Life at extreme temperatures

Transcription

1 SYMPOZJUM DOKTORANCKIE Life at extreme temperatures Bartosz Różycki IF PAN Warsaw, November 3, 2016

2 Temperatures on Earth

3 Extreme temperatures on Earth World Meteorological Organization the lowest and highest air temperature ever directly recorded at ground level on Earth: 89.2 C (Vostok Station in Antarctica, July 1983) 56.7 C (Death Valley, USA, July 1913) - geothermally heated water: hot springs (up to 100 C), deep-see hydrothermal vents (up to ~400 C)

4 Life at extreme temperatures Click to edit Master text styles Second level Third level Fourth level Fifth level L.J. Rothschild & R.L. Mancinelli, Nature 409, 2001

5 Life at extreme temperatures thermophiles some like it hot Click to edit Master text styles Second level Third level Fourth level Fifth level L.J. Rothschild & R.L. Mancinelli, Nature 409, 2001

6 Life at extreme temperatures psychrophiles/cryophiles some like it cold Click to edit Master text styles Second level Third level Fourth level Fifth level (Himalayan midge) Nature 310, 1984

7 Liquid water on Earth 500 deep-see hydrothermal vents Temperature [ C] Antarctic salt lakes Don Juan Pond (Antarctica) does not freeze at -50 C 413 g of CaCl2 and 29 g of NaCl per kg of water

8 What are the limits of temperature for life on Earth?

9 What are the limits of temperature for life on Earth? definition of life Merriam-Webster: Living organisms have the capacity for metabolism, growth, reaction to stimuli, and reproduction

10 Properties of life Homeostasis (regulation of the internal environment to maintain a constant state) Organization (entities composed of one or more biological cells) Metabolism Growth Reproduction Response to stimuli Adaptation (through natural selection) to environment in successive generations

11 Click to edit Master text styles Second level Third level Fourth level Fifth level (we live on a microbial planet) Woese et al., PNAS, 1990 The three domains of life have arose from a common ancestor Bacteria and Archaea are prokaryotic organisms Eukaryotic organisms evolved from Archaea The cyanobacteria (ancestors of all oxygen-producing photosynthetic organisms) are not deeply rooted

12 Life at extreme temperatures Eukaryotes Click to edit Master text styles Second level Third level Fourth level Fifth level archaea bacteria algae fungi protozoa plants animals L.J. Rothschild & R.L. Mancinelli, Nature 409, 2001

13 What are the limits of temperature for life on Earth? Himalayan midge (insect) remains active at -16 C Yeast Rhodotorula glutinis can cause frozen food spoilage at -18 C Planococcus halocryophilus, a gram-positive bacteria, isolated from high Arctic permafrost, grows and divides at -15 C and is metabolically active at -25 C Water bears / moss piglets (microanimals) can survive a few days at -200 C

14 What are the limits of temperature for life on Earth? Strain 121 (Geogemma barossii, Archaea), found near a hydrothermal vent, is able to grow and reproduce at 121 C, the highest temperature demonstrated to date (Science 2003) 130 C is the biostatic for Strain 121: although growth is halted, the archaeum remains viable, and can resume reproducing once it has been transferred to a cooler medium

15 Microbial Genome Project Database Are they loving or just tolerant? Mesophilic organisms10 C < T < 45 C plant pathogens Extremeotolerant organisms Example: bacteria found in the Extremeophilic organisms stratosphere Ø cryophiles live at T < -2 C Ø psychrophiles grow optimally at T < 10 C Ø thermophiles thrive at T > 45 C Ø hyperthermophile live at T > 75 C found in various geothermally heated regions such as hot springs and deep-see hydrothermal vents as well as decaying plant matter (compost) found in oceans (which cover 70% of the Earth s surface), polar regions, mountains

16 Living organisms are sensitive to temperature changes Growth rate extremeophilic microorganisms Click to edit Master text styles Second level Third level Fourth level Fifth level Temperature ( C)

17 Negative effects of high temperature Examples: low solubility of O2 and CO2 in water (example: no fish found at T > 40 C) degradation of chlorophyll at T > 75 C (meaning no photosynthesis) denaturation of proteins and nucleic acids increased fluidity or damage of cellular membranes

18 Negative effects of low temperature Examples: increased viscosity of fluids; slower diffusion; smaller mobility of nutrients and wastes formation of ice crystals enzyme kinetics decreased fluidity of cellular membranes (liquid-gel transition of lipid membranes)

19 How have the living organisms adapted to extreme temperatures?

20 molecular mass Molecules of life Molecular Biology of the Cell ( Garland Science 2008)

21 Water NASA

22 Polarity Molecular Biology of the Cell ( Garland Science 2008)

23 Polarity Polar molecules, such as H2O, have a permanent dipole moment molecule [D] H2O 1,85 HCl 1,08 CO 0,117 O2 0 1D=3, C m Molecular Biology of the Cell ( Garland Science 2008)

24 Are they scared of water? C-C and C-H bonds are non-polar Example: hydrocarbons Oils consists of hydrocarbons hydrophobic

25 Hydrogen bonds Molecular Biology of the Cell ( Garland Science 2008)

26 Hydrophilic polar molecules hydrogen bonds Molecular Biology of the Cell ( Garland Science 2008) ions electrostatic interactions

27 Hydrophobic Water molecules do not form hydration layers around such molecules Molecular Biology of the Cell ( Garland Science 2008)

28 Hydrophobic effect Hydrophobic molecules tend to contact one another because of the entropy of water Molecular Biology of the Cell ( Garland Science 2008)

