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Chemical Reviews Apr 2014
Review
Topics: Acetate-CoA Ligase; Aldehyde Oxidoreductases; Animals; Humans; Metalloproteins; Multienzyme Complexes; Nickel
PubMed: 24521136
DOI: 10.1021/cr400461p -
FEBS Letters Aug 1990There are continuing reports on the existence of complexes of sequential metabolic enzymes. New techniques for their detection have been described and include affinity... (Review)
Review
There are continuing reports on the existence of complexes of sequential metabolic enzymes. New techniques for their detection have been described and include affinity electrophoresis and the use of anti-idiotypic antibodies. Channeling of substrates has been reported for several systems as well as direct substrate transfer through dynamic enzyme associations. Kinetic parameters of metabolic control of organized systems have been formulated and tested in several systems. These recent results are expanding our understanding of metabolic processes and their control.
Topics: Biological Transport; Glycolysis; Kinetics; Multienzyme Complexes
PubMed: 2200717
DOI: 10.1016/0014-5793(90)81286-w -
Current Biology : CB Sep 1996Newly synthesized proteins that fail to fold or assemble properly in the endoplasmic reticulum are degraded. Recent work on several endoplasmic reticulum membrane... (Review)
Review
Newly synthesized proteins that fail to fold or assemble properly in the endoplasmic reticulum are degraded. Recent work on several endoplasmic reticulum membrane proteins has shown that the cytosolic proteasome plays a role in their degradation.
Topics: Cysteine Endopeptidases; Endoplasmic Reticulum; Hydrolysis; Membrane Proteins; Multienzyme Complexes; Proteasome Endopeptidase Complex; Protein Folding
PubMed: 8805359
DOI: 10.1016/s0960-9822(02)70666-0 -
Molecular Cell Jul 2006As the replication fork progresses, synthesis of the discontinuous lagging strand requires frequent priming and cycling of the lagging strand polymerase to the new... (Review)
Review
As the replication fork progresses, synthesis of the discontinuous lagging strand requires frequent priming and cycling of the lagging strand polymerase to the new primers. It appears that this mechanism also permits bypass of template lesions on both strands, leaving the damage behind in a single-strand gap and precluding fork stalling or collapse.
Topics: DNA Replication; DNA-Directed DNA Polymerase; Escherichia coli; Eukaryotic Cells; Multienzyme Complexes
PubMed: 16857582
DOI: 10.1016/j.molcel.2006.05.034 -
Nature Structural & Molecular Biology Mar 2021Cellulose is frequently found in communities of sessile bacteria called biofilms. Escherichia coli and other enterobacteriaceae modify cellulose with phosphoethanolamine...
Cellulose is frequently found in communities of sessile bacteria called biofilms. Escherichia coli and other enterobacteriaceae modify cellulose with phosphoethanolamine (pEtN) to promote host tissue adhesion. The E. coli pEtN cellulose biosynthesis machinery contains the catalytic BcsA-B complex that synthesizes and secretes cellulose, in addition to five other subunits. The membrane-anchored periplasmic BcsG subunit catalyzes pEtN modification. Here we present the structure of the roughly 1 MDa E. coli Bcs complex, consisting of one BcsA enzyme associated with six copies of BcsB, determined by single-particle cryo-electron microscopy. BcsB homo-oligomerizes primarily through interactions between its carbohydrate-binding domains as well as intermolecular beta-sheet formation. The BcsB hexamer creates a half spiral whose open side accommodates two BcsG subunits, directly adjacent to BcsA's periplasmic channel exit. The cytosolic BcsE and BcsQ subunits associate with BcsA's regulatory PilZ domain. The macrocomplex is a fascinating example of cellulose synthase specification.
Topics: Biocatalysis; Cellulose; Cryoelectron Microscopy; Escherichia coli; Escherichia coli Proteins; Models, Molecular; Multienzyme Complexes; Protein Subunits; Reproducibility of Results
PubMed: 33712813
DOI: 10.1038/s41594-021-00569-7 -
The Biochemical Journal Dec 1989Multienzyme complexes and multifunctional proteins may confer a kinetic advantage by channelling reaction intermediates between consecutive enzymes and reducing the...
Multienzyme complexes and multifunctional proteins may confer a kinetic advantage by channelling reaction intermediates between consecutive enzymes and reducing the transient time for the establishment of steady states. A general means for quantitatively assessing the contribution of channelling to the reduction of pool size and transient time is presented. Restrictions to the kinetic advantage are identified, and it is shown that no channelling advantage is obtained at high enzyme concentration or for enzymes which exhibit rapid-equilibrium kinetic behaviour.
Topics: Kinetics; Mathematics; Models, Theoretical; Multienzyme Complexes; Protein Binding
PubMed: 2604733
DOI: 10.1042/bj2640605 -
Journal of Bacteriology Mar 1992A major-high-molecular mass proteinase and seven latent minor proteinases were found in cell extracts and in concentrates of culture medium from Frankia sp. strain BR...
