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1.
D. Robinette S. Wada T. Arroll M. G. Levy W. L. Miller E. J. Noga 《Cellular and molecular life sciences : CMLS》1998,54(5):467-475
Three antibacterial proteins were isolated from acid extracts of channel catfish (Ictalurus punctatus) skin by cation exchange chromatography and reverse-phase high-pressure liquid chromatography. The molecular masses of the
proteins were 15.5, 15.5 and 30 kD as determined by SDS-polyacrylamide gel electrophoresis. Mass spectrometry, amino acid
composition and amino acid sequence data suggest that the most abundant protein is closely related to histone H2B. The H2B-like
protein was inhibitory to Aeromonas hydrophila and Saprolegnia spp., which are important bacterial and fungal pathogens of fish. These findings suggest that histones may be important defensive
molecules in fish.
Received 22 December 1997; received after revision 5 March 1998; accepted 5 March 1998 相似文献
2.
Alexander G. McLennan 《Cellular and molecular life sciences : CMLS》2013,70(3):373-385
Many members of the nudix hydrolase family exhibit considerable substrate multispecificity and ambiguity, which raises significant issues when assessing their functions in vivo and gives rise to errors in database annotation. Several display low antimutator activity when expressed in bacterial tester strains as well as some degree of activity in vitro towards mutagenic, oxidized nucleotides such as 8-oxo-dGTP. However, many of these show greater activity towards other nucleotides such as ADP-ribose or diadenosine tetraphosphate (Ap4A). The antimutator activities have tended to gain prominence in the literature, whereas they may in fact represent the residual activity of an ancestral antimutator enzyme that has become secondary to the more recently evolved major activity after gene duplication. Whether any meaningful antimutagenic function has also been retained in vivo requires very careful assessment. Then again, other examples of substrate ambiguity may indicate as yet unexplored regulatory systems. For example, bacterial Ap4A hydrolases also efficiently remove pyrophosphate from the 5′ termini of mRNAs, suggesting a potential role for Ap4A in the control of bacterial mRNA turnover, while the ability of some eukaryotic mRNA decapping enzymes to degrade IDP and dIDP or diphosphoinositol polyphosphates (DIPs) may also be indicative of new regulatory networks in RNA metabolism. DIP phosphohydrolases also degrade diadenosine polyphosphates and inorganic polyphosphates, suggesting further avenues for investigation. This article uses these and other examples to highlight the need for a greater awareness of the possible significance of substrate ambiguity among the nudix hydrolases as well as the need to exert caution when interpreting incomplete analyses. 相似文献
3.
Gineitis A Treigyte G Savickiene J Shanbhag VP Stigbrand T 《Cellular and molecular life sciences : CMLS》1999,55(2):317-326
The two-dimensional electrophoretic patterns of nuclear proteins and their tyrosine phosphorylation were compared for HL-60
cells before and after differentiation induction to granulocytes by dimethyl sulfoxide, all-trans retinoic acid and N
6,O
2-dibutyryl adenosine 3′5′-cyclic monophosphate. Regardless of the inducer used, some nuclear proteins, which are tyrosine-phosphorylated
in proliferating HL-60 cells, undergo gradual dephosphorylation 12–72 h after induction of differentiation, followed by drastic
dephosphorylation during maturation to granulocytes. At least 13 nuclear proteins with a molecular mass of 35–110 kDa are
dephosphorylated, and 6 nuclear proteins undergo tyrosine phosphorylation. Analysis of the nuclear proteins differentially
extracted by salt and detergents indicates that changes in their tyrosine phosphorylation during the maturation stage of differentiating
granulocytes occur mainly in proteins which are abundant in nucleoplasm, chromatin and residual nuclear structures. The abundance
of these proteins, residing in the nuclear structures, and their long-term modification in phosphorylation during the maturation
stages of differentiation strongly suggest that tyrosine phosphorylation of these proteins is involved in reorganization of
the differentiating cell nucleus.
Received 21 September 1998; received after revision 24 November 1998; accepted 3 December 1998 相似文献
4.
