---
_id: '12781'
abstract:
- lang: eng
text: "Most energy in humans is produced in form of ATP by the mitochondrial respiratory
chain consisting of several protein assemblies embedded into lipid membrane (complexes
I-V). Complex I is the first and the largest enzyme of the respiratory chain which
is essential for energy production. It couples the transfer of two electrons from
NADH to ubiquinone with proton translocation across bacterial or inner mitochondrial
membrane. The coupling mechanism between electron transfer and proton translocation
is one of the biggest enigma in bioenergetics and structural biology. Even though
the enzyme has been studied for decades, only recent technological advances in
cryo-EM allowed its extensive structural investigation. \r\n\r\nComplex I from
E.coli appears to be of special importance because it is a perfect model system
with a rich mutant library, however the structure of the entire complex was unknown.
In this thesis I have resolved structures of the minimal complex I version from
E. coli in different states including reduced, inhibited, under reaction turnover
and several others. Extensive structural analyses of these structures and comparison
to structures from other species allowed to derive general features of conformational
dynamics and propose a universal coupling mechanism. The mechanism is straightforward,
robust and consistent with decades of experimental data available for complex
I from different species. \r\n\r\nCyanobacterial NDH (cyanobacterial complex I)
is a part of broad complex I superfamily and was studied as well in this thesis.
It plays an important role in cyclic electron transfer (CET), during which electrons
are cycled within PSI through ferredoxin and plastoquinone to generate proton
gradient without NADPH production. Here, I solved structure of NDH and revealed
additional state, which was not observed before. The novel “resting” state allowed
to propose the mechanism of CET regulation. Moreover, conformational dynamics
of NDH resembles one in complex I which suggest more broad universality of the
proposed coupling mechanism.\r\n\r\nIn summary, results presented here helped
to interpret decades of experimental data for complex I and contributed to fundamental
mechanistic understanding of protein function.\r\n"
acknowledged_ssus:
- _id: EM-Fac
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Vladyslav
full_name: Kravchuk, Vladyslav
id: 4D62F2A6-F248-11E8-B48F-1D18A9856A87
last_name: Kravchuk
citation:
ama: Kravchuk V. Structural and mechanistic study of bacterial complex I and its
cyanobacterial ortholog. 2023. doi:10.15479/at:ista:12781
apa: Kravchuk, V. (2023). Structural and mechanistic study of bacterial complex
I and its cyanobacterial ortholog. Institute of Science and Technology Austria.
https://doi.org/10.15479/at:ista:12781
chicago: Kravchuk, Vladyslav. “Structural and Mechanistic Study of Bacterial Complex
I and Its Cyanobacterial Ortholog.” Institute of Science and Technology Austria,
2023. https://doi.org/10.15479/at:ista:12781.
ieee: V. Kravchuk, “Structural and mechanistic study of bacterial complex I and
its cyanobacterial ortholog,” Institute of Science and Technology Austria, 2023.
ista: Kravchuk V. 2023. Structural and mechanistic study of bacterial complex I
and its cyanobacterial ortholog. Institute of Science and Technology Austria.
mla: Kravchuk, Vladyslav. Structural and Mechanistic Study of Bacterial Complex
I and Its Cyanobacterial Ortholog. Institute of Science and Technology Austria,
2023, doi:10.15479/at:ista:12781.
short: V. Kravchuk, Structural and Mechanistic Study of Bacterial Complex I and
Its Cyanobacterial Ortholog, Institute of Science and Technology Austria, 2023.
