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At least 217 records · Page 12Linked to original sources
PubMed1982

Lactoferrin binding to lysozyme-treated Micrococcus luteus.

When the cell lysis of Micrococcus luteus by hen egg white or human lysozyme is performed in the presence of bovine or human lactoferrin, a temporary increase of the turbidity of the solution as followed at 450 nm is observed. Examination of the suspension under light microscopy has proven that the protoplasts produced upon lysozyme action are agglutinated by lactoferrin. The rate of agglutination depends on pH, lactoferrin, lysozyme and cells concentrations. Agglutination is maximal at pH 5.5. Around 1.4 X 10(6) binding sites for lactoferrin per cell have been determined through a Scatchard plot analysis. The binding to the cells is not mediated by the glycosidic moiety of lactoferrin but rather by a charge-to charge interaction as succinylation of about four out of the 39 lysines of lactoferrin completely abolishes its ability to agglutinate the cells. Binding does not depend on ionic iron nor on the iron content of lactoferrin itself.

Animals↗
PubMed1982

NMR field-cycling relaxation spectroscopy of bovine serum albumin, muscle tissue, Micrococcus luteus and yeast. 14N1H-quadrupole dips.

The frequency dependence of the proton spin lattice relaxation time of bovine serum albumin, muscle tissue, Micrococcus luteus and yeast has been measured by the aid of the field-cycling technique. In all systems 14N1H-quadrupole dips have been observed. The conclusion is that amide groups are the dominating relaxation centers up to approx. 10(7) Hz. This finding can be understood by the fact that protein backbone fluctuations and, if possible, tumbling of the whole molecule rather than side group motions are the relevant mechanisms in this frequency range. A proton relaxation scheme for cells and tissue is presented.

Animals↗
PubMed1986

Deacylation of penicilloylated penicillin-binding proteins from Micrococcus luteus: kinetic study of thiol-promoted release of the bound penicilloyl moiety.

The stability of covalent complexes obtained by labelling penicillin-binding proteins 1-6 from Micrococcus luteus with a radioactive derivative of ampicillin has been examined in the presence of thiols. When the incubation medium contained only 1 mM 2-mercaptoethanol, the complexes were almost unaffected for at least 1 h. If 20 mM dithiothreitol was also included in the medium, the amount of bound radioactivity decreased throughout the incubation period. The breakdown of the complexes derived from penicillin-binding proteins 4 and 5 proceeded very slowly, following an apparent first-order kinetics, whereas the kinetics of deacylation of other penicillin-binding proteins exhibited a biphasic pattern with an initial fast phase followed by a slow one, each of which could be approximated by an apparent first-order reaction. This behavior is explained adequately by a two-step mechanism: the penicilloylated penicillin-binding proteins are first deacylated in a reversible exchange with the added thiol, giving rise to an intermediate thioester; once formed, this intermediate is hydrolysed irreversibly. A simple graphical method has been devised to deduce rate constants from the time course of the reaction. Theoretical curves have been constructed, and they fit experimental data satisfactorily. The results point out that added thiols may effectively interfere with the quantitation of penicillin-binding proteins; therefore, the stability of penicilloylated penicillin-binding proteins should be checked carefully when these protecting agents are included in membrane extracts or incubation media.

Ampicillin↗
PubMed1988

Purification of camel milk lysozyme and its lytic effect on Escherichia coli and Micrococcus lysodeikticus.

1. Camel milk lysozyme was purified using heparin-Sepharose 4B, Sephadex G-75 and hydroxyapatite chromatography. By this procedure lysozyme was separated from lactoferrin and a low molecular weight protein. 2. The lytic effect of camel milk lysozyme was assayed using Escherichia coli and Micrococcus lysodeikticus and its activity was compared with that of lysozyme from human milk and egg white. 3. The specific activity of camel milk lysozyme was found to be lower than that of lysozyme from human milk or from egg white. 4. Camel milk lactoferrin did not show a lytic effect on bacteria, while the low molecular weight protein showed lytic activity.

Animals↗
PubMed1990

The nucleotide sequence of an alpha-amylase gene from an alkalopsychrotrophic Micrococcus sp.

