Bacteriohopanepolyol

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Bacteriohopanepolyols (BHPs), bacteriohopanoids, or bacterial pentacyclic triterpenoids are commonly found in the lipid cell membranes of bacteria. [1] BHPs are frequently used as biomarkers in sedimentary rocks and can provide paleoecological information about ancient bacterial communities. [2]

Contents

Function

Several studies have suggested that bacteriohopanepolyols play a role in the structure of membranes due to their polycylic structures and amphiphilic properties. [3] [4] BHPs have been hypothesized to be an evolutionary precursor to sterols, a class of biochemical compounds which is primarily present in eukaryotic cell membranes. [5] The presence of BHPs in membranes has been found to improve the temperature, [6] antimicrobial resistance, and pH tolerance [7] of bacteria.

Additionally, BHPs have been found to be an important constituent of 'lipid rafts', which are enriched in specific lipids and provide transport, protein synthesis, and signal transduction proteins. Prior to their discovery in bacteria, lipid rafts were considered a key piece of the evolution of more complex, eukaryotic cells. [8]

Sources

Bacteriohopanepolyols have been found to be present in all types of sediment since their discovery in 1979, [9] [10] and are produced by a wide range of bacteria including alpha-, beta-, cyano-, and gammaproteobacteria [11] While early studies estimated that around half of all species of bacteria produce hopanoids, [5] more recent studies estimate around 4% of bacteria have the ability to produce hopanoids. [12]

Several studies have used culture-independent methods to survey bacterial genomes for genes which may imply the ability to produce BHPs [13] [12] The squalene-hopene cyclase gene (sqhC) produces an enzyme that catalyzes the cyclization of squalene, a precursor of BHPs. Among thirty sequenced bacteria, this gene was found in the genomes of all hopanoid-containing bacteria, and very few of the bacteria which do not produce hopanoids, and therefore the presence of the sqhC gene was assumed to mean that the gene was expressed. Overall, fewer than ten-percent of the marine and freshwater bacterioplankton were found to possess this gene. [9]

Analysis

Bacteriohopanepolyols are commonly identified through chemical extraction of organic matter followed by analysis on a mass spectrometer. [14] Extraction protocols are intended to purify natural samples to allow for analysis of a simpler mixture of compounds. Differences in the efficiency of extraction methods have been found to vary for different types of BHPs. [15] [16]

BHPs were first analyzed using a gas chromatograph mass spectrometer (GC-MS), [17] however the use of HPLC-MS methods have become more common in recent years due to the ability to analyze BHPs without the Rohmer preparation procedure which resulted in a loss of specificity. [14] Despite its advantages, analysis of BHPs using HPLC-MS is complicated by a lack of sufficient standards and variations in the efficiency of acetylation among different BHPs. [14]

Biomarker utility

The polycyclic hydrocarbon skeleton of BHPs makes them resistant to degradation, and allows for them to be preserved for long periods of time in the geologic record. [9] However, the use of BHPs as a biomarker for a specific group of bacteria is limited by the current state of knowledge regarding the identification of groups of bacteria which produce specific bacteriohopanepolyols. Some BHPs may be produced by a diverse range of organisms, such as bacteriohopane-32,33,34,35-tetrol (BHT), [5] and the biological source of many BHPs is uncertain, complicating interpretation of BHPs.

Initially, BHPs were thought to only be present in aerobic bacteria, [18] [5] however they have since been found in anaerobic bacteria. [19] [20] BHPs have often been used as an indicator for cyanobacteria, [21] and forty-nine out of fifty-eight cultured cyanobacteria have been found to produce BHP. [11] In particular, 2β-methylbiohopanoids has only been found to be produced in significant quantities by cyanobacteria. [21]

An isomer of bacteriohopanetetrol was found to be associated with anoxic and suboxic conditions in marine pelagic sediments. [20] Bacteriohopanepolyol identification has been paired with stable carbon isotope analysis, for greater specificity. [13] In particular, the detection of 3-methylhopanoids (hopanoids with a methyl group at the C3 position) which are highly depleted in 13C are interpreted as a proxy for methanotrophy. [18]

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<span class="mw-page-title-main">Squalene</span> Chemical compound

Squalene is an organic compound. It is a triterpene with the formula C30H50. It is a colourless oil, although impure samples appear yellow. It was originally obtained from shark liver oil (hence its name, as Squalus is a genus of sharks). An estimated 12% of bodily squalene in humans is found in sebum. Squalene has a role in topical skin lubrication and protection.