date_created: 2023-03-31T12:24:42Z
date_published: 2023-03-23T00:00:00Z
date_updated: 2023-08-04T08:54:51Z
day: '23'
ddc:
- '570'
- '572'
degree_awarded: PhD
department:
- _id: GradSch
- _id: LeSa
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ec_funded: 1
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relation: source_file
file_date_updated: 2023-04-20T07:02:59Z
has_accepted_license: '1'
language:
- iso: eng
month: '03'
oa_version: Published Version
page: '127'
project:
- _id: 238A0A5A-32DE-11EA-91FC-C7463DDC885E
grant_number: '25541'
name: 'Structural characterization of E. coli complex I: an important mechanistic
model'
- _id: 627abdeb-2b32-11ec-9570-ec31a97243d3
call_identifier: H2020
grant_number: '101020697'
name: Structure and mechanism of respiratory chain molecular machines
publication_identifier:
isbn:
- 978-3-99078-029-9
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '12138'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Leonid A
full_name: Sazanov, Leonid A
id: 338D39FE-F248-11E8-B48F-1D18A9856A87
last_name: Sazanov
orcid: 0000-0002-0977-7989
title: Structural and mechanistic study of bacterial complex I and its cyanobacterial
ortholog
type: dissertation
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
year: '2023'
...
---
_id: '8340'
abstract:
- lang: eng
text: Mitochondria are sites of oxidative phosphorylation in eukaryotic cells. Oxidative
phosphorylation operates by a chemiosmotic mechanism made possible by redox-driven
proton pumping machines which establish a proton motive force across the inner
mitochondrial membrane. This electrochemical proton gradient is used to drive
ATP synthesis, which powers the majority of cellular processes such as protein
synthesis, locomotion and signalling. In this thesis I investigate the structures
and molecular mechanisms of two inner mitochondrial proton pumping enzymes, respiratory
complex I and transhydrogenase. I present the first high-resolution structure
of the full transhydrogenase from any species, and a significantly improved structure
of complex I. Improving the resolution from 3.3 Å available previously to up to
2.3 Å in this thesis allowed us to model bound water molecules, crucial in the
proton pumping mechanism. For both enzymes, up to five cryo-EM datasets with different
substrates and inhibitors bound were solved to delineate the catalytic cycle and
understand the proton pumping mechanism. In transhydrogenase, the proton channel
is gated by reversible detachment of the NADP(H)-binding domain which opens the
proton channel to the opposite sites of the membrane. In complex I, the proton
channels are gated by reversible protonation of key glutamate and lysine residues
and breaking of the water wire connecting the proton pumps with the quinone reduction
site. The tight coupling between the redox and the proton pumping reactions in
transhydrogenase is achieved by controlling the NADP(H) exchange which can only
happen when the NADP(H)-binding domain interacts with the membrane domain. In
complex I, coupling is achieved by cycling of the whole complex between the closed
state, in which quinone can get reduced, and the open state, in which NADH can
induce quinol ejection from the binding pocket. On the basis of these results
I propose detailed mechanisms for catalytic cycles of transhydrogenase and complex
I that are consistent with a large amount of previous work. In both enzymes, conformational
and electrostatic mechanisms contribute to the overall catalytic process. Results
presented here could be used for better understanding of the human pathologies
arising from deficiencies of complex I or transhydrogenase and could be used to
develop novel therapies.
acknowledged_ssus:
- _id: EM-Fac
acknowledgement: 'I acknowledge the support of IST facilities, especially the Electron
Miscroscopy facility for providing training and resources. Special thanks also go
to cryo-EM specialists who helped me to collect the data present here: Dr Valentin
Hodirnau (IST Austria), Dr Tom Heuser (IMBA, Vienna), Dr Rebecca Thompson (Uni.
of Leeds) and Dr Jirka Nováček (CEITEC). This work has been supported by iNEXT,
project number 653706, funded by the Horizon 2020 programme of the European Union.
This project has received funding from the European Union’s Horizon 2020 research
and innovation programme under the Marie Skłodowska-Curie Grant Agreement No. 665385.'
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Domen
full_name: Kampjut, Domen
id: 37233050-F248-11E8-B48F-1D18A9856A87
last_name: Kampjut
citation:
ama: Kampjut D. Molecular mechanisms of mitochondrial redox-coupled proton pumping
enzymes. 2020. doi:10.15479/AT:ISTA:8340
apa: Kampjut, D. (2020). Molecular mechanisms of mitochondrial redox-coupled
proton pumping enzymes. Institute of Science and Technology Austria. https://doi.org/10.15479/AT:ISTA:8340
chicago: Kampjut, Domen. “Molecular Mechanisms of Mitochondrial Redox-Coupled Proton
Pumping Enzymes.” Institute of Science and Technology Austria, 2020. https://doi.org/10.15479/AT:ISTA:8340.