An alpha-amylase gene from Micrococcus sp. 207 was cloned into Escherichia coli JM101 using the vector pHSG399. The constructed recombinant plasmid pYK63 contained a 4.8 kb chromosomal DNA fragment derived from strain 207 DNA. The cloned amylase isolated from E. coli JM101 (pYK63) produced mainly maltotetraose from starch, and exhibited temperature and pH activity profiles closely similar to those of the enzyme from the original strain. Nucleotide sequence analysis of the cloned DNA fragment revealed one open reading frame containing the gene which consisted of 3312 bp (1104 amino acids). When compared with several other alpha-amylases, three consensus sequences were identified in the region of the active site. About 300 amino acid residues were present both upstream and downstream of the active site region.

Amino Acid Sequence↗
PubMed1981

New restriction endonucleases from Flavobacterium okeanokoites (FokI) and Micrococcus luteus (MluI).

Two new restriction endonucleases have been isolated from Flavobacterium okeanokoites IFO12536 and Micrococcus luteus IFO12992 and named FokI and MluI, respectively. Based on analysis of the sequences around the restriction sites, the recognition sequences and cleavage sites of these endonucleases were deduced as below: FokI: (formula: see text). MluI introduces double-strand cleavages at unique sequences that are completely two-fold rotationally symmetric like most type II restriction endonucleases. FokI belongs to a class of restriction endonucleases that recognize specific but asymmetric nucleotide sequences and introduce staggered cleavages at appointed positions away from the recognition sequences.

Bacterial Proteins↗
PubMed1986

Cloning of Micrococcus luteus 3-methyladenine-DNA glycosylase genes in Escherichia coli.

The 3-methyladenine-DNA glycosylase (m3ADG) excises 3-methyladenine (m3A) residues formed in DNA after treatment with alkylating agents. In Escherichia coli, the repair of this type of damage depends on the products of the genes tagA and/or alkA, which code for m3ADG I (20 kDa) and II (30 kDa), respectively. The tagA- and alkA--single mutants are sensitive to alkylating agents, the double mutant much more so. We have cloned two genes of Micrococcus luteus that can partly substitute the function of the E. coli tagA- and alkA- genes. An M. luteus genome bank was made by shotgun cloning of EcoRI + BamHI-digested DNA into pBR322. Two hybrid plasmids were identified that confer methylmethane sulfonate (MMS) resistance to the tagA- ada+ mutant and a capacity to reactivate MMS-treated bacteriophage lambda. Each hybrid plasmid directed the synthesis of 21-kDa m3ADG in E. coli tagA- ada-, which were not inhibited by 4 mM m3A. However, the restriction maps of the two cloned genes were different, and they showed no sequence homology as judged by the lack of cross hybridization.

Cloning, Molecular↗
PubMed1990

Structure of the dnaA region of Micrococcus luteus: conservation and variations among eubacteria.

A phylogenetic tree constructed by 5S rRNA analysis is composed of three major branches in eubacteria: high G + C Gram+, low G + C Gram+ and Gram- [Hori and Osawa, Mol. Biol. Evol. 4 (1987) 445-472]. We have shown that the characteristic dnaA region is common among Escherichia coli (Gram-), Pseudomonas putida (Gram-), and Bacillus subtilis (low G + C Gram+). We have now determined the structure of the dnaA region of Micrococcus luteus, as a representative of the last branch, high G + C Gram+. The dnaA gene and at least three other genes, rnpA, rpmH and dnaN were found to be conserved in M. luteus. Large nontranslatable regions were found flanking the dnaA gene. The upstream region is conserved in the four bacteria so far examined. On the other hand, the downstream region is conserved only in Gram+ bacteria, M. luteus and B. subtilis. The consensus sequence of the DnaA box in M. luteus seems to be TTGTCCACA, in contrast to TTATCCACA of other bacteria. These results confirm our hypothesis that the dnaA region is the replication origin of the ancestral bacteria and that the essential feature of the DnaA protein and DnaA-box combination is conserved in eubacteria.

