Catalytic activities of mitochondrial ATP synthase in patients with mitochondrial DNA T8993G mutation in the ATPase 6 gene encoding subunit a

Alessandra Baracca, Silvia Barogi, Valerio Carelli, Giorgio Lenaz, Giancarlo Solaini

Research output: Contribution to journalArticle

86 Citations (Scopus)

Abstract

We investigated the biochemical phenotype of the mtDNA T8993G point mutation in the ATPase 6 gene, associated with neurogenic muscle weakness, ataxia, and retinitis pigmentosa (NARP), in three patients from two unrelated families. All three carried >80% mutant genome in platelets and were manifesting clinically various degrees of the NARP phenotype. Coupled submitochondrial particles prepared from platelets capable of succinate- sustained ATP synthesis were studied using very sensitive and rapid luminometric and fluorescence methods. A sharp decrease (>95%) in the succinate-sustained ATP synthesis rate of the particles was found, but both the ATP hydrolysis rate and ATP-driven proton translocation (when the protons flow from the matrix to the cytosol) were minimally affected. The T8993G mutation changes the highly conserved residue Leu156 to Arg in the ATPase 6 subunit (subunit a). This subunit, together with subunit c, is thought to cooperatively catalyze proton translocation and rotate, one with respect to the other, during the catalytic cycle of the F1F0 complex. Our results suggest that the T8993G mutation induces a structural defect in human F1F0- ATPase that causes a severe impairment of ATP synthesis. This is possibly due to a defect in either the vectorial proton transport from the cytosol to the mitochondrial matrix or the coupling of proton flow through F0 to ATP synthesis in F1. Whatever mechanism is involved, this leads to impaired ATP synthesis. On the other hand, ATP hydrolysis that involves proton flow from the matrix to the cytosol is essentially unaffected.

Original languageEnglish
Pages (from-to)4177-4182
Number of pages6
JournalJournal of Biological Chemistry
Volume275
Issue number6
DOIs
Publication statusPublished - Feb 11 2000

Fingerprint

Mitochondrial Proton-Translocating ATPases
Gene encoding
Mitochondrial DNA
Adenosine Triphosphatases
Catalyst activity
Adenosine Triphosphate
Protons
Mutation
Genes
Cytosol
Succinic Acid
Platelets
Muscle
Hydrolysis
Blood Platelets
Submitochondrial Particles
Phenotype
Defects
Point Mutation
Fluorescence

ASJC Scopus subject areas

  • Biochemistry

Cite this

Catalytic activities of mitochondrial ATP synthase in patients with mitochondrial DNA T8993G mutation in the ATPase 6 gene encoding subunit a. / Baracca, Alessandra; Barogi, Silvia; Carelli, Valerio; Lenaz, Giorgio; Solaini, Giancarlo.

In: Journal of Biological Chemistry, Vol. 275, No. 6, 11.02.2000, p. 4177-4182.

Research output: Contribution to journalArticle

@article{cb243328c6774635ab4dc841ae589e26,
title = "Catalytic activities of mitochondrial ATP synthase in patients with mitochondrial DNA T8993G mutation in the ATPase 6 gene encoding subunit a",
abstract = "We investigated the biochemical phenotype of the mtDNA T8993G point mutation in the ATPase 6 gene, associated with neurogenic muscle weakness, ataxia, and retinitis pigmentosa (NARP), in three patients from two unrelated families. All three carried >80{\%} mutant genome in platelets and were manifesting clinically various degrees of the NARP phenotype. Coupled submitochondrial particles prepared from platelets capable of succinate- sustained ATP synthesis were studied using very sensitive and rapid luminometric and fluorescence methods. A sharp decrease (>95{\%}) in the succinate-sustained ATP synthesis rate of the particles was found, but both the ATP hydrolysis rate and ATP-driven proton translocation (when the protons flow from the matrix to the cytosol) were minimally affected. The T8993G mutation changes the highly conserved residue Leu156 to Arg in the ATPase 6 subunit (subunit a). This subunit, together with subunit c, is thought to cooperatively catalyze proton translocation and rotate, one with respect to the other, during the catalytic cycle of the F1F0 complex. Our results suggest that the T8993G mutation induces a structural defect in human F1F0- ATPase that causes a severe impairment of ATP synthesis. This is possibly due to a defect in either the vectorial proton transport from the cytosol to the mitochondrial matrix or the coupling of proton flow through F0 to ATP synthesis in F1. Whatever mechanism is involved, this leads to impaired ATP synthesis. On the other hand, ATP hydrolysis that involves proton flow from the matrix to the cytosol is essentially unaffected.",
author = "Alessandra Baracca and Silvia Barogi and Valerio Carelli and Giorgio Lenaz and Giancarlo Solaini",
year = "2000",
month = "2",
day = "11",
doi = "10.1074/jbc.275.6.4177",
language = "English",
volume = "275",
pages = "4177--4182",
journal = "Journal of Biological Chemistry",
issn = "0021-9258",
publisher = "American Society for Biochemistry and Molecular Biology Inc.",
number = "6",

