125T=JCM 11750T=DSM 21212T), is proposed to accommodate this isolate.
International journal of systematic and evolutionary microbiology 07/2009; 59(Pt 8):1862-6. · 2.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Thermoplasma acidophilum HO-62 was grown at different pHs and temperatures, and its polar lipid compositions were determined. Although the number of cyclopentane rings in the caldarchaeol moiety increased when T. acidophilum was cultured at high temperature, the number decreased at low pHs. Glycolipids, phosphoglycolipids, and phospholipids were analyzed by high-performance liquid chromatography with an evaporative light-scattering detector. The amount of caldarchaeol with more than two sugar units on one side increased under low-pH and high-temperature conditions. The amounts of glycolipids increased and those of phosphoglycolipids decreased under these conditions. The proton permeability of the liposomes obtained from the phosphoglycolipids that contained two or more sugar units was lower than that of the liposomes obtained from the phosphoglycolipids that contained one sugar unit. From these results, we propose the hypothesis that T. acidophilum adapts to low pHs and high temperatures by extending sugar chains on their cell surfaces, as well as by varying the number of cyclopentane rings.
Journal of bacteriology 09/2008; 190(15):5404-11. · 3.94 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Polar lipid biosynthesis in the thermoacidophilic archaeon Thermoplasma acidophilum was analyzed using terbinafine, an inhibitor of tetraether lipid biosynthesis. Cells of T. acidophilum were labeled with [(14)C]mevalonic acid, and their lipids were extracted and analyzed by two-dimensional thin-layer chromatography. Lipids labeled with [(14)C]mevalonic acid, [(14)C]glycerol, and [(32)P]orthophosphoric acid were extracted and hydrolyzed under different conditions to determine the structure of polar lipids. The polar lipids were estimated to be archaetidylglycerol, glycerophosphatidylcaldarchaetidylglycerol, caldarchaetidylglycerol, and beta- l-gulopyranosylcaldarchaetidylglycerol, the main polar lipid of T. acidophilum. Pulse and chase experiments with terbinafine revealed that one tetraether lipid molecule is synthesized by head-to-head condensation of two molecules of archaetidylglycerol and that a sugar group of tetraether phosphoglycolipid is expected to attach to the tetraether lipid core after head-to-head condensation in T. acidophilum. A precursor accumulated in the presence of terbinafine with a fast-atom-bombardment mass spectrometry peak m/z 806 was compatible with archaetidylglycerol. The relative height of the peak m/z 806 decreased after removal of the inhibitor. The results suggest that most of the precursor, archaetidylglycerol, is in fully saturated form.
[Show abstract][Hide abstract] ABSTRACT: Polar ether lipids of Thermoplasma acidophilum HO-62 were purified by high-performance liquid chromatography with an evaporative light-scattering detector. Structures of purified lipids were investigated by capillary gas chromatography, mass spectrometry, and nuclear magnetic resonance. Three types of ether lipids were found: phospholipids, glycolipids, and phosphoglycolipids. The two phospholipids had glycerophosphate as the phosphoester moiety. The seven glycolipids had different combinations of gulose, mannose, and glucose, which formed mono- or oligosaccharides. The eight phosphoglycolipids with two polar head groups contained glycerophosphate as the phosphoester moiety and gulose alone or gulose and mannose, which formed mono- or oligosaccharides, as the sugar moiety. Although gulose is an unusual sugar in nature, several glyco- and phosphoglycolipids contained gulose as one of the sugar moieties in Thermoplasma acidophilum. All the ether lipids had isopranoid chains of C(40) or C(20) with zero to three cyclopentane rings. The structures of these lipids including four new glycolipids and three new phosphoglycolipids were determined, and a glycosylation process for biosynthesis of these glycolipids was suggested.
Journal of Bacteriology 02/2002; 184(2):556-63. · 3.19 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Quinones of Thermoplasma acidophilum HO-62 were analyzed by high-performance liquid chromatography, mass spectrometry, and nuclear magnetic resonance. Menaquinone, methionaquinone, and 2-trans and 2-cis forms of thermoplasmaquinone were identified. The relative amount of thermoplasmaquinone increased under anaerobic conditions, and those of menaquinone and methionaquinone increased under aerobic conditions.
Journal of Bacteriology 03/2001; 183(4):1462-5. · 3.19 Impact Factor