Characterization of stable humic–enzyme complexes of different soil ecosystems through analytical isoelectric focussing technique (IEF)

Transcriptional regulation in eukaryotes occurs within a chromatin setting, and is strongly influenced by the post-translational modification of histones, the building blocks of chromatin, such as methylation, phosphorylation and acetylation. Acetylation is probably the best understood of these modifications: hyperacetylation leads to an increase in the expression of particular genes, and hypoacetylation has the opposite effect. Many studies have identified several large, multisubunit enzyme complexes that are responsible for the targeted deacetylation of histones. The aim of this review is to give a comprehensive overview of the structure, function and tissue distribution of members of the classical histone deacetylase (HDAC) family, in order to gain insight into the regulation of gene expression through HDAC activity. SAGE (serial analysis of gene expression) data show that HDACs are generally expressed in almost all tissues investigated. Surprisingly, no major differences were observed between the expression pattern in normal and malignant tissues. However, significant variation in HDAC expression was observed within tissue types. HDAC inhibitors have been shown to induce specific changes in gene expression and to influence a variety of other processes, including growth arrest, differentiation, cytotoxicity and induction of apoptosis. This challenging field has generated many fascinating results which will ultimately lead to a better understanding of the mechanism of gene transcription as a whole.

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Post-translational modification in the archaea: structural characterization of multi-enzyme complex lipoylation

Biochemical Journal ◽

10.1042/bj20121150 ◽

2012 ◽

Vol 449 (2) ◽

pp. 415-425 ◽

Cited By ~ 8

Author(s):

Mareike G. Posner ◽

Abhishek Upadhyay ◽

Susan J. Crennell ◽

Andrew J. A. Watson ◽

Steve Dorus ◽

...

Keyword(s):

Conformational Change ◽

Lipoic Acid ◽

Covalent Attachment ◽

Post Translational Modification ◽

Thermophilic Archaeon ◽

C Complex ◽

Biochemical Analyses ◽

Enzyme Complexes ◽

Lipoyl Domain

Lipoylation, the covalent attachment of lipoic acid to 2-oxoacid dehydrogenase multi-enzyme complexes, is essential for metabolism in aerobic bacteria and eukarya. In Escherichia coli, lipoylation is catalysed by LplA (lipoate protein ligase) or by LipA (lipoic acid synthetase) and LipB [lipoyl(octanoyl) transferase] combined. Whereas bacterial and eukaryotic LplAs comprise a single two-domain protein, archaeal LplA function typically involves two proteins, LplA-N and LplA-C. In the thermophilic archaeon Thermoplasma acidophilum, LplA-N and LplA-C are encoded by overlapping genes in inverted orientation (lpla-c is upstream of lpla-n). The T. acidophilum LplA-N structure is known, but the LplA-C structure is unknown and LplA-C's role in lipoylation is unclear. In the present study, we have determined the structures of the substrate-free LplA-N–LplA-C complex and E2lipD (dihydrolipoyl acyltransferase lipoyl domain) that is lipoylated by LplA-N–LplA-C, and carried out biochemical analyses of this archaeal lipoylation system. Our data reveal the following: (i) LplA-C is disordered but folds upon association with LplA-N; (ii) LplA-C induces a conformational change in LplA-N involving substantial shortening of a loop that could repress catalytic activity of isolated LplA-N; (iii) the adenylate-binding region of LplA-N–LplA-C includes two helices rather than the purely loop structure of varying order observed in other LplA structures; (iv) LplAN–LplA-C and E2lipD do not interact in the absence of substrate; (v) LplA-N–LplA-C undergoes a conformational change (the details of which are currently undetermined) during lipoylation; and (vi) LplA-N–LplA-C can utilize octanoic acid as well as lipoic acid as substrate. The elucidated functional inter-dependence of LplA-N and LplA-C is consistent with their evolutionary co-retention in archaeal genomes.