ieee: D. Kampjut, “Molecular mechanisms of mitochondrial redox-coupled proton pumping
enzymes,” Institute of Science and Technology Austria, 2020.
ista: Kampjut D. 2020. Molecular mechanisms of mitochondrial redox-coupled proton
pumping enzymes. Institute of Science and Technology Austria.
mla: Kampjut, Domen. Molecular Mechanisms of Mitochondrial Redox-Coupled Proton
Pumping Enzymes. Institute of Science and Technology Austria, 2020, doi:10.15479/AT:ISTA:8340.
short: D. Kampjut, Molecular Mechanisms of Mitochondrial Redox-Coupled Proton Pumping
Enzymes, Institute of Science and Technology Austria, 2020.
date_created: 2020-09-07T18:42:23Z
date_published: 2020-09-09T00:00:00Z
date_updated: 2023-09-07T13:26:17Z
day: '09'
ddc:
- '572'
degree_awarded: PhD
department:
- _id: LeSa
doi: 10.15479/AT:ISTA:8340
ec_funded: 1
file:
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checksum: dd270baf82121eb4472ad19d77bf227c
content_type: application/vnd.openxmlformats-officedocument.wordprocessingml.document
creator: dkampjut
date_created: 2020-09-08T13:32:06Z
date_updated: 2021-09-11T22:30:04Z
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file_name: ThesisFull20200908.docx
file_size: 166146359
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content_type: application/pdf
creator: dernst
date_created: 2020-09-14T15:02:20Z
date_updated: 2021-09-11T22:30:04Z
embargo: 2021-09-10
file_id: '8393'
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file_date_updated: 2021-09-11T22:30:04Z
has_accepted_license: '1'
language:
- iso: eng
month: '09'
oa: 1
oa_version: None
page: '242'
project:
- _id: 2564DBCA-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '665385'
name: International IST Doctoral Program
publication_identifier:
isbn:
- 978-3-99078-008-4
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '6848'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Leonid A
full_name: Sazanov, Leonid A
id: 338D39FE-F248-11E8-B48F-1D18A9856A87
last_name: Sazanov
orcid: 0000-0002-0977-7989
title: Molecular mechanisms of mitochondrial redox-coupled proton pumping enzymes
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2020'
...
---
_id: '8353'
abstract:
- lang: eng
text: "Mrp (Multi resistance and pH adaptation) are broadly distributed secondary
active antiporters that catalyze the transport of monovalent ions such as sodium
and potassium outside of the cell coupled to the inward translocation of protons.
Mrp antiporters are unique in a way that they are composed of seven subunits (MrpABCDEFG)
encoded in a single operon, whereas other antiporters catalyzing the same reaction
are mostly encoded by a single gene. Mrp exchangers are crucial for intracellular
pH homeostasis and Na+ efflux, essential mechanisms for H+ uptake under alkaline
environments and for reduction of the intracellular concentration of toxic cations.
Mrp displays no homology to any other monovalent Na+(K+)/H+ antiporters but Mrp
subunits have primary sequence similarity to essential redox-driven proton pumps,
such as respiratory complex I and membrane-bound hydrogenases. This similarity
reinforces the hypothesis that these present day redox-driven proton pumps are
descended from the Mrp antiporter. The Mrp structure serves as a model to understand
the yet obscure coupling mechanism between ion or electron transfer and proton
translocation in this large group of proteins. In the thesis, I am presenting
the purification, biochemical analysis, cryo-EM analysis and molecular structure
of the Mrp complex from Anoxybacillus flavithermus solved by cryo-EM at 3.0 Å
resolution. Numerous conditions were screened to purify Mrp to high homogeneity
and to obtain an appropriate distribution of single particles on cryo-EM grids
covered with a continuous layer of ultrathin carbon. A preferred particle orientation
problem was solved by performing a tilted data collection. The activity assays
showed the specific pH-dependent\r\nprofile of secondary active antiporters. The
molecular structure shows that Mrp is a dimer of seven-subunit protomers with
50 trans-membrane helices each. The dimer interface is built by many short and
tilted transmembrane helices, probably causing a thinning of the bacterial membrane.
