CDP-2,3-Di -O- Geranylgeranyl- sn -Glycerol: l -Serine O -Archaetidyltransferase (Archaetidylserine Synthase) in the Methanogenic Archaeon Methanothermobacter thermautotrophicus

Abstract

thermautotrophicus genome annotated as the gene encoding phosphatidylserine synthase was found to be homologous to Bacillus subtilis pssA but not to Escherichia coli pssA. The substrate specificity of phosphatidylserine synthase from B. subtilis was quite similar to that observed for the M. thermautotrophicus archaetidylserine synthase, while the E. coli enzyme had a strong preference for CDP-1,2-diacyl-sn-glycerol. It was concluded that M. thermautotrophicus archaetidylserine synthase belongs to subclass II phosphatidylserine synthase (B. subtilis type) on the basis of not only homology but also substrate specificity and some enzymatic properties. The possibility that a gene encoding the subclass II phosphatidylserine synthase might be transferred from a bacterium to an ancestor of methanogens is discussed.

Recent Advances in Structural Research on Ether Lipids from Archaea Including Comparative and Physiological Aspects

“…The biosynthetic intermediates of ether polar lipids in archaea include geranylgeranyl ether lipids, which are a kind of allyl ethers. [78][79][80][81] If a stable saturated ether bond is essential for survival at high temperatures and unstable allyl ether bonds are degraded at those temperatures, the organism cannot survive at high temperatures because a trace amount of the unstable allyl ether intermediates would be degraded and the stable lipid could not be synthesized at high temperatures. It can, therefore, be concluded that stable ether bonds are not a result of adaptation to hot environments.…”

A Novel Biosynthetic Pathway of Archaetidyl-myo-inositol via Archaetidyl-myo-inositol Phosphate from CDP-archaeol and d-Glucose 6-Phosphate in Methanoarchaeon Methanothermobacter thermautotrophicus Cells

“…In addition, electron impact-mass spectrometry of the first main peak gave a signal of m/z 633 (M-CH 3 ) ϩ , which is consistent with the molecular weight of IP(TMS) 5 Me 2 . The second and third main peaks were confirmed to be glucose 6-phosphate(TMS) 4 Me 2 by electron impact-mass spectrometry (m/z 561 (M-CH 3 ) ϩ ). Thus, the product of the IP synthase reaction was decisively determined to be 1L-myo-inositol 1-phosphate.…”

“…The precipitated protein was removed by centrifugation, and the supernatant was incubated at 37°C for 1 h with 0.2 M NaIO 4 . Then 1 M Na 2 SO 3 was added to destroy excess NaIO 4 , and liberated P i was measured using the method of Barnett (21). The net P i value was obtained by subtraction of the blank value of the reaction mixture that received Na 2 SO 3 before the addition of NaIO 4 .…”

“…Then 1 M Na 2 SO 3 was added to destroy excess NaIO 4 , and liberated P i was measured using the method of Barnett (21). The net P i value was obtained by subtraction of the blank value of the reaction mixture that received Na 2 SO 3 before the addition of NaIO 4 . For structure identification of the reaction product, an IP synthase preparation partially purified by ammonium sulfate fractionation (50 -70%) was used because low molecular weight compounds in the cell homoge-nates may interfere with gas liquid chromatography (GLC) analyses of the products.…”

“…The major polar lipids of the archaeon are L-serine, ethanolamine, or myo-inositol-containing diand tetraether-type phospholipids and phosphoglycolipids and gentiobiose-containing di-and tetraether-type glycolipids. The biosynthetic pathways of diether-type serine-phospholipid (archaetidylserine) and diether-type glycolipid (gentiobiosyl archaeol) were previously elucidated in vitro (3,4). The pathway begins with the formation of the enantiomeric glycerophosphate (sn-glycerol 1-phosphate) from dihydroxyacetone phosphate (5).…”