scholarly journals Pteridine biosynthesis and nitric oxide synthase in Physarum polycephalum

1994 ◽  
Vol 304 (1) ◽  
pp. 105-111 ◽  
Author(s):  
G Werner-Felmayer ◽  
G Golderer ◽  
E R Werner ◽  
P Gröbner ◽  
H Wachter
Keyword(s):  
Nitric Oxide ◽  
Cell Cycle ◽  
Physarum Polycephalum ◽  
S Phase ◽  
Synchronous Cell ◽  
Cycle Dependent ◽  
Dihydroneopterin Aldolase ◽  
Oxide Synthase ◽  
Pteridine Biosynthesis ◽  
Aromatic Amino Acid Hydroxylases

Physarum polycephalum, an acellular slime mould, serves as a model system to study cell-cycle-dependent events since nuclear division is naturally synchronous. This organism was shown to release isoxanthopterin which is structurally related to tetrahydrobiopterin, a cofactor of aromatic amino acid hydroxylases and of nitric oxide synthases (NOSs) (EC 1.14.13.39). Here, we studied Physarum pteridine biosynthesis in more detail and found that high amounts of tetrahydrobiopterin are produced and NOS activity is expressed. Physarum pteridine biosynthesis is peculiar in as much as 7,8-dihydroneopterin aldolase (EC 4.1.2.25), an enzyme of folic acid biosynthesis usually not found in organisms producing tetrahydrobiopterin, is detected in parallel. NOS purified from Physarum depends on NADPH, tetrahydrobiopterin and flavins. Enzyme activity is independent of exogenous Ca2+ and is inhibited by arginine analogues. The purified enzyme (with a molecular mass of 130 kDa) contains tightly bound tetrahydrobiopterin and flavins. During the synchronous cell cycle of Physarum, pteridine biosynthesis increases during S-phase whereas NOS activity peaks during mitosis, drops at telophase and peaks again during early S-phase. Our results characterize Physarum pteridine biosynthesis and NOS and suggest a possible link between NOS activity and mitosis.

Biochemical and morphological characterization of the nuclear matrix during the synchronous cell cycle of Physarum polycephalum

1993 ◽  
Vol 105 (4) ◽  
pp. 1121-1130 ◽  
Author(s):  
S. Lang ◽  
T. Decristoforo ◽  
W. Waitz ◽  
P. Loidl
Keyword(s):  
Cell Cycle ◽  
Nuclear Matrix ◽  
Physarum Polycephalum ◽  
Nuclear Periphery ◽  
S Phase ◽  
Cycle Phase ◽  
Electron Microscopic ◽  
Nuclear Lamins ◽  
Synchronous Cell ◽  
Matrix Bound

We have investigated biochemical and ultrastructural aspects of the nuclear matrix during the naturally synchronous cell cycle of Physarum polycephalum. The morphology of the in situ nuclear matrix exhibited significant cell cycle changes as revealed by electron microscopic examination, especially during the progression of nuclei through mitosis and S-phase. In mitosis the interchromatin matrix was found to be retracted to the nuclear periphery; during S-phase this interchromatin matrix gradually resembled, concomitant with the reconstruction of a nucleolar remnant structure. During the G2-period no significant changes in matrix morphology were observed. The pattern of nuclear matrix proteins was invariant during the cell cycle; no cycle phase-specific proteins could be detected. In vivo labelling of plasmodia with [35S]methionine/cysteine showed that only a few proteins are synthesized and assembled into nuclear matrix structures in a cell cycle-dependent way; the majority of proteins were synthesized almost continuously. This was also shown for nuclear lamins homologues. In contrast to bulk nuclear histones, those histones that remain tightly bound to the nuclear matrix were synthesized and assembled into nuclear structures in the very first hour of S-phase; assembly was terminated in mid-S-phase, indicating that nuclear matrix-bound chromatin is replicated early in S-phase. Comparison of the acetylation pattern of matrix-bound histone H4 with bulk nuclear H4 revealed a largely elevated acetate content of matrix H4. The percentage of acetylated subspecies was entirely different from that in bulk nuclear H4, indicating that matrix-associated histones represent a subpopulation of nuclear histones with distinct properties, reflecting specific structural requirements of matrix-attached chromatin.

scholarly journals ADP-ribosyltransferase in isolated nuclei during the cell cycle of Physarum polycephalum

1985 ◽  
Vol 232 (1) ◽  
pp. 21-24 ◽  
Author(s):  
P Gröbner ◽  
P Loidl
Keyword(s):  
Cell Cycle ◽  
Physarum Polycephalum ◽  
S Phase ◽  
Exogenous Dna ◽  
Isolated Nuclei ◽  
Synchronous Cell ◽  
Enzyme Pattern ◽  
Adp Ribosyltransferase ◽  
Exogenous Substrates

ADP-ribosyltransferase was measured in isolated nuclei of Physarum polycephalum. Activity was determined with and without exogenous DNA and histones. During the synchronous cell cycle the activity measured with exogenous substrates exhibited a typical peak enzyme pattern with a maximum of activity in S-phase, whereas activity measured without exogenous substrates displayed a step enzyme pattern. Both activities doubled in each cell cycle.

scholarly journals Cell cycle–dependent localization of macroH2A in chromatin of the inactive X chromosome

2002 ◽  
Vol 157 (7) ◽  
pp. 1113-1123 ◽  
Author(s):  
Brian P. Chadwick ◽  
Huntington F. Willard
Keyword(s):  
Cell Cycle ◽  
X Chromosome ◽  
Degradation Pathway ◽  
S Phase ◽  
Histone H2a ◽  
The Core ◽  
Inactive X Chromosome ◽  
Inactivation Center ◽  
Chromatin Proteins ◽  
Cycle Dependent