The surface charge distribution shows an extraordinary asymmetry within each monomer,
revealing presumable proton and sodium translocation pathways. The two largest\r\nand
homologous Mrp subunits MrpA and MrpD probably translocate one proton each into
the cell. The sodium ion is likely being translocated in the opposite direction
within the small subunits along a ladder of charged and conserved residues. Based
on the structure, we propose a mechanism were the antiport activity is accomplished
via electrostatic interactions between the charged cations and key charged residues.
The flexible key TM helices coordinate these\r\nelectrostatic interactions, while
the membrane thinning between the monomers enables the translocation of sodium
across the charged membrane. The entire family of redox-driven proton pumps is
likely to perform their mechanism in a likewise manner."
acknowledged_ssus:
- _id: LifeSc
- _id: EM-Fac
- _id: ScienComp
acknowledgement: "I acknowledge the scientific service units of the IST Austria for
providing resources by the Life Science Facility, the Electron Microscopy Facility
and the high-performance computer cluster. Special thanks to the cryo-EM specialists
Valentin Hodirnau and Daniel Johann Gütl for spending many hours with me in front
of the microscope and for supporting me to collect the data presented here. I also
want to thank Professor Masahiro Ito for providing plasmid DNA\r\nencoding Mrp from
Anoxybacillus flavithermus WK1. I am a recipient of a DOC Fellowship of the Austrian
Academy of Sciences."
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Julia
full_name: Steiner, Julia
id: 3BB67EB0-F248-11E8-B48F-1D18A9856A87
last_name: Steiner
orcid: 0000-0003-0493-3775
citation:
ama: Steiner J. Biochemical and structural investigation of the Mrp antiporter,
an ancestor of complex I. 2020. doi:10.15479/AT:ISTA:8353
apa: Steiner, J. (2020). Biochemical and structural investigation of the Mrp
antiporter, an ancestor of complex I. Institute of Science and Technology
Austria. https://doi.org/10.15479/AT:ISTA:8353
chicago: Steiner, Julia. “Biochemical and Structural Investigation of the Mrp Antiporter,
an Ancestor of Complex I.” Institute of Science and Technology Austria, 2020.
https://doi.org/10.15479/AT:ISTA:8353.
ieee: J. Steiner, “Biochemical and structural investigation of the Mrp antiporter,
an ancestor of complex I,” Institute of Science and Technology Austria, 2020.
ista: Steiner J. 2020. Biochemical and structural investigation of the Mrp antiporter,
an ancestor of complex I. Institute of Science and Technology Austria.
mla: Steiner, Julia. Biochemical and Structural Investigation of the Mrp Antiporter,
an Ancestor of Complex I. Institute of Science and Technology Austria, 2020,
doi:10.15479/AT:ISTA:8353.
short: J. Steiner, Biochemical and Structural Investigation of the Mrp Antiporter,
an Ancestor of Complex I, Institute of Science and Technology Austria, 2020.
date_created: 2020-09-09T14:27:01Z
date_published: 2020-09-09T00:00:00Z
date_updated: 2023-09-07T13:14:09Z
day: '09'
ddc:
- '572'
degree_awarded: PhD
department:
- _id: LeSa
doi: 10.15479/AT:ISTA:8353
file:
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checksum: 2388d7e6e7a4d364c096fa89f305c3de
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language:
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month: '09'
oa: 1
oa_version: None
page: '191'
project:
- _id: 26169496-B435-11E9-9278-68D0E5697425
grant_number: '24741'
name: Revealing the functional mechanism of Mrp antiporter, an ancestor of complex
I
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '8284'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Leonid A
full_name: Sazanov, Leonid A
id: 338D39FE-F248-11E8-B48F-1D18A9856A87
last_name: Sazanov
orcid: 0000-0002-0977-7989
title: Biochemical and structural investigation of the Mrp antiporter, an ancestor
of complex I
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2020'
...