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1.
Background
Medium chain length (mcl-) polyhydroxyalkanoates (PHA) are synthesized by many bacteria in the cytoplasm as storage compounds for energy and carbon. The key enzymes for PHA metabolism are PHA polymerase (PhaC) and depolymerase (PhaZ). Little is known of how mcl-PHA accumulation and degradation are controlled. It has been suggested that overall PHA metabolism is regulated by the β-oxidation pathway of which the flux is governed by intracellular ratios of [NADH]/[NAD] and [acetyl-CoA]/[CoA]. Another level of control could relate to modulation of the activities of PhaC and PhaZ. In order to investigate the latter, assays for in vitro activity measurements of PhaC and PhaZ in crude cell extracts are necessary. 相似文献2.
Elbanna K Lütke-Eversloh T Jendrossek D Luftmann H Steinbüchel A 《Archives of microbiology》2004,182(2-3):212-225
The biodegradability of microbial polythioesters (PTEs), a novel class of biopolymers which were discovered recently and can be produced by polyhydroxyalkanoate (PHA)-accumulating bacteria, was studied. Using poly(3-hydroxybutyrate-co-3-mercaptopropionate) [poly(3HB-co-3MP)] as sole carbon source for screening, 22 new bacterial strains were isolated and characterized. Interestingly, none of the PHA-degrading bacteria was able to utilize the homopolymer poly(3MP) as a carbon source for growth or to form clear zones on poly(3MP)-containing agar plates. The extracellular PHA depolymerases from two strains ( Schlegelella thermodepolymerans, Pseudomonas indica K2) were purified to electrophoretic homogeneity and biochemically characterized. The PHA depolymerase of S. thermodepolymerans exhibited a temperate optimum of about 75°C to 80°C and was stable at 70°C for more than 24 h. Regarding the substrate specificities of the PHA depolymerase of S. thermodepolymerans, enzyme activities decreased significantly with increasing 3MP content of the copolymer substrates. Interestingly, no activity could be detected with homoPTEs consisting only of 3MP or of 3-mercaptobutyrate. Similar results were obtained with the PHA depolymerases PhaZ2, PhaZ5 and PhaZ7 of Paucimonas lemoignei which were also investigated. The PHA depolymerase of Ps. indica K2 did not cleave any of the investigated polymers containing 3MP. Gas chromatography, infrared and 1H-NMR spectrometry and matrix-assisted laser desorption/ionization time-of-flight analysis revealed that 3MPs containing oligomers were enriched in the water-insoluble fraction remaining after partial digestion of poly(3HB-co-3MP) by purified poly(3HB) depolymerase of S. thermodepolymerans. In contrast, 3HB was enriched in the water-soluble fraction, which also contained 3HB-co-3MP dimer obtained by partial digestion of this copolymer by the enzyme. This study clearly indicates that PHA depolymerases are specific for oxoester linkages of PHAs and that the thioester bonds of PTEs cannot be cleaved by this type of enzyme.This publication is dedicated to Prof. Dr. Hans G. Schlegel in honor of his 80th birthday 相似文献
3.
Verena Kriechbaumer Linda Weigang Andreas Fießelmann Thomas Letzel Monika Frey Alfons Gierl Erich Glawischnig 《BMC plant biology》2008,8(1):44
Background
In bacteria, such as Salmonella typhimurium, tryptophan is synthesized from indole-3-glycerole phosphate (IGP) by a tryptophan synthase αββα heterotetramer. Plants have evolved multiple α (TSA) and β (TSB) homologs, which have probably diverged in biological function and their ability of subunit interaction. There is some evidence for a tryptophan synthase (TS) complex in Arabidopsis. On the other hand maize (Zea mays) expresses the TSA-homologs BX1 and IGL that efficiently cleave IGP, independent of interaction with TSB. 相似文献4.
Joshua B Kelley Ashley M Talley Adam Spencer Daniel Gioeli Bryce M Paschal 《BMC cell biology》2010,11(1):63
Background
Classical nuclear localization signal (NLS) dependent nuclear import is carried out by a heterodimer of importin α and importin β. NLS cargo is recognized by importin α, which is bound by importin β. Importin β mediates translocation of the complex through the central channel of the nuclear pore, and upon reaching the nucleus, RanGTP binding to importin β triggers disassembly of the complex. To date, six importin α family members, encoded by separate genes, have been described in humans. 相似文献5.