L. Fanuel I. Thamm V. Kostanjevecki B. Samyn B. Joris C. Goffin J. Brannigan J. Van Beeumen J. M. Frère 《Cellular and molecular life sciences : CMLS》1999,55(5):812-818
Two new enzymes which hydrolyse D-alanyl-p-nitroanilide have been detected in Ochrobactrum anthropi LMG7991 extracts. The first enzyme, DmpB, was purified to homogeneity and found to be homologous to the Dap protein produced
by O. anthropi SCRC C1-38 (ATCC49237). The second enzyme, DmpA, exhibits a similar substrate profile when tested on p-nitroanilide derivatives
of glycine and L/D-alanine, but the amounts produced by the Ochrobactrum strain were not sufficient to allow complete purification. Interestingly, the DmpA preparation also exhibited an L-aminopeptidase
activity on the tripeptide L-Ala-Gly-Gly but it was not possible to be certain that the same protein was responsible for both
p-nitroanilide and peptide hydrolysing activities. The gene encoding the DmpA protein was cloned and sequenced. The deduced
protein sequence exhibits varying degrees of similarity with those corresponding to several open reading frames found in the
genomes of other prokaryotic organisms, including Mycobacteria. None of these gene products has been isolated or characterised,
but a tentative relationship can be proposed with the NylC amidase from Flavobacterium sp. K172.
Received 7 December 1998; received after revision 15 March 1999; accepted 22 March 1999 相似文献
5.
The selection of novel proteins or enzymes from random protein libraries has come to be a major objective in current biology,
and these enzymes should prove useful in various biological and biomedical fields. New technologies such as in vitro selection
of proteins in cell-free systems have high potential to realize evolu tionary molecular engineering of proteins. This review
highlights an application of insertional mutagenesis of proteins to evolutionary molecular engineering. Random sequence proteins
are inserted into the surface of a host enzyme which serves as a scaffold to display random protein libraries. Constraints
on random polypeptide conformations owing to the proximity of N- and C-termini on the scaffold would result in greater screening
efficiency of libraries. The scaffold enzyme is also used as a probe for monitoring the hill climbing of random sequence proteins
on a fitness landscape and navigating rapid protein folding in the sequence space.
Received 9 October 1997; received after revision 6 January 1998; accepted 19 January 1998 相似文献
6.
van Roermund CW Waterham HR Ijlst L Wanders RJ 《Cellular and molecular life sciences : CMLS》2003,60(9):1838-1851
Peroxisomes are essential subcellular organelles involved in a variety of metabolic processes. Their importance is underlined by the identification of a large group of inherited diseases in humans in which one or more of the peroxisomal functions are impaired. The yeast Saccharomyces cerevisiae has been used as a model organism to study the functions of peroxisomes. Efficient oxidation of fatty acids does not only require the participation of peroxisomal enzymes but also the active involvement of other gene products. One group of important gene products in this respect includes peroxisomal membrane proteins involved in metabolite transport. This overview discusses the various aspects of fatty acid -oxidation in S. cerevisiae. Addressed are the various enzymes and their particular functions as well as the various transport mechanisms to take up fatty acids into peroxisomes or to export the -oxidation products out of the peroxisome to mitochondria for full oxidation to CO2 and H2O.Received 19 February 2003; received after revision 27 March 2003; accepted 27 March 2003 相似文献
7.
C. Elsing J. Górski C. Boeker W. Stremmel 《Cellular and molecular life sciences : CMLS》1998,54(7):744-750
Studies of regulation of free fatty acid (FFA) utilization by skeletal muscles have focused on plasma FFA delivery and on
intracellular factors affecting FFA metabolism. The present study was conducted to directly analyse the uptake process of
fatty acids into single myocytes. Cells were isolated from the rat flexor digitorum brevis muscle. Confocal laser scanning
microscopy was utilized to analyse the uptake of the fluorescent fatty acid derivative 12-NBD-stearate, which is not metabolized
by muscle tissue. Uptake represented a saturable function of the unbound fatty acid concentration in the medium (K
m 366 ± 118 nM, V
max 2.1 ± 0.3 AU/s) and depended on the medium sodium concentration. Reduced buffer pH increased initial uptake rates, whereas
lactate (10 mM) had no effect. Membrane hyper- and depolarization decreased uptake rates. This study demonstrates for the
first time kinetic data from isolated myocytes with evidence for a carrier-mediated transport mechanism for long-chain fatty
acids.
