Life at Extreme Temperatures

SYMPOZJUM DOKTORANCKIE

Life at extreme temperatures

Bartosz Różycki IF PAN Warsaw, November 3, 2016 Temperatures on Earth 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) Life at extreme temperatures

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L.J. Rothschild & R.L. Mancinelli, Nature 409, 2001 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 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 Liquid water on Earth 500

deep-see hydrothermal vents 400

] 300 C ° [ e r u

t 200 a r e p 100 m e T 0 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 What are the limits of temperature for life on Earth? 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 Properties of life

1. Homeostasis (regulation of the internal environment to maintain a constant state)

2. Organization (entities composed of one or more biological cells)

3. Metabolism

4. Growth

5. Reproduction

6. Response to stimuli

7. Adaptation (through natural selection) to environment in successive generations 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 • The deepest rooted organisms are thermophiles Life at extreme temperatures

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s fungi e t o

y protozoa r a k

u plants E animals

L.J. Rothschild & R.L. Mancinelli, Nature 409, 2001 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 (micro- animals) can survive a few days at -200 °C 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 Are they loving or just tolerant? e s a

b Mesophilic organisms10 °C < T < 45 °C a t Example: plant pathogens – a Extremeotolerant organisms D

bacteria – found in the t c

e Extremeophilic organisms stratosphere j o r Ø

P cryophiles live at T < -2 °C e Ø m psychrophiles grow optimally at T < 10 °C o n e Ø thermophiles thrive at T > 45 °C G l

a Ø i hyperthermophile live at T > 75 °C b o r c i

M 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… Living organisms are sensitive to temperature changes

extremeophilic microorganisms Click to edit Master text styles Second level Third level Fourth level

e Fifth level t a r h t w o r G

Temperature (°C) 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 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) How have the living organisms adapted to extreme temperatures? Molecules of life s s a m

r a l u c e l o m

Molecular Biology of the Cell (© Garland Science 2008) Water

NASA Polarity

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

Polar molecules, such as H2O, have a permanent dipole moment molecule [D] H2O 1,85 HCl 1,08 CO 0,117 O2 1D=3,335640  10-30 C  m

Molecular Biology of the Cell (© Garland Science 2008) Are they scared of water?

C-C and C-H bonds are non-polar Example: hydrocarbons

Oils consists of hydrocarbons

hydrophobic Hydrogen bonds

Molecular Biology of the Cell (© Garland Science 2008) Hydrophilic

polar molecules ions

hydrogen bonds electrostatic interactions

Molecular Biology of the Cell (© Garland Science 2008) Hydrophobic

• Water molecules do not form hydration layers around such molecules

Molecular Biology of the Cell (© Garland Science 2008) Hydrophobic effect

Hydrophobic molecules tend to contact one another…

… because of the entropy of water

Molecular Biology of the Cell (© Garland Science 2008) BioMacroMolecules

Lipids Nucleic acids (RNA & DNA) Proteins BioMacroMolecules

Lipids Nucleic acids (RNA & DNA) Proteins Lipids: it is a matter of heads and tails

lipids are amphipathic molecules

lipid bilayer d i p i l o h p s o h p 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) Lipid membranes of psychrophiles

Challenge: sustain membrane fluidity at low temperatures (fluid-gel transition) 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 • increased Fifth level (poly)unsaturate d to saturated lipid ratios • shorter tails

Unsaturated lipids Lipid membranes of thermophiles

Challenge: prevent membrane damage at high temperatures

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Lipids Nucleic acids (RNA & DNA) Proteins Nucleic acids

Molecular Biology of the Cell (© Garland Science 2008) Nucleic acids: everyone pair up! e d i t o e l c u n y l o p Base pairs DNA melting - things are unraveling fast

T < Tm

T > Tm 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 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) DNA melting - with a pinch of salt ) C ° (

T < Tm m T

e r u t a

T > Tm r e p m e t

Tm depends on the fraction g n i t l

of the G:C pairs in the DNA e

molecule, and also on the m G:C fraction salt concentration in the (Biochemistry 43, 3537-3554, 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 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 BioMacroMolecules

Lipids Nucleic acids (RNA & DNA) Proteins Amino acids amino carboxyl group group

loops

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 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 Thermal stability and activity of enzymes c c i c i l i l i l i i h h h p p p o o r o h s m c r e y e m s h t p

Georges Feller 2010 J. Phys.: Condens. Matter 22, 323101 Some proteins are common to (almost) all organisms Example: - Bacterium 31 °C Arthrobacter citrate strain DS2- 3R synthase - Pig 37 °C

- archaeon Thermoplasm 55 °C a acidophilum - archaeon Sulfolobus 83 °C solfataricus - archaeon

PyrococcusBell, Russell, et al., European100 Journal °C of Biochemistry 269, 6250-6260, furiosus2002 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 organisms 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 organisms “adaptive proteins” have specific functions that allow cells to adapt to its surrounding environment. Examples: antifreeze proteins. Enzymes from thermophiles – applications Example: polymerase chain reaction

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Kary B. Mullis: 1993 Nobel Prize in Chemistry Enzymes from thermophiles – applications Example: biofuel production

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Life at extreme temperatures

Bartosz Różycki IF PAN November 3, 2016 Temperatures on Earth

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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.