A major-high-molecular mass proteinase and seven latent minor proteinases were found in cell extracts and in concentrates of culture medium from Frankia sp. strain BR after nondenaturing electrophoresis in mixed gelatin-polyacrylamide gels. All of these complexes showed multicatalytic properties. Their molecular masses and their sedimentation coefficients varied from 1,300 kDa (28S) to 270 kDa (12S). The electroeluted 1,300-kDa proteinase complex dissociated into 11 low-molecular-mass proteinases (40 to 19 kDa) after sodium dodecyl sulfate activation at 30 degrees C and electrophoresis under denaturing conditions. All of these electroeluted proteinases hydrolyzed N-carbobenzoxy-Pro-Ala-Gly-Pro-4-methoxy-beta- naphthylamide, D-Val-Leu-Arg-4-methoxy-beta-naphthylamide, and Boc-Val-Pro-Arg-4-methyl-7-coumarylamide, whereas Suc-Leu-Leu-Val-Tyr-4-methyl-7-coumarylamide was cleaved only by the six lower-molecular-mass proteinases (27.5 to 19 kDa). Examination by electron microscopy of uranyl acetate-stained, electroeluted 1,300- and 650-kDa intracellular and extracellular proteinase complexes showed ring-shaped and cylindrical particles (10 to 11 nm in diameter, 15 to 16 nm long) similar to those of eukaryotic prosomes and proteasomes. Polyclonal antibodies raised against rat skeletal muscle proteasomes cross-reacted with all of the high-molecular-mass proteinase complexes and, after denaturation of the electroeluted 1,300-kDa band, with polypeptides of 35 to 38, 65, and 90 kDa. Electrophoresis of the activated cell extracts under denaturing conditions revealed 11 to 17 gelatinases from 40 to 19 kDa, including the 11 proteinases of the 1,300-kDa proteinase complex. The inhibition pattern of these proteinases is complex. Thiol-reactive compounds and 1-10-phenanthroline strongly inhibited all of the proteinases, but inhibitors against serine-type proteinases were also effective for most of them.
Topics: Actinomycetales; Centrifugation, Density Gradient; Cross Reactions; Cysteine Endopeptidases; Electrophoresis, Polyacrylamide Gel; Endopeptidases; Enzyme Activation; Gelatin; Macromolecular Substances; Microscopy, Electron; Multienzyme Complexes; Negative Staining; Protease Inhibitors; Proteasome Endopeptidase Complex; Subcellular Fractions; Substrate Specificity
PubMed: 1537794
DOI: 10.1128/jb.174.5.1495-1504.1992 -
European Journal of Biochemistry Feb 1990The association of different enzymes into a complex may induce changes in the kinetic parameters of its component enzymes. This implies that they cannot be treated as... (Review)
Review
The association of different enzymes into a complex may induce changes in the kinetic parameters of its component enzymes. This implies that they cannot be treated as independent catalysts. It will affect the formulations and theorems of control analysis and necessitates the introduction of additional elasticities reflecting the effect of one enzyme on the rate of another. We show how this is achieved as an extension of the classical treatment. We present modified summation and connectivity theorems incorporating both homologous and heterologous interactions. The case of channelling of metabolites in such complexes is considered and an experimental method for its detection is suggested.
Topics: Catalysis; Enzymes; Kinetics; Mathematics; Models, Theoretical; Multienzyme Complexes
PubMed: 2406133
DOI: 10.1111/j.1432-1033.1990.tb15330.x -
Arthritis Research 2001The anti-PM/Scl autoantibodies are known to characterize a subset of autoimmune patients with myositis, scleroderma (Scl), and the PM/Scl overlap syndrome. The major... (Review)
Review
The anti-PM/Scl autoantibodies are known to characterize a subset of autoimmune patients with myositis, scleroderma (Scl), and the PM/Scl overlap syndrome. The major autoantigens that are recognized by anti-PM/Scl autoantibodies are designated PM/Scl-100 and PM/Scl-75. These autoantigens have been reported to associate into a large complex consisting of 11 to 16 proteins and to play a role in ribosome synthesis. Recently, it was discovered that the PM/Scl complex is the human counterpart of the yeast (Saccharomyces cerevisiae) exosome, which is an RNA-processing complex consisting of 11 3' --> 5' exoribonucleases. To date, 10 human exosome components have been identified, although only some of these were studied in more detail. In this review, we discuss some recent advances in the characterization of the PM/Scl complex.
Topics: Autoantigens; Exoribonucleases; Exosome Multienzyme Ribonuclease Complex; Humans; Multienzyme Complexes; Polymyositis; Scleroderma, Systemic
PubMed: 11178117
DOI: 10.1186/ar147 -
FEBS Letters Jun 1996Many succinate:quinone oxidoreductases in bacteria and mitochondria, i.e. succinate:quinone reductases and fumarate reductases, contain in the membrane anchor a... (Review)
Review
Many succinate:quinone oxidoreductases in bacteria and mitochondria, i.e. succinate:quinone reductases and fumarate reductases, contain in the membrane anchor a cytochrome b whose structure and function is poorly understood. Based on biochemical data and polypeptide sequence information, we show that the anchors in different organisms are related despite an apparent diversity in polypeptide and heme composition. A general structural model for the membrane-integral domain of the anchors is proposed. It is an antiparallel four-helix bundle with a novel arrangement of hexa-coordinated protoheme IX. The structure can be applied to a larger group of membrane-integral cytochromes of b-type and has evolutionary and functional implications.
Topics: Amino Acid Sequence; Animals; Binding Sites; Cell Membrane; Cytochrome c Group; Electron Transport Complex II; Models, Molecular; Molecular Sequence Data; Multienzyme Complexes; Oxidoreductases; Succinate Dehydrogenase
PubMed: 8682198
DOI: 10.1016/0014-5793(96)00529-7