Received 31 March 1998; accepted 8 May 1998 相似文献
8.
The targeting and anchoring of heterologous proteins and peptides to the outer surface of bacteriophages and cells is becoming increasingly important, and has been employed as a tool for fundamental and applied research in microbiology, molecular biology, vaccinology, and biotechnology. Less known are endospores or spores produced by some Gram-positive species. Spores of Bacillus subtilis are surrounded by a spore coat on their outside, and a few proteins have been identified being located on the outside layer and have been successfully used to immobilize antigens and some other proteins and enzymes. The major advantage of spores over the other published systems is their synthesis within the cytoplasm of the bacterial cell. Therefore, any heterologous protein to be anchored on the outside does not have to cross any membrane. Furthermore, spores are extremely resistant against high temperature, irradiation and many chemicals, and can be stored for many years at room temperature. 相似文献
9.
Makarchikov AF Lakaye B Gulyai IE Czerniecki J Coumans B Wins P Grisar T Bettendorff L 《Cellular and molecular life sciences : CMLS》2003,60(7):1477-1488
In most organisms, the main form of thiamine is the coenzyme thiamine diphosphate. Thiamine
triphosphate (ThTP) is also found in low amounts in most vertebrate tissues and can phosphorylate
certain proteins. Here we show that ThTP exists not only in vertebrates but is present in bacteria,
fungi, plants and invertebrates. Unexpectedly, we found that in
Escherichia coli as well as in
Arabidopsis thaliana, ThTP was synthesized only under particular
circumstances such as hypoxia (E. coli) or withering
(A. thaliana). In mammalian tissues, ThTP concentrations
are regulated by a specific thiamine triphosphatase that we have recently characterized. This enzyme
was found only in mammals. In other organisms, ThTP can be hydrolyzed by unspecific phosphohydrolases.
The occurrence of ThTP from prokaryotes to mammals suggests that it may have a basic role in cell
metabolism or cell signaling. A decreased content may contribute to the symptoms observed during
thiamine deficiency.Received 7 March 2003; received after revision 11 April 2003; accepted 14 April 2003 相似文献
10.
Sánchez-Margalet V González-Yanes C Santos-Alvarez J Najib S 《Cellular and molecular life sciences : CMLS》1999,55(1):142-147
Insulin action is initiated by binding to its cognate receptor, which then triggers multiple cellular responses by activating
different signaling pathways. There is evidence that insulin receptor signaling may involve G protein activation in different
target cells. We have studied the activation of G proteins in rat hepatoma (HTC) cells. We found that insulin stimulated binding
of guanosine 5′-O-(3-thiotriphosphate) (GTP-γ-35S) to plasma membrane proteins of HTC cells, in a dose-dependent manner. This effect was completely blocked by pertussis toxin
treatment of the membranes, suggesting the involvement of G proteins of the Gα
i/Gα
o family. The expression of these Gα proteins was checked by Western blotting. Next, we used blocking antibodies to sort out the specific Gα protein activated by insulin stimulation. Anti-Gα
il,2 antibodies completely prevented insulin-stimulated GTP binding, whereas anti-Gα
o,i3 did not modify this effect of insulin on GTP binding. Moreover, we found physical association of the insulin receptor with
Gα
i1,2 by copurification studies. These results further support the involvement of a pertussis toxin-sensitive G protein in insulin
receptor signaling and provides some evidence of specific association and activation of Gα
i1,2 protein by insulin. These findings suggest that Gα
i1,2 proteins might be involved in insulin action.
Received 23 September 1998; received after revision 23 November 1998; accepted 25 November 1998 相似文献
11.