Amino Acid Sequence↗
PubMed1992

UV endonuclease-mediated enhancement of UV survival in Micrococcus luteus: evidence revealed by deficiency in the Uvr homolog.

Unlike its phage T4 counterpart (also known as endonuclease V), Micrococcus luteus UV endonuclease (pyrimidine dimer DNA glycosylase/apurinic-apyrimidinic endonuclease) has suffered from lack of genetic evidence to implicate it in the promotion of UV survival of the cell, i.e., mutants with its deficiency are no more UV-sensitive than the wild type. On the assumption that the contribution of UV endonuclease is obscured by the presence of a homolog of Escherichia coli UvrABC endonuclease, which has recently been identified in this bacterium, survival studies were carried out in its absence. With 254-nm UV irradiation, which generates not only pyrimidine dimers but also 6-4 photoproducts as lethal lesions, a double mutant defective in both UV endonuclease and the Uvr homolog was shown to be more sensitive than a single mutant defective only in the latter, with a dose reduction factor of approximately 2 at the survival level of 37%. Furthermore, molecular photosensitization, which produces only pyrimidine dimers, revealed an even greater difference in sensitivity, the dose reduction factor being about 3.4. These results indicate that the contribution to cell survival of UV endonuclease, an enzyme specific for pyrimidine dimers, is manifest if the backup by the Uvr homolog is absent.

4-Nitroquinoline-1-oxide↗
PubMed2006

Crystal structure of a major fragment of the salt-tolerant glutaminase from Micrococcus luteus K-3.

Glutaminase of Micrococcus luteus K-3 (intact glutaminase; 48kDa) is digested to a C-terminally truncated fragment (glutaminase fragment; 42kDa) that shows higher salt tolerance than that of the intact glutaminase. The crystal structure of the glutaminase fragment was determined at 2.4A resolution using multiple-wavelength anomalous dispersion (MAD). The glutaminase fragment is composed of N-terminal and C-terminal domains, and a putative catalytic serine-lysine dyad (S64 and K67) is located in a cleft of the N-terminal domain. Mutations of the S64 or K67 residues abolished the enzyme activity. The N-terminal domain has abundant glutamic acid residues on its surface, which may explain its salt-tolerant mechanism. A diffraction analysis of the intact glutaminase crystals (a twinning fraction of 0.43) located the glutaminase fragment in the unit cell but failed to turn up clear densities for the missing C-terminal portion of the molecule.

Bacterial Proteins↗
PubMed2006

Resonance scattering spectra of micrococcus lysodeikticus and its application to assay of lysozyme activity.

BACKGROUND: Several methods, including turbidimetric and colorimetric methods, have been reported for the detection of lysozyme activity. However, there is no report about the resonance scattering spectral (RSS) assay, which is based on the catalytic effect of lysozyme on the hydrolysis of micrococcus lysodeikticus (ML) and its resonance scattering effect. METHODS RESULTS: ML has 5 resonance scattering peaks at 360 400, 420, 470, and 520 nm with the strongest one at 470 nm. The concentration of ML in the range of 2.0x10(6)-9.3x10(8) cells/ml is proportional to the RS intensity at 470 nm (I(470 nm)). A new catalytic RSS method has been proposed for 0.24-40.0 U/ml (or 0.012-2.0 mug/ml) lysozyme activity, with a detection limit (3sigma) of 0.014 U/ml (or 0.0007 microg/ml). Saliva samples were assayed by this method, and it is in agreement with the results of turbidimetric method. The slope, intercept and the correlation coefficient of the regression analysis of the 2 assays were 0.9665, -87.50, and 0.9973, respectively. CONCLUSION: The assay has high sensitivity and simplicity.

Bacteriolysis↗
PubMed2006

HSP70 gene expression in Mytilus galloprovincialis hemocytes is triggered by moderate heat shock and Vibrio anguillarum, but not by V. splendidus or Micrococcus lysodeikticus.