<span class="mw-page-title-main">Geobiology</span> Study of interactions between Earth and the biosphere

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<span class="mw-page-title-main">Hopanoids</span> Class of chemical compounds

Hopanoids are a diverse subclass of triterpenoids with the same hydrocarbon skeleton as the compound hopane. This group of pentacyclic molecules therefore refers to simple hopenes, hopanols and hopanes, but also to extensively functionalized derivatives such as bacteriohopanepolyols (BHPs) and hopanoids covalently attached to lipid A.

TEX<sub>86</sub>

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<span class="mw-page-title-main">Cholestane</span> Chemical compound

Cholestane is a saturated tetracyclic triterpene. This 27-carbon biomarker is produced by diagenesis of cholesterol and is one of the most abundant biomarkers in the rock record. Presence of cholestane, its derivatives and related chemical compounds in environmental samples is commonly interpreted as an indicator of animal life and/or traces of O2, as animals are known for exclusively producing cholesterol, and thus has been used to draw evolutionary relationships between ancient organisms of unknown phylogenetic origin and modern metazoan taxa. Cholesterol is made in low abundance by other organisms (e.g., rhodophytes, land plants), but because these other organisms produce a variety of sterols it cannot be used as a conclusive indicator of any one taxon. It is often found in analysis of organic compounds in petroleum.

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<span class="mw-page-title-main">Squalene-hopene cyclase</span>

Squalene-hopene cyclase (SHC) (EC 5.4.99.17) or hopan-22-ol hydro-lyase is an enzyme in the terpene cyclase/mutase family. It catalyzes the interconversion of squalene into a pentacyclic triterpenes, hopene and hopanol. This enzyme catalyses the following chemical reactions.