The cytochrome P450s are a superfamily of hemoprotein enzymes responsible for the metabolism of a wide variety of xenobiotic
and endogenous compounds. The individual P450s exhibit unique substrate specificity and stereoselectivity profiles which reflect
corresponding differences in primary sequence and tertiary structure. In the absence of an experimental structure, models
for mammalian P450s have been generated by their homology with bacterial P450s of known structure. The rather low sequence
identity between target and template proteins renders P450 modeling a challenging task. However, the substrate recognition
properties of several P450s are consistent with recently developed working models. This review summarizes the major concepts
and current approaches of molecular modeling of P450s.
Received 28 September 1999; received after revision 25 November 1999; accepted 31 December 1999 相似文献
12.
Jedrzejas MJ 《Cellular and molecular life sciences : CMLS》2007,64(21):2799-2822
Bacteria present a variety of molecules either on their surface or in a cell-free form. These molecules take part in numerous
processes in the interactions with their host, with its tissues and other molecules. These molecules are essential to bacterial
pathogenesis either during colonization or the spread/invasion stages, and most are virulence factors. This review is focused
on such molecules using Streptococcus pneumoniae, a Gram-positive bacterium, as an example. Selected surface proteins are introduced, their structure described, and, whenever
available, their mechanisms of function on an atomic level are explained. Such mechanisms for hyaluronate lyase, pneumococcal
surface protein A, pneumolysin, histidine-triad and fibronectin-binding proteins are discussed. Elucidation of molecular mechanisms
of virulence factors is essential for the understanding of bacteria and their functional properties. Structural biology appears
pivotal for these studies, as structural and mechanistic insights facilitate rational approach to the development of new treatments.
Received 12 March 2007; received after revision 28 June 2007; accepted 18 July 2007 相似文献
13.
Danielle Kamato Partha Mitra Felicity Davis Narin Osman Rebecca Chaplin Peter J. Cabot Rizwana Afroz Walter Thomas Wenhua Zheng Harveen Kaur Margaret Brimble Peter J. Little 《Cellular and molecular life sciences : CMLS》2017,74(8):1379-1390
Seven transmembrane G protein-coupled receptors (GPCRs) have gained much interest in recent years as it is the largest class among cell surface receptors. G proteins lie in the heart of GPCRs signalling and therefore can be therapeutically targeted to overcome complexities in GPCR responses and signalling. G proteins are classified into four families (Gi, Gs, G12/13 and Gq); Gq is further subdivided into four classes. Among them Gαq and Gαq/11 isoforms are most crucial and ubiquitously expressed; these isoforms are almost 88% similar at their amino acid sequence but may exhibit functional divergences. However, uncertainties often arise about Gαq and Gαq/11 inhibitors, these G proteins might also have suitability to the invention of novel-specific inhibitors for each isoforms. YM-254890 and UBO-QIC are discovered as potent inhibitors of Gαq functions and also investigated in thrombin protease-activated receptor (PAR)-1 inhibitors and platelet aggregation inhibition. The most likely G protein involved in PAR-1 stimulates responses is one of the Gαq family isoforms. In this review, we highlight the molecular structures and pharmacological responses of Gαq family which may reflect the biochemical and molecular role of Gαq and Gαq/11. The advanced understanding of Gαq and Gαq/11 role in GPCR signalling may shed light on our understanding on cell biology, cellular physiology and pathophysiology and also lead to the development of novel therapeutic agents for a number of diseases. 相似文献
14.
Peptidyl-prolyl cis-trans isomerases, a superfamily of ubiquitous folding catalysts 总被引:21,自引:0,他引:21
Cyclosporine A therapy for prophylaxis against graft rejection revolutionized human organ transplantation. The immunosuppressant
drugs cyclosporin A (CsA), FK506 and rapamycin block T-cell activation by interfering with the signal transduction pathway.
