TY - JOUR
T1 - Stress-dependent macromolecular crowding in the mitochondrial matrix
AU - Bulthuis, Elianne P.
AU - Dieteren, Cindy E.J.
AU - Bergmans, Jesper
AU - Berkhout, Job
AU - Wagenaars, Jori A.
AU - van de Westerlo, Els M.A.
AU - Podhumljak, Emina
AU - Hink, Mark A.
AU - Hesp, Laura F.B.
AU - Rosa, Hannah S.
AU - Malik, Afshan N.
AU - Lindert, Mariska Kea te
AU - Willems, Peter H.G.M.
AU - Gardeniers, Han J.G.E.
AU - den Otter, Wouter K.
AU - Adjobo-Hermans, Merel J.W.
AU - Koopman, Werner J.H.
N1 - Publisher Copyright:
© 2023 The Authors. Published under the terms of the CC BY NC ND 4.0 license.
PY - 2023/2/24
Y1 - 2023/2/24
N2 - Macromolecules of various sizes induce crowding of the cellular environment. This crowding impacts on biochemical reactions by increasing solvent viscosity, decreasing the water-accessible volume and altering protein shape, function, and interactions. Although mitochondria represent highly protein-rich organelles, most of these proteins are somehow immobilized. Therefore, whether the mitochondrial matrix solvent exhibits macromolecular crowding is still unclear. Here, we demonstrate that fluorescent protein fusion peptides (AcGFP1 concatemers) in the mitochondrial matrix of HeLa cells display an elongated molecular structure and that their diffusion constant decreases with increasing molecular weight in a manner typical of macromolecular crowding. Chloramphenicol (CAP) treatment impaired mitochondrial function and reduced the number of cristae without triggering mitochondrial orthodox-to-condensed transition or a mitochondrial unfolded protein response. CAP-treated cells displayed progressive concatemer immobilization with increasing molecular weight and an eightfold matrix viscosity increase, compatible with increased macromolecular crowding. These results establish that the matrix solvent exhibits macromolecular crowding in functional and dysfunctional mitochondria. Therefore, changes in matrix crowding likely affect matrix biochemical reactions in a manner depending on the molecular weight of the involved crowders and reactants.
AB - Macromolecules of various sizes induce crowding of the cellular environment. This crowding impacts on biochemical reactions by increasing solvent viscosity, decreasing the water-accessible volume and altering protein shape, function, and interactions. Although mitochondria represent highly protein-rich organelles, most of these proteins are somehow immobilized. Therefore, whether the mitochondrial matrix solvent exhibits macromolecular crowding is still unclear. Here, we demonstrate that fluorescent protein fusion peptides (AcGFP1 concatemers) in the mitochondrial matrix of HeLa cells display an elongated molecular structure and that their diffusion constant decreases with increasing molecular weight in a manner typical of macromolecular crowding. Chloramphenicol (CAP) treatment impaired mitochondrial function and reduced the number of cristae without triggering mitochondrial orthodox-to-condensed transition or a mitochondrial unfolded protein response. CAP-treated cells displayed progressive concatemer immobilization with increasing molecular weight and an eightfold matrix viscosity increase, compatible with increased macromolecular crowding. These results establish that the matrix solvent exhibits macromolecular crowding in functional and dysfunctional mitochondria. Therefore, changes in matrix crowding likely affect matrix biochemical reactions in a manner depending on the molecular weight of the involved crowders and reactants.
KW - chloramphenicol
KW - diffusion
KW - FRAP
KW - macromolecular crowding
KW - mitochondria
UR - http://www.scopus.com/inward/record.url?scp=85148598028&partnerID=8YFLogxK
U2 - 10.15252/embj.2021108533
DO - 10.15252/embj.2021108533
M3 - Article
C2 - 36825437
AN - SCOPUS:85148598028
SN - 0261-4189
VL - 42
JO - EMBO journal
JF - EMBO journal
IS - 7
M1 - e108533
ER -