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Your search keyword '"Muijsers, A.O."' showing total 32 results
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32 results on '"Muijsers, A.O."'

2. R174 of Escherichia coli is involved in membrane-interaction and protofilament bundling, and is essential for cell division

Author

Koppelman, C.M., Aarsman, M.E.G., Postmus, J., Pas, E., Muijsers, A.O., Scheffers, D.-J., Nanninga, N., den Blaauwen, T., and Molecular Cytology (SILS, FNWI)

Subjects
bacteria, macromolecular substances, biological phenomena, cell phenomena, and immunity, physiological processes
Abstract

We investigated the interaction between FtsZ and the cytoplasmic membrane using inside-out vesicles. Comparison of the trypsin accessibility of purified FtsZ and cytoplasmic membrane-bound FtsZ revealed that the protruding loop between helix 6 and helix 7 is protected from trypsin digestion in the latter. This hydrophobic loop contains an arginine residue at position 174. To investigate the role of R174, this residue was replaced by an aspartic acid, and FtsZR174D was fused to green fluorescent protein (GFP). FtsZ-R174D-GFP could localize in an FtsZ and in an FtsZ84(Ts) background at both the permissive and the non-permissive temperature, and it had a reduced affinity for the cytoplasmic membrane compared with wild-type FtsZ. FtsZ-R174D could also localize in an FtsZ depletion strain. However, in contrast to wildtype FtsZ, FtsZ-R174D was not able to complement the ftsZ84 mutation or the depletion strain and induced filamentation. In vitro polymerization experiments showed that FtsZ-R174D is able to polymerize, but that these polymers cannot form bundles in the presence of 10 mM CaCl2. This is the first description of an FtsZ mutant that has reduced affinity for the cytoplasmic membrane and does not support cell division, but is still able to localize. The mutant is able to form protofilaments in vitro but fails to bundle. It suggests that neither membrane interaction nor bundling is a requirement for initiation of cell division.

Published
2004

6. A structure for the yeast prohibitin complex: Structure prediction and evidence from chemical crosslinking and mass spectrometry.

Author

Back, J.W., Sanz, M.A., Jong, M.C.J. de, Koning, L.J. de, Nijtmans, L.G.J., Koster, C.G. de, Grivell, L.A., Spek, H. van der, Muijsers, A.O., Back, J.W., Sanz, M.A., Jong, M.C.J. de, Koning, L.J. de, Nijtmans, L.G.J., Koster, C.G. de, Grivell, L.A., Spek, H. van der, and Muijsers, A.O.

Abstract

Item does not contain fulltext, The mitochondrial prohibitin complex consists of two subunits (PHB1 of 32 kD and PHB2 of 34 kD), assembled into a membrane-associated supercomplex of approximately 1 MD. A chaperone-like function in holding and assembling newly synthesized mitochondrial polypeptide chains has been proposed. To further elucidate the function of this complex, structural information is necessary. In this study we use chemical crosslinking, connecting lysine side chains, which are well scattered along the sequence. Crosslinked peptides from protease digested prohibitin complexes were identified with mass spectrometry. From these results, spatial restraints for possible protein conformation were obtained. Many interaction sites between PHB1 and PHB2 were found, whereas no homodimeric interactions were observed. Secondary and tertiary structural predictions were made using several algorithms and the models best fitting the spatial restraints were selected for further evaluation. From the structure predictions and the crosslink data we derived a structural building block of one PHB1 and one PHB2 subunit, strongly intertwined along most of their length. The size of the complex implies that approximately 14 of these building blocks are present. Each unit contains a putative transmembrane helix in PHB2. Taken together with the unit building block we postulate a circular palisade-like arrangement of the building blocks projecting into the intermembrane space.

Published
2002

7. Prohibitins act as a membrane-bound chaperone for the stabilization of mitochondrial proteins.

Author

Nijtmans, L.G.J., Jong, L.W.A.M. de, Sanz, M.A., Coates, P.J., Berden, J.A., Back, J.W., Muijsers, A.O., Spek, H. van der, Grivell, L.A., Nijtmans, L.G.J., Jong, L.W.A.M. de, Sanz, M.A., Coates, P.J., Berden, J.A., Back, J.W., Muijsers, A.O., Spek, H. van der, and Grivell, L.A.

Abstract

Item does not contain fulltext, Prohibitins are ubiquitous, abundant and evolutionarily strongly conserved proteins that play a role in important cellular processes. Using blue native electrophoresis we have demonstrated that human prohibitin and Bap37 together form a large complex in the mitochondrial inner membrane. This complex is similar in size to the yeast complex formed by the homologues Phb1p and Phb2p. In yeast, levels of this complex are increased on co-overexpression of both Phb1p and Phb2p, suggesting that these two proteins are the only components of the complex. Pulse-chase experiments with mitochondria isolated from phb1/phb2-null and PHB1/2 overexpressing cells show that the Phb1/2 complex is able to stabilize newly synthesized mitochondrial translation products. This stabilization probably occurs through a direct interaction because association of mitochondrial translation products with the Phb1/2 complex could be demonstrated. The fact that Phb1/2 is a large multimeric complex, which provides protection of native peptides against proteolysis, suggests a functional homology with protein chaperones with respect to their ability to hold and prevent misfolding of newly synthesized proteins.

Published
2000

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