PREČO FAGOCYTÓZA NEMOHLA HRAŤ ÚLOHU PRI VZNIKU EUKARYOTOV

Marek Mentel 13. september 2018

Talk content

•  Phagocytosis and the origin of eukaryotes – historical considerations

•  Origin of eukaryotes theories – Mitochondria first vs. Phagocytosis first views

•  Phagocytosis in the context of host (archaeal) energy metabolism

•  Archaeal dynamic endomembrane system? – infering physiology from genetics

•  Endosymbionts within non-phagocytosing hosts

Phagocytosis – historical considerations

Phagocytosis – is the endocytic mechanism of large extracellular material internalization

using filopodial extensions, which is independent of clathrin

Phagocytosis – historical considerations

Phagocytosis – is the endocytic mechanism of large extracellular material internalization

using filopodial extensions, which is independent of clathrin

Etymology – German zoologist Carl Friedrich Wilhelm Claus (1835-1899; 1882): based

on Greek “phagein”=“to devour” and “kytos” =“cell”, suffix “-osis” =“process“

Pioneers – Canadian physician William Osler (1849-1919; 1876) and Russian zoologist

Ilya Ilyich Mechnikov (1845-1916; 1882), recognized as the discoverer

of phagocytosis

together with German physician Paul Ehrlich (1854-1915), was awarded

the Nobel Prize for Physiology or Medicine in 1908 “in recognition of their

work on immunity”

Phagocytosis and the origin of eukaryotes – historical considerations

Eukaryotes origin – autogenous or endosymbiotic

Cavalier-Smith, Nature 1975

plastids

mitochondria

Phagocytosis and the origin of eukaryotes – historical considerations

Eukaryotes origin – autogenous or endosymbiotic

Harish & Kurland, Biochimie 2017(!)

Phagocytosis and the origin of eukaryotes – historical considerations

Eukaryotes origin – autogenous or endosymbiotic

Mereschkowsky, 1905(!) – endosymbiotic origin of plastids invasion

Lynn Sagan (Margulis), 1967 – endosymbiotic origin of mitosing cells ingestion

De Duve, 1969 – endosymbiotic origin of peroxisomes phagotroph

Stanier, 1970 – endosymbiotic origin of plastids before mitochondria endocytosis

Phagocytosis and the origin of eukaryotes – historical considerations

Eukaryotes origin theories division - mitochondria early vs. mitochondria late

Pha

gocy

tosi

s fir

st M

itochondria first

Phagocytosis in the context of archaeal (host) energy metabolism

Phagotrophy - feeding habit; it entails the oxidation of ingested food particles for the

purpose of energy metabolism (ATP synthesis)

Organoheterotrophy - there are only two ways to harness energy as ATP by oxidizing

organic substrates: respiration and fermentation

Respiration – the process in which an organic compound is oxidized, usually

accompanied by ATP production by oxidative phosphorylation at the

expense of a proton motive force formed by electron transport chain

Fermentation – anaerobic catabolism in which an organic compound serves as both an

electron donor and an electron acceptor and ATP is produced/energy is

conserved via substrate-level phosphorylation (NOT exclusively)

Phagocytosis in the context of archaeal (host) energy metabolism – Respiration problem

if host was a Respirer – phagotrophy would mean that a section of the bioenergetic

membrane would be digested

– respiration chain complexes would have to be resynthesized

– protein synthesis is the most energetically expensive thing a

cell does, with 75% of the energy budget being devoted to

protein synthesis

Phagocytosis in the context of archaeal (host) energy metabolism - Fermentation

Phagotrophy - feeding habit; it entails the oxidation of ingested food particles for the

purpose of energy metabolism (ATP synthesis)

Organoheterotrophy - there are only two ways to harness energy as ATP by oxidizing

organic substrates: respiration and fermentation

Respiration – the process in which an organic compound is oxidized, usually

accompanied by ATP production by oxidative phosphorylation at the

expense of a proton motive force formed by electron transport chain

Fermentation – anaerobic catabolism in which an organic compound serves as both an

electron donor and an electron acceptor and ATP is produced/energy is

conserved via substrate-level phosphorylation (NOT exclusively)

