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Metabolism of halophilic archaea.

Falb M, Müller K, Königsmaier L, Oberwinkler T, Horn P, von Gronau S, Gonzalez O, Pfeiffer F, Bornberg-Bauer E, Oesterhelt D - Extremophiles (2008)

Bottom Line: In spite of their common hypersaline environment, halophilic archaea are surprisingly different in their nutritional demands and metabolic pathways.The comparative study reveals different sets of enzyme genes amongst halophilic archaea, e.g. in glycerol degradation, pentose metabolism, and folate synthesis.The carefully assessed metabolic data represent a reliable resource for future system biology approaches as it also links to current experimental data on (halo)archaea from the literature.

View Article: PubMed Central - PubMed

Affiliation: Department of Membrane Biochemistry, Max-Planck-Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany.

ABSTRACT
In spite of their common hypersaline environment, halophilic archaea are surprisingly different in their nutritional demands and metabolic pathways. The metabolic diversity of halophilic archaea was investigated at the genomic level through systematic metabolic reconstruction and comparative analysis of four completely sequenced species: Halobacterium salinarum, Haloarcula marismortui, Haloquadratum walsbyi, and the haloalkaliphile Natronomonas pharaonis. The comparative study reveals different sets of enzyme genes amongst halophilic archaea, e.g. in glycerol degradation, pentose metabolism, and folate synthesis. The carefully assessed metabolic data represent a reliable resource for future system biology approaches as it also links to current experimental data on (halo)archaea from the literature.

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Biosynthesis of isoprenoids in halophilic archaea. The isoprenoid precursor IPP is synthesized via the mevalonate pathway as shown by labeling studies (green reaction exists, red reaction absent, bold experimental verification). Various isoprenoids detected in membranes of H. salinarum (listed in boxes) are synthesized by a series of condensation reactions with IPP, which is added in head–tail (HT) or head–head (HH) fashion, and through desaturase reactions ([2H]). Enzyme gene sets for isoprenoid synthesis differ only slightly between halorarchaea (square: H. marismortui, circle: H. walsbyi, diamond: N. pharaonis, triangle: H. salinarum, green gene exists, red gene absent). Bacterial- (B) or archaeal-type (A) enzyme variants are indicated. Superscript “a” indicates C5-prenyl units are synthesized via the mevalonate pathway starting from two acetyl-CoA molecules and a still unknown C2-unit arising from amino acid degradation (Ekiel et al. 1986)
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Fig3: Biosynthesis of isoprenoids in halophilic archaea. The isoprenoid precursor IPP is synthesized via the mevalonate pathway as shown by labeling studies (green reaction exists, red reaction absent, bold experimental verification). Various isoprenoids detected in membranes of H. salinarum (listed in boxes) are synthesized by a series of condensation reactions with IPP, which is added in head–tail (HT) or head–head (HH) fashion, and through desaturase reactions ([2H]). Enzyme gene sets for isoprenoid synthesis differ only slightly between halorarchaea (square: H. marismortui, circle: H. walsbyi, diamond: N. pharaonis, triangle: H. salinarum, green gene exists, red gene absent). Bacterial- (B) or archaeal-type (A) enzyme variants are indicated. Superscript “a” indicates C5-prenyl units are synthesized via the mevalonate pathway starting from two acetyl-CoA molecules and a still unknown C2-unit arising from amino acid degradation (Ekiel et al. 1986)

Mentions: Membrane lipids of archaea consist of glycerol diether lipids with prenyl side chains instead of diacylglycerol esters. Specifically, membranes of H. salinarum contain core lipids with two phytanyl side chains (C20), and to lesser extents also other isoprenoid constituents such as squalenes (C30), phytoenes (C40), menaquinones (C40), and dolichol (C60) (Oesterhelt 1976; Lechner et al. 1985; Kushwaha et al. 1976) (Fig. 3). Furthermore, H. salinarum synthesizes several carotenoids from prenyl precursors, preferentially bacterioruberins (C50) and photoactive retinal (C20) (Oesterhelt 1976; Oesterhelt and Stoeckenius 1973). Retinal is incorporated into bacteriorhodopsin and other retinal proteins, which are unique to haloarchaea within the archaeal domain of life. Although fatty acids are not part of archaeal membrane lipids, small amounts of fatty acids (C14, C16, C18) have been detected in membrane proteins of H. salinarum (Pugh and Kates, 1994). Other haloarchaeal species likely possess similar membrane constituents as H. salinarum because they have the same gene set for the de novo synthesis of isoprenoids. However, specific prenyl-based compounds might vary from species to species, as in the case of diether core lipids found in haloalkaliphiles, e.g. N. pharaonis (C20–C20 and C20–C25 prenyl chains) (Tindall et al. 1984).Fig. 3


Metabolism of halophilic archaea.