Vidushi S Patel Steven JB Cooper Janine E Deakin Bob Fulton Tina Graves Wesley C Warren Richard K Wilson Jennifer AM Graves 《BMC biology》2008,6(1):34
Background
Vertebrate alpha (α)- and beta (β)-globin gene families exemplify the way in which genomes evolve to produce functional complexity. From tandem duplication of a single globin locus, the α- and β-globin clusters expanded, and then were separated onto different chromosomes. The previous finding of a fossil β-globin gene (ω) in the marsupial α-cluster, however, suggested that duplication of the α-β cluster onto two chromosomes, followed by lineage-specific gene loss and duplication, produced paralogous α- and β-globin clusters in birds and mammals. Here we analyse genomic data from an egg-laying monotreme mammal, the platypus (Ornithorhynchus anatinus), to explore haemoglobin evolution at the stem of the mammalian radiation. 相似文献6.
A Paul Mould Jennifer A McLeish Julie Huxley-Jones Alexander C Goonesinghe Adam FL Hurlstone Raymond P Boot-Handford Martin J Humphries 《BMC cell biology》2006,7(1):24-15
Background
Integrins comprise a large family of α,β heterodimeric, transmembrane cell adhesion receptors that mediate diverse essential biological functions. Higher vertebrates possess a single β1 gene, and the β1 subunit associates with a large number of α subunits to form the major class of extracellular matrix (ECM) receptors. Despite the fact that the zebrafish (Danio rerio) is a rapidly emerging model organism of choice for developmental biology and for models of human disease, little is currently known about β1 integrin sequences and functions in this organism. 相似文献7.
Maria Grazia Di Certo Enrico M Batassa Ida Casella Annalucia Serafino Aristide Floridi Claudio Passananti Paola Molinari Elisabetta Mattei 《BMC cell biology》2008,9(1):56
Background
Chimeric proteins obtained by the fusion of a G protein-coupled receptor (GPCR) sequence to the N-terminus of the G protein α-subunit have been extensively used to investigate several aspects of GPCR signalling. Although both the receptor and the G protein generally maintain a fully functional state in such polypeptides, original observations made using a chimera between the β2-adrenergic receptor (β2AR) and Gαs indicated that the fusion to the α-subunit resulted in a marked reduction of receptor desensitization and down-regulation. To further investigate this phenomenon, we have compared the rates of internalization and recycling between wild-type and Gαs-fused β2AR. 相似文献8.
Shih-Lu Wu Chia-Cheng Li Jaw-Chyun Chen Yi-Jin Chen Ching-Ting Lin Tin-Yun Ho Chien-Yun Hsiang 《Journal of biomedical science》2009,16(1):6-14
Background
Endonuclease G (EndoG), a member of DNA/RNA nonspecific ββα-Me-finger nucleases, is involved in apoptosis and normal cellular proliferation. In this study, we analyzed the critical amino acid residues of EndoG and proposed the catalytic mechanism of EndoG. 相似文献9.
Jasmin Kirchner Emese Vissi Sascha Gross Balazs Szoor Andrey Rudenko Luke Alphey Helen White-Cooper 《BMC molecular biology》2008,9(1):36
Background
Protein phosphatase 1 (PP1) is involved in diverse cellular processes, and is targeted to substrates via interaction with many different protein binding partners. PP1 catalytic subunits (PP1c) fall into PP1α and PP1β subfamilies based on sequence analysis, however very few PP1c binding proteins have been demonstrated to discriminate between PP1α and PP1β. 相似文献10.
Background
The basal metabolic rate (BMR) of a mammal of mass M is commonly described by the power function αM β where α and β are constants determined by linear regression of the logarithm of BMR on the logarithm of M (i. e., β is the slope and α is the intercept in regression analysis). Since Kleiber's demonstration that, for 13 measurements of BMR, the logarithm of BMR is closely approximated by a straight line with slope 0.75, it has often been assumed that the value of β is exactly 3/4 (Kleiber's law). 相似文献11.