Complete sequence of HSP70 cDNA from the mussel, Mytilus galloprovincialis was established before quantifying its expression following moderate heat shock or injection of heat-killed bacteria. HSP70 cDNA is comprised of 2378 bp including one ORF of 654 aa, with a predicted 70 bp 5'-UTR and a 343 bp 3'-UTR (GenBank, 18 Jan 05, AY861684). Alignment identity ranged from 89% for Crassostrea ariakensis to 72% for C. virginica. Curiously, HSP70 gene and cDNA sequences from M. galloprovincialis, deposited later (03 and 27 May), show only 73% identity with the present sequence. Meanwhile, characteristic motifs of the HSP70 family were located in conserved positions. Expression of HSP70 gene was quantified on circulating hemocyte mRNA using Q-PCR after RT using random hexaprimers. Housekeeping gene was 28S rRNA. Four stresses were applied: heat shock that consisted of immersing mussels for 90 min at 30 degrees C and returning them to 20 degrees C sea water, one injection of heat-killed Gram-negative bacteria, Vibrio splendidus LGP32, one injection of heat-killed Gram-negative bacteria Vibrio anguillarum, one injection of heat-killed Gram-positive bacteria Micrococcus lysodeikticus. We found no significant modification of 28S rRNA gene expression. Significant increase of 5.2 +/- 0.4 fold the ratio HSP70/28S rRNA was observed 6 h after heat shock and was maximum at 15 h (6.1 +/- 1.1), and still significant after 24 h (1.7 +/- 0.03). Similarly, injecting V. anguillarum resulted in a significant increase of 2.7 +/- 0.1 after 12 h. Expression was maximum after 48 h (5.2 +/- 0.05) and returned to baseline after 72 h. In contrast, injecting V. splendidus or M. lysodeikticus failed to significantly modulate HSP70 gene expression at least during the first 3 days post-injection. Consequently, mussel hemocytes appeared to discriminate between pathogenic and non-pathogenic Vibrios, as well as between Gram-negative and Gram-positive bacteria.

Amino Acid Sequence↗
PubMed2006

Surface hydrolysis of polyacrylonitrile with nitrile hydrolysing enzymes from Micrococcus luteus BST20.

A new Micrococcus luteus strain BST20 was isolated with ability to metabolize PAN polymers as sole carbon source. Out of seven synthetized PAN copolymers containing different moieties of acrylic acid and/or vinyl acetate the polymer with lowest crystallinity (PAN with 5% vinyl acetate) was most easily metabolized. (13)C labelled PAN was completely converted to the acrylic acid by this strain. M. luteus BST20 produced membrane-bound nitrile hydrolysing enzymes able to convert nitrile groups on PAN powder surface to the corresponding acids. Similarly, nitrile groups on PAN fabrics were transformed to the corresponding acid as indicated by an K/S increased after dying with Methylene blue and the released ammonia. On small soluble substrates the enzyme system showed a preference for aliphatic and aromatic substituted aliphatic nitriles.

Acrylic Resins↗
PubMed1969

Passive electrical properties of microorganisms. IV. Studies of the protoplasts of Micrococcus lysodeikticus.

Observations of protoplasts of Micrococcus lysodeikticus show that removal of the cell wall of this organism decreases the dielectric constant by two orders of magnitude. The upper limit of the effective, homogeneous conductivity for the protoplast is 0.001 mho/m as compared with 0.045 mho/m for the intact cell. These results conclusively demonstrate the dominant effect of the cell wall on the low frequency dielectric properties of bacteria.

Cell Wall↗
PubMed1981

Evidence that dimers remaining in preinduced Escherichia coli B/r Hcr+ become insensitive after DNA replication to the extract from Micrococcus luteus.