Phagocytosis in the context of archaeal (host) energy metabolism – Fermentation with chemiosmotic coupling

Fermentation with chemiosmotic coupling – of succinate (Propionigenium modestum)

and oxalate (Oxalobacter formigenes)

Propionigenium modestum Oxalobacter formigenes

Phagocytosis in the context of archaeal (host) energy metabolism – Fermentation with chemiosmotic coupling

Fermentation with chemiosmotic coupling – typical also for archaeal amino acid and

carbohydrate fermentation

Contribution of chemiosmotic coupling to energy conservation in archaeal

fermentation is quantitatively significant

Pyrococcus furiosus carbohydrate fermentation – net balance of 3 ATP per glucose,

with equal contributions from SLP and chemiosmotic coupling

Phagocytosis in the context of archaeal (host) energy metabolism – Fermentation with chemiosmotic coupling

Fermentation with chemiosmotic coupling – typical also for archaeal amino acid and

carbohydrate fermentation

or

archaeal fermenter would need to sacrifice 40 to 50% of the ATP yield – the

chemiosmotic component – from amino acid or carbohydrate

fermentation in order to acquire substrates via engulfment

Archaeal phagocytosis? – what does it require?

Phagocytosis requires:

(1) functional, dynamic

endomembrane system

Archaeal phagocytosis? – is it plausible?

Dynamin – bacterium derived and likely of mitochondrial origin; absent from archaeal

genomes

Archaeal phagocytosis? – what does it require?

Phagocytosis requires: (2) hundreds of proteins to be functional

Phagocytosis requires: hundreds of proteins to be functional

Archaeal phagocytosis? – what does it require?

motor proteins – eukaryotic innovation

Archaeal phagocytosis? – what does it require?

V-ATPase – archaea derived (A-ATPase), but instead of synthesizing ATP from ADP

and Pi via chemiosmotic gradients V-ATPase pumps protons into the food

vacuole/lysosome to acidify it

Phagocytosis requires: hundreds of proteins to be functional

small GTPases – many with homology to the Ras superfamily – proteins of the Rab family mediate vesicles identity (address labels)

BUT – do not encode any membrane association signals or regions

essential for their function (prenylation) in Lokiarchaea

– lack of GTPase-activating proteins and exchange factors in Loki

Archaeal phagocytosis? – what does it require?

Cdv proteins – mediate the division of archaeal cells

Phagocytosis requires: hundreds of proteins to be functional

– homologous to components of eukaryotic ESCRT III (endosomal sorting

complex required for transport) complex

mediate membrane bending, budding and abscission

bending/budding away from

the cytoplasm !

scission of inward bending

in eukaryotes - dynamin

Endosymbionts within non-phagocytosing hosts Prokaryotes

cyanobacterium Pleurocapsa minor

with intracellular bacteria

bacterium Bdellovibrio bacteriovorus

within Pseudomonas fluorescens

Endosymbionts within non-phagocytosing hosts Eukaryotes

three bacteria within the matrix of a

mitochondrion (tick Ixodes ricinus)

endosymbiotic bacterium Sphingomonas

in mature mycelium of ascomycota

Stachylidium bicolor

Conclusion

A

Tu daj, že z dvoch dôvodov (energetický a cytologický) si myslíme, že mitochondria first je ten realistický scenár Prvý slide daj energetický dôvod Druhý slide daj cytologický dôvod Tretí slide daj príklady endosymbiontov v nefagocytujúcom hostiteľovi (aj v hubách)

Tu pokračuj s MMBR s. 19-23 a

V-ATPase s.19 – archaeálny pôvod ale orientácia a energetické požiadavky

Malé GTPázy mnohé homológia k Ras superrodiny s.21 – chýbajú GTPase activating proteins a GDP/GTP exchange faktory a tiež signál prenylácia

Cdv / ESCRT s. 22 aj s obrázkom – a ohýbanie in vs. out membrány

FtsZ a dedukcia fenotypu z prítomnosti génov s. 23

Dynamin s.16 obr. a s.22-23 - bakteriálny/mitochondriálny pôvod nie v Archaea