Huang-Chieh Lee Jen-Ning Tsai Pei-Yin Liao Wei-Yuan Tsai Kai-Yen Lin Chung-Cheng Chuang Chi-Kuang Sun Wen-Chang Chang Huai-Jen Tsai 《BMC developmental biology》2007,7(1):93
Background
Glycogen synthase kinase 3 (GSK3) encodes a serine/threonine protein kinase, is known to play roles in many biological processes. Two closely related GSK3 isoforms encoded by distinct genes: GSK3α (51 kDa) and GSK3β (47 kDa). In previously studies, most GSK3 inhibitors are not only inhibiting GSK3, but are also affecting many other kinases. In addition, because of highly similarity in amino acid sequence between GSK3α and GSK3β, making it difficult to identify an inhibitor that can be selective against GSK3α or GSK3β. Thus, it is relatively difficult to address the functions of GSK3 isoforms during embryogenesis. At this study, we attempt to specifically inhibit either GSK3α or GSK3β and uncover the isoform-specific roles that GSK3 plays during cardiogenesis. 相似文献12.
Rudresh Acharya Madhvi Gupta Suryanarayanarao Ramakumar Udupi A Ramagopal Virander S Chauhan 《BMC structural biology》2007,7(1):51
Background
The de novo design of peptides and proteins has recently surfaced as an approach for investigating protein structure and function. This approach vitally tests our knowledge of protein folding and function, while also laying the groundwork for the fabrication of proteins with properties not precedented in nature. The success of these studies relies heavily on the ability to design relatively short peptides that can espouse stable secondary structures. To this end, substitution with α, β-dehydroamino acids, especially α, β-dehydrophenylalanine (ΔPhe) comes in use for spawning well-defined structural motifs. Introduction of ΔPhe induces β-bends in small and 310-helices in longer peptide sequences. 相似文献13.
Background
Small loop-shaped motifs are common constituents of the three-dimensional structure of proteins. Typically they comprise between three and seven amino acid residues, and are defined by a combination of dihedral angles and hydrogen bonding partners. The most abundant of these are αβ-motifs, asx-motifs, asx-turns, β-bulges, β-bulge loops, β-turns, nests, niches, Schellmann loops, ST-motifs, ST-staples and ST-turns. 相似文献14.
Yan-Bin Teng Yong-Liang Jiang Yong-Xing He Wei-Wei He Fu-Ming Lian Yuxing Chen Cong-Zhao Zhou 《BMC structural biology》2009,9(1):67-8
Background
The carbonic anhydrases (CAs) are involved in inorganic carbon utilization. They have been classified into six evolutionary and structural families: α-, β-, γ-, δ-, ε-, ζ- CAs, with β-CAs present in higher plants, algae and prokaryotes. The yeast Saccharomyces cerevisiae encodes a single copy of β-CA Nce103/YNL036W. 相似文献15.
16.
Background
Despite the importance of β -strands as main building blocks in proteins, the propensity of amino acid in β -strands is not well-understood as it has been more difficult to determine experimentally compared to α -helices. Recent studies have shown that most of the amino acids have significantly high or low propensity towards both ends of β -strands. However, a comprehensive analysis of the sequence dependent amino acid propensities at positions between the ends of the β -strand has not been investigated. 相似文献17.
Background
Capping protein (CP), a heterodimer of α and β subunits, is found in all eukaryotes. CP binds to the barbed ends of actin filaments in vitro and controls actin assembly and cell motility in vivo. Vertebrates have three isoforms of CPβ produced by alternatively splicing from one gene; lower organisms have one gene and one isoform. 相似文献18.
Andrew MF Liu Rico KH Lo Emily X Guo Maurice KC Ho Richard D Ye Yung H Wong 《BMC structural biology》2011,11(1):17
Background
G protein-coupled receptors constitute the largest family of cell surface receptors in the mammalian genome. As the core of the G protein signal transduction machinery, the Gα subunits are required to interact with multiple partners. The GTP-bound active state of many Gα subunits can bind a multitude of effectors and regulatory proteins. Yet it remains unclear if the different proteins utilize distinct or common structural motifs on the Gα subunit for binding. Using Gα16 as a model, we asked if its recently discovered adaptor protein tetratricopeptide repeat 1 (TPR1) binds to the same region as its canonical effector, phospholipase Cβ (PLCβ). 相似文献19.
Introduction
The objective of this study was to model the effects of transforming growth factor beta (TGF-β) and platelet-derived growth factor (PDGF), both present in rheumatoid arthritis (RA) synovia, on the behavior of fibroblast-like synoviocytes (FLS) in response to pro-inflammatory cytokine (interleukin (IL)1β, tumor necrosis factor-alpha (TNFα)) challenge. 相似文献20.
Ola F Wetten Alexander J Nederbragt Robert C Wilson Kjetill S Jakobsen Rolf B Edvardsen Øivind Andersen 《BMC evolutionary biology》2010,10(1):315