Falb M, Müller K, Königsmaier L, Oberwinkler T, Horn P, von Gronau S, Gonzalez O, Pfeiffer F, Bornberg-Bauer E, Oesterhelt D - Extremophiles (2008)

Biosynthesis of isoprenoids in halophilic archaea. The isoprenoid precursor IPP is synthesized via the mevalonate pathway as shown by labeling studies (green reaction exists, red reaction absent, bold experimental verification). Various isoprenoids detected in membranes of H. salinarum (listed in boxes) are synthesized by a series of condensation reactions with IPP, which is added in head–tail (HT) or head–head (HH) fashion, and through desaturase reactions ([2H]). Enzyme gene sets for isoprenoid synthesis differ only slightly between halorarchaea (square: H. marismortui, circle: H. walsbyi, diamond: N. pharaonis, triangle: H. salinarum, green gene exists, red gene absent). Bacterial- (B) or archaeal-type (A) enzyme variants are indicated. Superscript “a” indicates C5-prenyl units are synthesized via the mevalonate pathway starting from two acetyl-CoA molecules and a still unknown C2-unit arising from amino acid degradation (Ekiel et al. 1986)
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2262144&req=5

Fig3: Biosynthesis of isoprenoids in halophilic archaea. The isoprenoid precursor IPP is synthesized via the mevalonate pathway as shown by labeling studies (green reaction exists, red reaction absent, bold experimental verification). Various isoprenoids detected in membranes of H. salinarum (listed in boxes) are synthesized by a series of condensation reactions with IPP, which is added in head–tail (HT) or head–head (HH) fashion, and through desaturase reactions ([2H]). Enzyme gene sets for isoprenoid synthesis differ only slightly between halorarchaea (square: H. marismortui, circle: H. walsbyi, diamond: N. pharaonis, triangle: H. salinarum, green gene exists, red gene absent). Bacterial- (B) or archaeal-type (A) enzyme variants are indicated. Superscript “a” indicates C5-prenyl units are synthesized via the mevalonate pathway starting from two acetyl-CoA molecules and a still unknown C2-unit arising from amino acid degradation (Ekiel et al. 1986)
Mentions: Membrane lipids of archaea consist of glycerol diether lipids with prenyl side chains instead of diacylglycerol esters. Specifically, membranes of H. salinarum contain core lipids with two phytanyl side chains (C20), and to lesser extents also other isoprenoid constituents such as squalenes (C30), phytoenes (C40), menaquinones (C40), and dolichol (C60) (Oesterhelt 1976; Lechner et al. 1985; Kushwaha et al. 1976) (Fig. 3). Furthermore, H. salinarum synthesizes several carotenoids from prenyl precursors, preferentially bacterioruberins (C50) and photoactive retinal (C20) (Oesterhelt 1976; Oesterhelt and Stoeckenius 1973). Retinal is incorporated into bacteriorhodopsin and other retinal proteins, which are unique to haloarchaea within the archaeal domain of life. Although fatty acids are not part of archaeal membrane lipids, small amounts of fatty acids (C14, C16, C18) have been detected in membrane proteins of H. salinarum (Pugh and Kates, 1994). Other haloarchaeal species likely possess similar membrane constituents as H. salinarum because they have the same gene set for the de novo synthesis of isoprenoids. However, specific prenyl-based compounds might vary from species to species, as in the case of diether core lipids found in haloalkaliphiles, e.g. N. pharaonis (C20–C20 and C20–C25 prenyl chains) (Tindall et al. 1984).Fig. 3

Bottom Line: In spite of their common hypersaline environment, halophilic archaea are surprisingly different in their nutritional demands and metabolic pathways.The comparative study reveals different sets of enzyme genes amongst halophilic archaea, e.g. in glycerol degradation, pentose metabolism, and folate synthesis.The carefully assessed metabolic data represent a reliable resource for future system biology approaches as it also links to current experimental data on (halo)archaea from the literature.

View Article: PubMed Central - PubMed

Affiliation: Department of Membrane Biochemistry, Max-Planck-Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany.

ABSTRACT
In spite of their common hypersaline environment, halophilic archaea are surprisingly different in their nutritional demands and metabolic pathways. The metabolic diversity of halophilic archaea was investigated at the genomic level through systematic metabolic reconstruction and comparative analysis of four completely sequenced species: Halobacterium salinarum, Haloarcula marismortui, Haloquadratum walsbyi, and the haloalkaliphile Natronomonas pharaonis. The comparative study reveals different sets of enzyme genes amongst halophilic archaea, e.g. in glycerol degradation, pentose metabolism, and folate synthesis. The carefully assessed metabolic data represent a reliable resource for future system biology approaches as it also links to current experimental data on (halo)archaea from the literature.

Show MeSH
Related in: MedlinePlus