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References

  1. ↑ Blumenberg M, Seifert R, Kasten S, Bahlamnn E, Michaelis W (2009). "Euphotic zone bacterioplankton sources major sedimentary bacteriohopanepolyols in the Holocene Black Sea". Geochimica et Cosmochimica Acta. 73 (3): 750–766. Bibcode:2009GeCoA..73..750B. doi:10.1016/j.gca.2008.11.005.
  2. ↑ van Winden JF, Talbot HM, Kip N, Reichart GJ, Pol A, McNamara NP, et al. (2012). "Bacteriohopanepolyol signatures as markers for methanotrophic bacteria in peat moss". Geochimica et Cosmochimica Acta. 77: 52–61. Bibcode:2012GeCoA..77...52V. doi:10.1016/j.gca.2011.10.026. hdl: 2066/93763 .
  3. ↑ Tanaka Y (January 1993). "Agroactive Compounds of Microbial Origin". Annual Review of Microbiology. 47 (1): 57–87. doi:10.1146/annurev.micro.47.1.57. ISSN   0066-4227. PMID   8257109.
  4. ↑ Ourisson G, Rohmer M, Poralla K (1987). "Prokaryotic hopanoids and other polyterpenoid sterol surrogates". Annual Review of Microbiology. 41: 301–333. doi:10.1146/annurev.mi.41.100187.001505. PMID   3120639.
  5. 1 2 3 4 Rohmer M, Bouvier-Nave P, Ourisson G (May 1984). "Distribution of Hopanoid Triterpenes in Prokaryotes". Microbiology. 130 (5): 1137–1150. doi: 10.1099/00221287-130-5-1137 . ISSN   1350-0872.
  6. ↑ Doughty DM, Coleman ML, Hunter RC, Sessions AL, Summons RE, Newman DK (November 2011). "The RND-family transporter, HpnN, is required for hopanoid localization to the outer membrane of Rhodopseudomonas palustris TIE-1". Proceedings of the National Academy of Sciences of the United States of America. 108 (45): E1045–E1051. doi: 10.1073/pnas.1104209108 . PMC   3215060 . PMID   21873238.
  7. ↑ Schmerk CL, Bernards MA, Valvano MA (December 2011). "Hopanoid production is required for low-pH tolerance, antimicrobial resistance, and motility in Burkholderia cenocepacia". Journal of Bacteriology. 193 (23): 6712–6723. doi:10.1128/JB.05979-11. PMC   3232912 . PMID   21965564.
  8. ↑ Bramkamp M, Lopez D (March 2015). "Exploring the existence of lipid rafts in bacteria". Microbiology and Molecular Biology Reviews. 79 (1): 81–100. doi:10.1128/MMBR.00036-14. PMC   4342107 . PMID   25652542.
  9. 1 2 3 Pearson A, Flood Page SR, Jorgenson TL, Fischer WW, Higgins MB (September 2007). "Novel hopanoid cyclases from the environment". Environmental Microbiology. 9 (9): 2175–2188. Bibcode:2007EnvMi...9.2175P. doi:10.1111/j.1462-2920.2007.01331.x. PMID   17686016.
  10. ↑ Ourissen G (1979). "The Hopanoids: palaeochemistry and biochemistry of a group of natural products". Pure Appl. Chem. 51 (4): 709–729. doi:10.1351/pac197951040709. S2CID   20809792.
  11. 1 2 Talbot HM, Summons RE, Jahnke LL, Cockell CS, Rohmer M, Farrimond P (February 2008). "Cyanobacterial bacteriohopanepolyol signatures from cultures and natural environmental settings". Organic Geochemistry. 39 (2): 232–263. Bibcode:2008OrGeo..39..232T. doi:10.1016/j.orggeochem.2007.08.006.
  12. 1 2 Pearson A, Rusch DB (March 2009). "Distribution of microbial terpenoid lipid cyclases in the global ocean metagenome". The ISME Journal. 3 (3): 352–363. Bibcode:2009ISMEJ...3..352P. doi: 10.1038/ismej.2008.116 . PMID   19037261.
  13. 1 2 Welander PV, Summons RE (August 2012). "Discovery, taxonomic distribution, and phenotypic characterization of a gene required for 3-methylhopanoid production". Proceedings of the National Academy of Sciences of the United States of America. 109 (32): 12905–12910. Bibcode:2012PNAS..10912905W. doi: 10.1073/pnas.1208255109 . PMC   3420191 . PMID   22826256.
  14. 1 2 3 Kusch S, Rush D (October 2022). "Revisiting the precursors of the most abundant natural products on Earth: A look back at 30+ years of bacteriohopanepolyol (BHP) research and ahead to new frontiers" (PDF). Organic Geochemistry. 172: 104469. Bibcode:2022OrGeo.17204469K. doi:10.1016/j.orggeochem.2022.104469.
  15. ↑ Herrmann (1996-01-15). "A non-extractable triterpenoid of the hopane series in Acetobacter xylinum". FEMS Microbiology Letters. 135 (2–3): 323–326. doi:10.1016/0378-1097(95)00473-4. ISSN   0378-1097.
  16. ↑ Berndmeyer C, Thiel V, Blumenberg M (April 2014). "Test of microwave, ultrasound and Bligh & Dyer extraction for quantitative extraction of bacteriohopanepolyols (BHPs) from marine sediments". Organic Geochemistry. 68: 90–94. Bibcode:2014OrGeo..68...90B. doi:10.1016/j.orggeochem.2014.01.003. ISSN   0146-6380.
  17. ↑ Depmeier W, Schmid H, Haenssler F (September 1980). "PdB2O4, the first palladium borate". Naturwissenschaften. 67 (9): 456. doi:10.1007/BF00405642. ISSN   0028-1042.
  18. 1 2 Talbot HM, Watson DF, Pearson EJ, Farrimond P (October 2003). "Diverse biohopanoid compositions of non-marine sediments". Organic Geochemistry. 34 (10): 1353–1371. Bibcode:2003OrGeo..34.1353T. doi:10.1016/S0146-6380(03)00159-1.
  19. ↑ Blumenberg M, Krüger M, Nauhaus K, Talbot HM, Oppermann BI, Seifert R, et al. (July 2006). "Biosynthesis of hopanoids by sulfate-reducing bacteria (genus Desulfovibrio)". Environmental Microbiology. 8 (7): 1220–1227. Bibcode:2006EnvMi...8.1220B. doi:10.1111/j.1462-2920.2006.01014.x. PMID   16817930.
  20. 1 2 Sáenz JP, Wakeham SG, Eglinton TI, Summons RE (December 2011). "New constraints on the provenance of hopanoids in the marine geologic record: Bacteriohopanepolyols in marine suboxic and anoxic environments". Organic Geochemistry. 42 (11): 1351–1362. Bibcode:2011OrGeo..42.1351S. doi:10.1016/j.orggeochem.2011.08.016.
  21. 1 2 Summons RE, Jahnke LL, Hope JM, Logan GA (August 1999). "2-Methylhopanoids as biomarkers for cyanobacterial oxygenic photosynthesis". Nature. 400 (6744): 554–557. Bibcode:1999Natur.400..554S. doi:10.1038/23005. PMID   10448856.

See also

References

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