The target proteins for CsA and FK506 were found to be cyclophilins and FK506-binding proteins, (FKBPs), respectively. They
are unrelated in primary sequence, although both are peptidyl-prolyl cis-trans isomerases catalyzing the interconversion of
peptidyl-prolyl imide bonds in peptide and protein substrates. However, the prolyl isomerase activity of these proteins is
not essential for their immunosuppressive effects. Instead, the specific surfaces of the cyclophilin-CsA and FKBP-FK506 complexes
mediate the immunosuppressive action. Moreover, the natural cellular functions of all but a few remain elusive. In some cases
it could be demonstrated that prolyl isomerization is the rate-limiting step in protein folding in vitro, but many knockout
mutants of single and multiple prolyl isomerases were viable with no detectable phenotype. Even though a direct requirement
for in vivo protein folding could not be demonstrated, some important natural substrates of the prolyl isomerases are now
known, and they demonstrate the great variety of prolyl isomerization functions in the living cell: (i) A human cyclophilin
binds to the Gag polyprotein of the human immunodeficiency virus-1 (HIV-1) virion and was found to be essential for infection
with HIV to occur, probably by removal of the virion coat. (ii) Together with heat shock protein (HSP) 90, a member of the
chaperone family, high molecular weight cyclophilins and FKBPs bind and activate steroid receptors. This example also demonstrates
that prolyl isomerases act together with other folding enzymes, for example the chaperones, and protein disulfide isomerases.
(iii) An FKBP was found to act as a modulator of an intracellular calcium release channel. (iv) Along with the cyclophilins
and FKBPs, a third class of prolyl isomerases exist, the parvulins. The human parvulin homologue Pin1 is a mitotic regulator
essential for the G2/M transition of the eukaryotic cell cycle. These findings place proline isomerases at the intersection
of protein folding, signal transduction, trafficking, assembly and cell cycle regulation.
Received 18 September 1998; received after revision 4 November 1998; accepted 23 November 1998 相似文献
15.
The structure and function of heterotrimeric G protein subunits is known in considerable detail. Upon stimulation of a heptahelical
receptor by the appropriate agonists, the cognate G proteins undergo a cycle of activation and deactivation; the α-subunits and the βγ-dimers interact sequentially with several reaction partners (receptor, guanine nucleotides and effectors as well as regulatory
proteins) by exposing appropriate binding sites. For most of these domains, low molecular weight ligands have been identified
that either activate or inhibit signal transduction. These ligands include short peptides derived from receptors, G protein
subunits and effectors, mastoparan and related insect venoms, modified guanine nucleotides, suramin analogues and amphiphilic
cations. Because compounds that act on G proteins may be endowed with new forms of selectivity, we propose that G protein
subunits may therefore be considered as potential drug targets.
Received 18 September 1998; received after revision 6 November 1998; accepted 11 November 1998 相似文献
16.
Scavenger receptor family proteins: roles for atherosclerosis, host defence and disorders of the central nervous system 总被引:11,自引:1,他引:10
Y. Yamada T. Doi T. Hamakubo T. Kodama 《Cellular and molecular life sciences : CMLS》1998,54(7):628-640
In this review, we summarize the structure and function of the scavenger receptor family of proteins including class A (type
I and II macrophage scavenger receptors, MARCO), class B (CD36, scavenger receptor class BI), mucinlike (CD68/macrosialin,
dSR-CI) and endothelial (LOX-1) receptors. Two motifs have been identified as ligand-binding domains a charged collagen structure
of type I and II receptors, and an immunodominant domain of CD36. These structures can recognize a wide range of negatively
charged macromolecules, including oxidized low-density lipoproteins, damaged or apoptotic cells, and pathogenic microorganisms.
After binding, these ligands can be either internalized by endocytosis or phagocytosis, or remain at the cell surface and
mediate adhesion or lipid transfer through caveolae. Under physiological conditions, scavenger receptors serve to scavenge
or clean up cellular debris and other related materials, and they play a role in host defence. In pathological states, they
mediate the recruitment, activation and transformation of macrophages and other cells which may be related to the development
of atherosclerosis and to disorders caused by the accumulation of denatured materials, such as Alzheimer's disease.
Received 17 September 1997; received after revision 16 March 1998; accepted 17 March 1998 相似文献
17.