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Characterization of cellulolytic enzyme complexes obtained from mutants of Trichoderma reesei with enhanced cellulase production

European Journal of Applied Microbiology and Biotechnology ◽

10.1007/bf00508113 ◽

1981 ◽

Vol 12 (1) ◽

pp. 16-21 ◽

Cited By ~ 12

Author(s):

Ivica Labudová ◽

Vladimir Farkaš ◽

Štefan Bauer ◽

Nadežda Kolarová ◽

Alexander Brányik

Keyword(s):

Trichoderma Reesei ◽

Cellulase Production ◽

Cellulolytic Enzyme ◽

Enzyme Complexes

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Separation and characterization of a foetal haemoglobin variant by means of isoelectric focussing

Life Sciences ◽

10.1016/0024-3205(71)90017-8 ◽

1971 ◽

Vol 10 (4) ◽

pp. 191-194 ◽

Cited By ~ 7

Author(s):

I.R.F. Brown ◽

J.L. Grech

Keyword(s):

Foetal Haemoglobin ◽

Isoelectric Focussing ◽

Haemoglobin Variant

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Functional Characterization and Target Validation of Alternative Complex I of Plasmodium falciparum Mitochondria

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.50.5.1841-1851.2006 ◽

2006 ◽

Vol 50 (5) ◽

pp. 1841-1851 ◽

Cited By ~ 84

Author(s):

Giancarlo A. Biagini ◽

Parnpen Viriyavejakul ◽

Paul M. O'Neill ◽

Patrick G. Bray ◽

Stephen A. Ward

Keyword(s):

Plasmodium Falciparum ◽

Complex I ◽

Functional Characterization ◽

Proton Pumping ◽

Confocal Imaging ◽

Q Cycle ◽

Transport Chain ◽

Diphenylene Iodonium ◽

Enzyme Complexes

ABSTRACT This study reports on the first characterization of the alternative NADH:dehydrogenase (also known as alternative complex I or type II NADH:dehydrogenase) of the human malaria parasite Plasmodium falciparum, known as PfNDH2. PfNDH2 was shown to actively oxidize NADH in the presence of quinone electron acceptors CoQ1 and decylubiquinone with an apparent Km for NADH of approximately 17 and 5 μM, respectively. The inhibitory profile of PfNDH2 revealed that the enzyme activity was insensitive to rotenone, consistent with recent genomic data indicating the absence of the canonical NADH:dehydrogenase enzyme. PfNDH2 activity was sensitive to diphenylene iodonium chloride and diphenyl iodonium chloride, known inhibitors of alternative NADH:dehydrogenases. Spatiotemporal confocal imaging of parasite mitochondria revealed that loss of PfNDH2 function provoked a collapse of mitochondrial transmembrane potential (Ψm), leading to parasite death. As with other alternative NADH:dehydrogenases, PfNDH2 lacks transmembrane domains in its protein structure, and therefore, it is proposed that this enzyme is not directly involved in mitochondrial transmembrane proton pumping. Rather, the enzyme provides reducing equivalents for downstream proton-pumping enzyme complexes. As inhibition of PfNDH2 leads to a depolarization of mitochondrial Ψm, this enzyme is likely to be a critical component of the electron transport chain (ETC). This notion is further supported by proof-of-concept experiments revealing that targeting the ETC's Q-cycle by inhibition of both PfNDH2 and the bc 1 complex is highly synergistic. The potential of targeting PfNDH2 as a chemotherapeutic strategy for drug development is discussed.