29 BioMacroMolecules Lipids Nucleic acids (RNA & DNA) Proteins

30 BioMacroMolecules Lipids Nucleic acids (RNA & DNA) Proteins

31 Lipids: it is a matter of heads and tails lipids are amphipathic molecules phospholipid lipid bilayer

32 Lipid bilayers & cellular membranes The plasma membrane is a boundary between the interior of a living cell and its environment. It regulates the transfer of materials and information in and out of the cell. Molecular Biology of the Cell ( Garland Science 2008)

33 Lipid membranes of psychrophiles Challenge: sustain membrane fluidity at low temperatures (fluid-gel transition)

34 Lipid membranes of psychrophiles Challenge: sustain membrane fluidity at low temperatures (fluid-gel transition) Click to edit Master text styles reduced size of Second level Third level the head groups Fourth level Fifth level increased (poly)unsaturate d to saturated lipid ratios shorter tails Unsaturated lipids

35 Lipid membranes of thermophiles Challenge: prevent membrane damage at high temperatures Click to edit Master text styles Second level Third level Fourth level Fifth level

36 BioMacroMolecules Lipids Nucleic acids (RNA & DNA) Proteins

37 Nucleic acids Molecular Biology of the Cell ( Garland Science 2008)

38 polynucleotide Nucleic acids: everyone pair up!

39 Base pairs

40 DNA melting - things are unraveling fast T < Tm T > Tm

41 DNA melting - three are better than two Tm depends on the fraction of the G:C base pairs, which have 3 hydrogen bonds T < Tm T > Tm increased G:C fractions are found in the DNA of prokaryotic thermophiles

42 Genetic code The central dogma of molecular biology DNA 3 base pairs codon one amino acid transcription (polymerase) RNA translation (ribosome) proteins DNA codon table (Wikipedia)

43 T < Tm T > Tm melting temperature Tm ( C) DNA melting - with a pinch of salt Tm depends on the fraction of the G:C pairs in the DNA molecule, and also on the G:C fraction salt concentration in the (Biochemistry 43, , 2004) solution Salts enhance the stability of nucleic acids because they screen the negative charges of the phosphate groups KCl, MgCl2 are found at higher levels in thermophilic archaea

44 Protein machineries prevent DNA melting Reverse DNA gyrases induce positive supercoiling of DNA, which raises Tm. These proteins appear to be unique to hyperthermophiles. Their function is to protect the genome from denaturation. Wikipedia Biochemical Society Transactions 31, 58-63, 2011

45 BioMacroMolecules Lipids Nucleic acids (RNA & DNA) Proteins

46 Amino acids Molecular Biology of the Cell ( Garland Science 2008) amino group carboxyl group

47 polypeptides

48 Protein secondary structure: amino acid sequence Molecular Biology of the Cell ( Garland Science 2008)

49 Secondary structure: α helices Molecular Biology of the Cell ( Garland Science 2008)

50 Secondary structure: β sheets Molecular Biology of the Cell ( Garland Science 2008)

51 Ternary structure loops Molecular Biology of the Cell ( Garland Science 2008)

52 structure-function relations The majority of proteins perform their biological functions (catalysis, transcription & translation, signaling ) only when folded into appropriate structures (native structures) Proteins usually exhibit structural rearrangements when performing their function

53 Temperature affects protein structures and motions high temperatures: proteins unfold, i.e. lose their structures low temperatures: protein motions are hindered - There is a certain temperature window at which a given protein can function - Chemical and structural properties of proteins must be adapted to the temperature at which the organism thrives

54 thermophilic mesophilic psychrophilic Thermal stability and activity of enzymes Georges Feller 2010 J. Phys.: Condens. Matter 22,

55 Some proteins are common to (almost) all organisms Example: citrate synthase - Bacterium Arthrobacter strain DS23R 31 C - Pig 37 C - archaeon Thermoplasm 55 C a acidophilum - archaeon Sulfolobus solfataricus 83 C - archaeon Pyrococcus 100 C Bell, Russell, et al., European Journal of Biochemistry 269, ,

56 Psychrophiles tend to contain proteins with: longer loops: reduced content of prolines (more flexible backbone); predominance of neutral amino-acid residues less hydrophobic and less compact cores larger cavities higher proportions of surface-exposed non-polar residues increased lysine-to-arginine rations (weaker hydrogen bonds and salt bridges) increased asparagine, methionine and glycine contents compared to proteins in mesophilic

57 Thermophiles tend to contain proteins with: shorter loops and smaller cavities more compact & hydrophobic protein core larger numbers of ionic bonds increased polarity of water-exposed surfaces increased arginine-to-lysine contents increased contents of charged residues and tryptophan smaller contents of asparagine and methionine compared to proteins in mesophilic

58 adaptive proteins have specific functions that allow cells to adapt to its surrounding environment. Examples: antifreeze proteins.

59 Enzymes from thermophiles applications Example: polymerase chain reaction Click to edit Master text styles Second level Third level Fourth level Fifth level Kary B. Mullis: 1993 Nobel Prize in Chemistry

60 Enzymes from thermophiles applications Example: biofuel production Click to edit Master text styles Second level Third level Fourth level Fifth level cellulosomes

61 SYMPOZJUM DOKTORANCKIE Life at extreme temperatures Bartosz Różycki IF PAN November 3, 2016

62 Temperatures on Earth Click to edit Master text styles Second level Third level Fourth level Fifth level Temperature of the Earth s surface or clouds (April 2003). The scale ranges from -81 C (192 K) to 47 C (320 K). The Atmospheric Infrared Sounder (AIRS) instrument aboard NASA s Aqua satellite senses temperature using infrared wavelengths.