}

TY - JOUR

T1 - Catalytic activities of mitochondrial ATP synthase in patients with mitochondrial DNA T8993G mutation in the ATPase 6 gene encoding subunit a

AU - Baracca, Alessandra

AU - Barogi, Silvia

AU - Carelli, Valerio

AU - Lenaz, Giorgio

AU - Solaini, Giancarlo

PY - 2000/2/11

Y1 - 2000/2/11

N2 - We investigated the biochemical phenotype of the mtDNA T8993G point mutation in the ATPase 6 gene, associated with neurogenic muscle weakness, ataxia, and retinitis pigmentosa (NARP), in three patients from two unrelated families. All three carried >80% mutant genome in platelets and were manifesting clinically various degrees of the NARP phenotype. Coupled submitochondrial particles prepared from platelets capable of succinate- sustained ATP synthesis were studied using very sensitive and rapid luminometric and fluorescence methods. A sharp decrease (>95%) in the succinate-sustained ATP synthesis rate of the particles was found, but both the ATP hydrolysis rate and ATP-driven proton translocation (when the protons flow from the matrix to the cytosol) were minimally affected. The T8993G mutation changes the highly conserved residue Leu156 to Arg in the ATPase 6 subunit (subunit a). This subunit, together with subunit c, is thought to cooperatively catalyze proton translocation and rotate, one with respect to the other, during the catalytic cycle of the F1F0 complex. Our results suggest that the T8993G mutation induces a structural defect in human F1F0- ATPase that causes a severe impairment of ATP synthesis. This is possibly due to a defect in either the vectorial proton transport from the cytosol to the mitochondrial matrix or the coupling of proton flow through F0 to ATP synthesis in F1. Whatever mechanism is involved, this leads to impaired ATP synthesis. On the other hand, ATP hydrolysis that involves proton flow from the matrix to the cytosol is essentially unaffected.

AB - We investigated the biochemical phenotype of the mtDNA T8993G point mutation in the ATPase 6 gene, associated with neurogenic muscle weakness, ataxia, and retinitis pigmentosa (NARP), in three patients from two unrelated families. All three carried >80% mutant genome in platelets and were manifesting clinically various degrees of the NARP phenotype. Coupled submitochondrial particles prepared from platelets capable of succinate- sustained ATP synthesis were studied using very sensitive and rapid luminometric and fluorescence methods. A sharp decrease (>95%) in the succinate-sustained ATP synthesis rate of the particles was found, but both the ATP hydrolysis rate and ATP-driven proton translocation (when the protons flow from the matrix to the cytosol) were minimally affected. The T8993G mutation changes the highly conserved residue Leu156 to Arg in the ATPase 6 subunit (subunit a). This subunit, together with subunit c, is thought to cooperatively catalyze proton translocation and rotate, one with respect to the other, during the catalytic cycle of the F1F0 complex. Our results suggest that the T8993G mutation induces a structural defect in human F1F0- ATPase that causes a severe impairment of ATP synthesis. This is possibly due to a defect in either the vectorial proton transport from the cytosol to the mitochondrial matrix or the coupling of proton flow through F0 to ATP synthesis in F1. Whatever mechanism is involved, this leads to impaired ATP synthesis. On the other hand, ATP hydrolysis that involves proton flow from the matrix to the cytosol is essentially unaffected.

UR - http://www.scopus.com/inward/record.url?scp=0034635388&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0034635388&partnerID=8YFLogxK

U2 - 10.1074/jbc.275.6.4177

DO - 10.1074/jbc.275.6.4177

M3 - Article

VL - 275

SP - 4177

EP - 4182

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 6

ER -