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Interactions of Dehydrogenase Enzymes with Nanoparticles Industrial and Medical Applications and Challenges: Mini-review

Mini-Reviews in Medicinal Chemistry ◽

10.2174/1570193x17666201119152944 ◽

2020 ◽

Vol 20 ◽

Author(s):

Samaneh Jafari Porzani ◽

Adriana Sturion Lorenzi ◽

Masoumeh Eghtedari ◽

Bahareh Nowruzi

Keyword(s):

Quantum Dots ◽

Lactate Dehydrogenase ◽

Protein Interactions ◽

Interfacial Layer ◽

Current Knowledge ◽

Model Systems ◽

Medical Applications ◽

Enzyme Formation ◽

Enzyme Complexes

: The general overview aimed to increase the current knowledge interactions between dehydrogenase enzymes and nanoparticles, and introduce dehydrogenases for industrial and health purposes. Nanoparticles (NPs) are particles constituting from 1 to 100 nm based on their size with a surrounding interfacial layer. Nanoparticle-Protein interactions include covalent and non-covalent attachments. Several dehydrogenase enzymes (e.g., alcohol dehydrogenase, lactate dehydrogenase, alanine dehydrogenase, glutamate dehydrogenase, leucine dehydrogenase, phenylalanine dehydrogenase, and malate dehydrogenase) are used for immobilization by nanoparticles. Such as magnetic nanoparticles and quantum dots, represent attractive model systems for biological enzyme assemblies and design of bioanalytical sensors. Further, bioconjugation of nanoparticles with dehydrogenase enzymes has broad applications in biocatalysis and nanomedicine for drug discovery. However, studies on the characterization of nanoparticle-enzyme complexes accept apparent that the anatomy and action of enzymes are afflicted by the chemistry of nanoparticle ligand, size, actual, and labeling methods. Moreover, the nanoparticle-protein conjugation revealed increased/decreased enzymatic activity due to nanoparticle features. Thus, this work reviewed the findings of nanoparticle-enzyme interactions for nanotechnology applications and conjugation techniques. We also highlight several challenges associated with the nanoparticle-enzyme interactions, including stability and reusability of the enzymes in nanoparticle-enzyme formation.

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Complementary substrate specificity and distinct quaternary assembly of the Escherichia coli aerobic and anaerobic β-oxidation trifunctional enzyme complexes

Biochemical Journal ◽

10.1042/bcj20190314 ◽

2019 ◽

Vol 476 (13) ◽

pp. 1975-1994 ◽

Cited By ~ 1

Author(s):

Shiv K. Sah-Teli ◽

Mikko J. Hynönen ◽

Werner Schmitz ◽

James A. Geraets ◽

Jani Seitsonen ◽

...

Keyword(s):

Escherichia Coli ◽

Kinetic Studies ◽

Biophysical Characterization ◽

Aerobic Conditions ◽

Membrane Bound ◽

Quaternary Assembly ◽

Enzyme Complexes ◽

Aerobic And Anaerobic ◽

Long Chain

AbstractThe trifunctional enzyme (TFE) catalyzes the last three steps of the fatty acid β-oxidation cycle. Two TFEs are present in Escherichia coli, EcTFE and anEcTFE. EcTFE is expressed only under aerobic conditions, whereas anEcTFE is expressed also under anaerobic conditions, with nitrate or fumarate as the ultimate electron acceptor. The anEcTFE subunits have higher sequence identity with the human mitochondrial TFE (HsTFE) than with the soluble EcTFE. Like HsTFE, here it is found that anEcTFE is a membrane-bound complex. Systematic enzyme kinetic studies show that anEcTFE has a preference for medium- and long-chain enoyl-CoAs, similar to HsTFE, whereas EcTFE prefers short chain enoyl-CoA substrates. The biophysical characterization of anEcTFE and EcTFE shows that EcTFE is heterotetrameric, whereas anEcTFE is purified as a complex of two heterotetrameric units, like HsTFE. The tetrameric assembly of anEcTFE resembles the HsTFE tetramer, although the arrangement of the two anEcTFE tetramers in the octamer is different from the HsTFE octamer. These studies demonstrate that EcTFE and anEcTFE have complementary substrate specificities, allowing for complete degradation of long-chain enoyl-CoAs under aerobic conditions. The new data agree with the notion that anEcTFE and HsTFE are evolutionary closely related, whereas EcTFE belongs to a separate subfamily.

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