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The Molecular Motor F-ATP Synthase Is Targeted by the Tumoricidal Protein HAMLET.

Ho, James; Sielaff, Hendrik; Nadeem, Aftab LU ; Svanborg, Catharina LU and Grüber, Gerhard (2015) In Journal of Molecular Biology 427(10). p.1866-1874
Abstract
HAMLET (human alpha-lactalbumin made lethal to tumor cells) interacts with multiple tumor cell compartments, affecting cell morphology, metabolism, proteasome function, chromatin structure and viability. This study investigated if these diverse effects of HAMLET might be caused, in part, by a direct effect on the ATP synthase and a resulting reduction in cellular ATP levels. A dose-dependent reduction in cellular ATP levels was detected in A549 lung carcinoma cells, and by confocal microscopy, co-localization of HAMLET with the nucleotide-binding subunits α (non-catalytic) and β (catalytic) of the energy converting F1F0 ATP synthase was detected. As shown by fluorescence correlation spectroscopy, HAMLET binds to the F1 domain of the F1F0... (More)
HAMLET (human alpha-lactalbumin made lethal to tumor cells) interacts with multiple tumor cell compartments, affecting cell morphology, metabolism, proteasome function, chromatin structure and viability. This study investigated if these diverse effects of HAMLET might be caused, in part, by a direct effect on the ATP synthase and a resulting reduction in cellular ATP levels. A dose-dependent reduction in cellular ATP levels was detected in A549 lung carcinoma cells, and by confocal microscopy, co-localization of HAMLET with the nucleotide-binding subunits α (non-catalytic) and β (catalytic) of the energy converting F1F0 ATP synthase was detected. As shown by fluorescence correlation spectroscopy, HAMLET binds to the F1 domain of the F1F0 ATP synthase with a dissociation constant (KD) of 20.5μM. Increasing concentrations of the tumoricidal protein HAMLET added to the enzymatically active α3β3γ complex of the F-ATP synthase lowered its ATPase activity, demonstrating that HAMLET binding to the F-ATP synthase effects the catalysis of this molecular motor. Single-molecule analysis was applied to study HAMLET-α3β3γ complex interaction. Whereas the α3β3γ complex of the F-ATP synthase rotated in a counterclockwise direction with a mean rotational rate of 3.8±0.7s(-1), no rotation could be observed in the presence of bound HAMLET. Our findings suggest that direct effects of HAMLET on the F-ATP synthase may inhibit ATP-dependent cellular processes. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Molecular Biology
volume
427
issue
10
pages
1866 - 1874
publisher
Elsevier
external identifiers
  • pmid:25681694
  • wos:000354145000002
  • scopus:84930651158
ISSN
1089-8638
DOI
10.1016/j.jmb.2015.01.024
language
English
LU publication?
yes
id
d5a339c2-a68c-4b3e-a0c9-5a5c90f51216 (old id 5143680)
alternative location
http://www.ncbi.nlm.nih.gov/pubmed/25681694?dopt=Abstract
date added to LUP
2015-03-07 16:51:45
date last changed
2017-09-17 04:22:36
@article{d5a339c2-a68c-4b3e-a0c9-5a5c90f51216,
  abstract     = {HAMLET (human alpha-lactalbumin made lethal to tumor cells) interacts with multiple tumor cell compartments, affecting cell morphology, metabolism, proteasome function, chromatin structure and viability. This study investigated if these diverse effects of HAMLET might be caused, in part, by a direct effect on the ATP synthase and a resulting reduction in cellular ATP levels. A dose-dependent reduction in cellular ATP levels was detected in A549 lung carcinoma cells, and by confocal microscopy, co-localization of HAMLET with the nucleotide-binding subunits α (non-catalytic) and β (catalytic) of the energy converting F1F0 ATP synthase was detected. As shown by fluorescence correlation spectroscopy, HAMLET binds to the F1 domain of the F1F0 ATP synthase with a dissociation constant (KD) of 20.5μM. Increasing concentrations of the tumoricidal protein HAMLET added to the enzymatically active α3β3γ complex of the F-ATP synthase lowered its ATPase activity, demonstrating that HAMLET binding to the F-ATP synthase effects the catalysis of this molecular motor. Single-molecule analysis was applied to study HAMLET-α3β3γ complex interaction. Whereas the α3β3γ complex of the F-ATP synthase rotated in a counterclockwise direction with a mean rotational rate of 3.8±0.7s(-1), no rotation could be observed in the presence of bound HAMLET. Our findings suggest that direct effects of HAMLET on the F-ATP synthase may inhibit ATP-dependent cellular processes.},
  author       = {Ho, James and Sielaff, Hendrik and Nadeem, Aftab and Svanborg, Catharina and Grüber, Gerhard},
  issn         = {1089-8638},
  language     = {eng},
  number       = {10},
  pages        = {1866--1874},
  publisher    = {Elsevier},
  series       = {Journal of Molecular Biology},
  title        = {The Molecular Motor F-ATP Synthase Is Targeted by the Tumoricidal Protein HAMLET.},
  url          = {http://dx.doi.org/10.1016/j.jmb.2015.01.024},
  volume       = {427},
  year         = {2015},
}