Abstract
The structures of two major phosphoglycolipids from the thermophilic bacteria Thermus oshimai NTU-063, Thermus thermophilus NTU-077, Meiothermus ruber NTU-124, and Meiothermus taiwanensis NTU-220 were determined using spectroscopic and chemical analyses to be 2'-O-(1,2-diacyl-sn-glycero-3-phospho) -3'-O-(alpha-N-acetyl-glucosaminyl)-N-glyceroyl alkylamine [PGL1 (1)] and the novel structure 2'-O-(2-acylalkyldio-1-O-phospho)-3'-O-(alpha-N-acetylglucosaminyl)-N-glyceroyl alkylamine [PGL2 (2)]. PGL2 (2) is the first phosphoglycolipid identified with a 2-acylalkyldio-1-O-phosphate moiety. The fatty acids of the phosphoglycolipids are mainly iso-C(15:0), -C(16:0), and -C(17:0) and anteiso-C(15:0) and -C(17:0). The ratios of PGL2 (2) to PGL1 (1) are significantly altered when grown at different temperatures for three strains, T. thermophilus NTU-077, M. ruber NTU-124, and M. taiwanensis NTU-220, but not for T. oshimai NTU-063. Accordingly, the ratios of iso- to anteiso-branched fatty acids increase when grown at the higher temperature.
Highlights
The structures of two major phosphoglycolipids from the thermophilic bacteria Thermus oshimai NTU-063, Thermus thermophilus NTU-077, Meiothermus ruber NTU-124, and Meiothermus taiwanensis NTU-220 were determined using spectroscopic and chemical analyses to be 29-O-(1,2diacyl-sn-glycero-3-phospho) -39-O-(a-N-acetyl-glucosaminyl)N-glyceroyl alkylamine [PGL1 [1]] and the novel structure 29-O-(2-acylalkyldio-1-O-phospho)-39-O-(a-N-acetylglucosaminyl)-N-glyceroyl alkylamine [29-O-(2-acylalkyldio1-O-phospho)-39-O-(a-N-acetylglucosaminyl)-N-glyceroyl alkylamine (PGL2) [2]]
NMR spectra of samples in CDCl3/ CD3OD (99:1, v/v) were recorded on Bruker Avance 400 and 600 spectrometers at 300 K, with standard pulse sequences provided by Bruker, except for two-dimensional (2D) 1H-31P gradient heteronuclear multiple quantum coherence, which was modified from the pulse program hmqcgpqf with gradient strength calculated from the gyromagnetic ratios of 1H and 31P so that G1 5 G2 5 3 G3
One-dimensional and 2D total correlation spectroscopy (TOCSY) spectra were recorded with mixing times of 80–250 ms, which allows proton chemical shifts of carbohydrates to be assigned. 2D double quantum filtered-correlation spectroscopy (DQF-COSY) spectra were recorded in the analysis of carbohydrate coupling constants. 2D 1H-13C gradient heteronuclear multiple bond correlation spectra were recorded with 2J or 3J H-C coupling constants at 8 and 5 Hz, 2D 1H-13C gradient heteronuclear multiple quantum coherence (gHMQC) spectra were recorded with 1J H-C coupling constants at 145 Hz, and 2D 1H-31P gHMQC spectra were recorded with 3J H-P coupling constants at 10 Hz. 2D rotational frame nuclear Overhauser effect spectroscopy (ROESY) spectra were recorded with mixing times of 200 to 500 ms for conformation analysis
Summary
The structures of two major phosphoglycolipids from the thermophilic bacteria Thermus oshimai NTU-063, Thermus thermophilus NTU-077, Meiothermus ruber NTU-124, and Meiothermus taiwanensis NTU-220 were determined using spectroscopic and chemical analyses to be 29-O-(1,2diacyl-sn-glycero-3-phospho) -39-O-(a-N-acetyl-glucosaminyl)N-glyceroyl alkylamine [PGL1 [1]] and the novel structure 29-O-(2-acylalkyldio-1-O-phospho)-39-O-(a-N-acetylglucosaminyl)-N-glyceroyl alkylamine [PGL2 [2]]. When Escherichia coli, Thermus aquaticus, Candida species, thermophilic Bacillus species, and Staphylococcus aureus are grown at high temperatures, the proportion of branched-chain fatty acids increases and the proportions of monoenoic and heptanoic fatty acids decrease [2]. Thermus and Meiothermus species are Gram-negative thermophilic rods isolated from thermal hot springs, industrial and domestic water traps, and hydrothermal vents with neutral to alkaline pH [6]. In these species, polar lipids occupy a large proportion of the cellular membrane fractions and usually include a major phospholipid, a major glycolipid, and minor phospholipids and glycolipids [7, 8]. The highly radiation-resistant bacterium Deinococcus radiodurans, which is phylogenetically closely related to Thermus and Meiothermus [17], contains the phosphoglycolipids 29-O-(1,2-diacyl-sn-glycero3-phospho)-39-O-(a-galactosyl)-N-glyceroyl alkylamine [18]
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