M. Mrksich 《Cellular and molecular life sciences : CMLS》1998,54(7):653-662
Substrates for studies of the interactions of attached cells with extracellular matrix components are often prepared by allowing
a protein to adsorb from solution onto a glass or polystyrene substrate. This method is simple and effective for many studies,
but it can fail in cases that require rigorous control over the structure and composition of adsorbed protein. Self-assembled
monolayers formed by the spontaneous ordering of terminally functionalized alkanethiols onto a gold substrate are a class
of well-ordered substrates and provide a convenient method for tailoring substrates with ligands, proteins and other groups.
Methods that can pattern the monolayers provide a general strategy to create substrates that control the size, shape and spacing
of attached cells. This review illustrates recent work that has used these methods of surface chemistry to create tailored
substrates for studies in cell biology.
Received 14 November 1997; received after revision 10 March 1998; accepted 10 March 1998 相似文献
18.
H. S. Lee Y. S. Kim S. B. Kim B. E. Choi B. H. Woo K. C. Lee 《Cellular and molecular life sciences : CMLS》1999,55(4):679-682
A mistletoe lectin was isolated from water extracts of Korean mistletoe, a subspecies of Viscum album, grown on Quercus mongolica using CM-Sepharose chromatography followed by an affinity chromatography on a concanavalin A-Sepharose column. The compound
proved to be a mistletoe lectin II with D-galactose and N-acetyl-D-galactosamine specificity. Matrix-assisted laser desorption time-of-flight mass spectroscopy showed it to have an
average molecular mass of 62.7 kDa and to consist of two subunits of 30.6 kDa and 32.5 kDa. It was a basic protein with isoelectric
points of 9.4 and 9.6 by capillary isoelectric focusing and was cytotoxic to Molt4 cell.
Received 17 November 1998; received after revision 3 March 1999; accepted 3 March 1999 相似文献
19.
Zheng-Bing Guan Quan Luo Hao-Ran Wang Yu Chen Xiang-Ru Liao 《Cellular and molecular life sciences : CMLS》2018,75(19):3569-3592
Multicopper oxidases (MCOs) are a pervasive family of enzymes that oxidize a wide range of phenolic and nonphenolic aromatic substrates, concomitantly with the reduction of dioxygen to water. MCOs are usually divided into two functional classes: metalloxidases and laccases. Given their broad substrate specificity and eco-friendliness (molecular oxygen from air as is used as the final electron acceptor and they only release water as byproduct), laccases are regarded as promising biological green tools for an array of applications. Among these laccases, those of bacterial origin have attracted research attention because of their notable advantages, including broad substrate spectrum, wide pH range, high thermostability, and tolerance to alkaline environments. This review aims to summarize the significant research efforts on the properties, mechanisms and structures, laccase-mediator systems, genetic engineering, immobilization, and biotechnological applications of the bacteria-source laccases and laccase-like enzymes, which principally include Bacillus laccases, actinomycetic laccases and some other species of bacterial laccases. In addition, these enzymes may offer tremendous potential for environmental and industrial applications. 相似文献
20.
Leukocyte integrins and inflammation 总被引:6,自引:0,他引:6
C. G. Gahmberg L. Valmu S. Fagerholm P. Kotovuori E. Ihanus L. Tian T. Pessa-Morikawa 《Cellular and molecular life sciences : CMLS》1998,54(6):549-555
Leukocyte adhesion is of pivotal functional importance. Without adequate adhesion, T lymphocytes and natural killer cells
are not cytotoxic, B cells cannot develop into antibody secreting plasma cells, leukocytes do not home into inflamed tissues
and myeloid cells are not able to phagocytize or exhibit chemotactic responses. During evolution several leukocyte adhesion
molecules have developed belonging to a few molecular families. Among these, the leukocyte-specific integrins (β
2 integrins, CD11/CD18 molecules) are among the most important. Much progress has taken place during the past few years, and
at present we have a considerable knowledge of their structure and function. Inflammation is critically dependent on integrin
activity, and its regulation forms the topic of this short review. 相似文献