Structure of the Ni/Fe-S Protein Subcomponent of the Acetyl-CoA Decarbonylase/Synthase Complex from Methanosarcina thermophila at 26-Å Resolution
| Autor: | Martin Kessel, Edward DeMoll, Eva Kocsis, David A. Grahame |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
Iron-Sulfur Proteins
biology ATP synthase Molecular mass Protein Conformation Chemistry Stereochemistry Archaeal Proteins Methanosarcina thermophila Size-exclusion chromatography biology.organism_classification Cleavage (embryo) Aldehyde Oxidoreductases law.invention Crystallography Multienzyme Complexes Structural Biology law Methanosarcina Scanning transmission electron microscopy Image Processing Computer-Assisted Microscopy Electron Scanning biology.protein Electron microscope Stoichiometry |
| Zdroj: | Journal of Structural Biology. 128:165-174 |
| ISSN: | 1047-8477 |
| Popis: | The acetyl-CoA decarbonylase/synthase (ACDS) complex is responsible for synthesis and cleavage of acetyl-CoA in methanogens. The complex is composed of five different subunits, with a probable stoichiometry of alpha(8)beta(8)gamma(8)delta(8)epsilon(8). The native molecular mass of a subcomponent of the ACDS complex from Methanosarcina thermophila, the Ni/Fe-S protein containing the 90-kDa alpha and 19-kDa epsilon subunits, was determined by scanning transmission electron microscopy. A value of 218.6 +/- 19.6 kDa (n = 566) was obtained, thus establishing that the oligomeric structure of this subcomponent is alpha(2)epsilon(2). The three-dimensional structure of alpha(2)epsilon(2) was determined at 26-A resolution by analysis of a large number of electron microscopic images of negatively stained, randomly oriented particles. The alpha(2)epsilon(2) subcomponent has a globular appearance, 110 A in diameter, and consists of two large, hemisphere-like masses that surround a hollow internal cavity. The two large masses are connected along one face by a bridge-like structure and have relatively less protein density joining them at other positions. The internal cavity has four main openings to the outside, one of which is directly adjacent to the bridge. The results are consistent with a structure in which the large hemispheric masses are assigned to the two alpha subunits, with epsilon(2) as the bridge forming a structural link between them. The structure of the alpha(2)epsilon(2) subcomponent is discussed in connection with biochemical data from gel filtration, crosslinking, and dissociation experiments and in the context of its function as a major component of the ACDS complex. |
| Databáze: | OpenAIRE |
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