In Escherichia coli B/r Her+ irradiated with two separate fluences, dimer excision is prematurely interrupted. The present study was designed to follow tha fate of dimers remaining unexcised. The results imply that these dimers (or distortions containing dimers) are transformed on replication from the state of sensitivity to the state of insensitivity to endonuclease from Micrococcus luteus. This conclusion is based on the following findings: (a) dimers were radiochromatographically detectable in DNA replicated after UV, which indicated that they were tolerated on replication. (b) Similar amounts of dimers were detected radiochromatographically both in DNA remaining unreplicated and DNA twice replicated after UV, This along with the low transfer of parental label into daughter DNA, indicated that dimers remained in situ in parental chains. (c) Immediately after UV, all parental DNA contained numerous sites sensitive to the extract from M. luteus. 2 h after UV, a portion of parental DNA still contained a number of endonuclease-sensitive (Es) sites, while another portion of parental DNA and all daughter DNA were free of Es sites. (d) The occurrence of parental DNA free of Es sites was not temporally correlated with dimer excision, but with the first round of DNA replication. (e) The amount of DNA free of Es sites corresponded to the amount of replicated DNA. (f) Separation of replicated and unreplicated DNA, and detection of Es sites in both portions separately showed that the replicated DNA was almost free of Es sites, whereas unreplicated DNA contained a number of such sites.

DNA Replication↗
PubMed1976

The chemical structure of a fragment of Micrococcus lysodeikticus cell-wall.

A fragment of Micrococcus lysodeikticus cell-wall obtained by cetylpyridinium recipitation from the nondialyzable portion of the degradation products of egg-white lysozyme was studied by the periodate oxidation and methylation procedures. The fragment consists of a polysaccharide chain composed of about 40 repeating (1 leads to 4)-O-(2-acetamido-2-deoxy-beta-D-mannopyranosyluronic acid)-(1 leads to 6)-O-(alpha-D-glucopyranosyl) residues with D-glucopyranosyl residues at both ends. The alpha-D-glucopyranose residue at the reducing end is linked to a phosphate group that is also linked to C-6 of a 2-acetamido-3-O-(D-1-carboxyethyl)-2-deoxy-beta-D-glucopyranosyl residue of a peptidoglycan chain composed of four repeating (1 leads to 4)-O-[2-acetamido-3-O-(D-1-carboxyethyl)-2-deoxy-beta-D-glucopyranosyl] residues. The peptidoglycan chain has, as nonreducing group, a 2-acetamido-2-deoxy-beta-D-glucopyranosyl group, and, as reducing residue, a 2-acetamido-3-O-(D-1-carboxytheyl)-2-deoxy-beta-D-glucose residue.

Amino Acids↗
PubMed1985

Prosthetic valve endocarditis due to methicillin-resistant Staphylococcus epidermidis and Micrococcus species successfully treated with rifampicin combined with other antibiotics.

Two patients with prosthetic valve endocarditis due to methicillin-resistant Gram-positive cocci (Staphylococcus epidermidis and Micrococcus spp.) are described. They were successfully treated with rifampicin combined first with an aminoglycoside and later with co-trimoxazole or co-trimoxazole plus vancomycin. The addition of rifampicin to these antibiotics resulted in enhanced serum bactericidal activity. High doses of rifampicin (1200-1800 mg) for 7-8 weeks did not cause any serious side-effect. Surgery was not required. During surveillance for more than 2 years endocarditis did not recur.

Adult↗
PubMed2000

Effects of combined exposure of micrococcus luteus to nisin and pulsed electric fields.

Death and injury following exposure of Micrococcus luteus to nisin and pulsed electric field (PEF) treatment were investigated in phosphate buffer (pH 6.8, sigma = 4.8 ms/cm at 20 degrees C). Four types of experiment were carried out, a single treatment with nisin (100 IU/ml at 20 degrees C for 2 h), a single PEF treatment, a PEF treatment followed by incubation with nisin (as before) and addition of nisin to the bacterial suspension prior to the PEF treatment. The application of nisin clearly enhanced the lethal effect of PEF treatment. The bactericidal effect of nisin reduced viable counts by 1.4 log10 units. Treatment with PEF (50 pulses at 33 kV/cm) resulted in a reduction of 2.4 log10 units. PEF treatment followed by nisin caused a reduction of 5.2 log10 units in comparison with a 4.9 log10 units reduction obtained with nisin followed by PEF. Injury of surviving cells was investigated using media with different concentrations of salt. Sublethally damaged cells of M. luteus could not be detected by this means, following PEF treatment.

Anti-Bacterial Agents↗