One of several features acquired by chromatin of the inactive X chromosome (Xi) is enrichment for the core histone H2A variant macroH2A within a distinct nuclear structure referred to as a macrochromatin body (MCB). In addition to localizing to the MCB, macroH2A accumulates at a perinuclear structure centered at the centrosome. To better understand the association of macroH2A1 with the centrosome and the formation of an MCB, we investigated the distribution of macroH2A1 throughout the somatic cell cycle. Unlike Xi-specific RNA, which associates with the Xi throughout interphase, the appearance of an MCB is predominantly a feature of S phase. Although the MCB dissipates during late S phase and G2 before reforming in late G1, macroH2A1 remains associated during mitosis with specific regions of the Xi, including at the X inactivation center. This association yields a distinct macroH2A banding pattern that overlaps with the site of histone H3 lysine-4 methylation centered at the DXZ4 locus in Xq24. The centrosomal pool of macroH2A1 accumulates in the presence of an inhibitor of the 20S proteasome. Therefore, targeting of macroH2A1 to the centrosome is likely part of a degradation pathway, a mechanism common to a variety of other chromatin proteins.

scholarly journals Cell cycle dependent change in the endogenous phosphorylation of nucleolar proteins of Physarum polycephalum

FEBS Letters ◽  
1981 ◽  
Vol 124 (1) ◽  
pp. 53-56 ◽  
Author(s):  
Toshiko Shibayama ◽  
Shouzou Sawai ◽  
Kazuyasu Nakaya ◽  
Yasuharu Nakamura
Keyword(s):  
Cell Cycle ◽  
Physarum Polycephalum ◽  
Nucleolar Proteins ◽  
Dependent Change ◽  
Cycle Dependent

scholarly journals Enhancement of DNA-mediated gene transfer by high-Mr carrier DNA in synchronized CV-1 cells

1985 ◽  
Vol 225 (2) ◽  
pp. 529-533 ◽  
Author(s):  
A J Strain ◽  
W A H Wallace ◽  
A H Wyllie
Keyword(s):  
Cell Cycle ◽  
Gene Transfer ◽  
Transfection Efficiency ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
S Phase ◽  
Sv40 Virus ◽  
G2 Phase ◽  
Cycle Dependent ◽  
Sv40 Dna

Synchronized CV-1 cells were transfected with SV40 (simian virus 40) DNA-calcium phosphate co-precipitates. In the presence of carrier DNA, the transfection efficiency of SV40 DNA was decreased 5-fold in S-phase cells and was increased 4-fold in preparations of mitotically enriched cells as compared with asynchronous controls. No difference was observed when carrier DNA was omitted, when cells had progressed through S-phase and into G2-phase, or when the infectivity of cells to intact SV40 virus was tested. These results highlight the importance of cell-cycle-dependent factors on DNA-mediated gene transfer.

Arsenite-induced nitric oxide generation is cell cycle-dependent and aberrant in NBS cells

2003 ◽  
Vol 17 (2) ◽  
pp. 139-143 ◽  
Author(s):  
S.S. Yuan ◽  
M.F. Hou ◽  
H.L. Chang ◽  
T.F. Chan ◽  
Y.H. Wu ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Cell Cycle ◽  
Cycle Dependent

The SIT4 protein phosphatase functions in late G1 for progression into S phase

1991 ◽  
Vol 11 (4) ◽  
pp. 2133-2148
Author(s):  
A Sutton ◽  
D Immanuel ◽  
K T Arndt
Keyword(s):  
Cell Cycle ◽  
Protein Phosphatase ◽  
Catalytic Domain ◽  
Function Analysis ◽  
S Phase ◽  
Growth Defect ◽  
Temperature Sensitive ◽  
Amino Terminal ◽  
Polymorphic Gene ◽  
Cycle Dependent

Saccharomyces cerevisiae strains containing temperature-sensitive mutations in the SIT4 protein phosphatase arrest in late G1 at the nonpermissive temperature. Order-of-function analysis shows that SIT4 is required in late G1 for progression into S phase. While the levels of SIT4 do not change in the cell cycle, SIT4 associates with two high-molecular-weight phosphoproteins in a cell-cycle-dependent fashion. In addition, we have identified a polymorphic gene, SSD1, that in some versions can suppress the lethality due to a deletion of SIT4 and can also partially suppress the phenotypic defects due to a null mutation in BCY1. The SSD1 protein is implicated in G1 control and has a region of similarity to the dis3 protein of Schizosaccharomyces pombe. We have also identified a gene, PPH2alpha, that in high copy number can partially suppress the growth defect of sit4 strains. The PPH2 alpha gene encodes a predicted protein that is 80% identical to the catalytic domain of mammalian type 2A protein phosphatases but also has an acidic amino-terminal extension not present in other phosphatases.

Activation of the nitric oxide synthase pathway represents a key component of tumor necrosis factor–related apoptosis-inducing ligand–mediated cytotoxicity on hematologic malignancies

Blood ◽  
2001 ◽  
Vol 98 (7) ◽  
pp. 2220-2228 ◽  
Author(s):  
Paola Secchiero ◽  
Arianna Gonelli ◽  
Claudio Celeghini ◽  
Prisco Mirandola ◽  
Lia Guidotti ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Cell Cycle ◽  
Tumor Necrosis Factor ◽  
Nitric Oxide Synthase ◽  
Tumor Necrosis ◽  
K562 Cells ◽  
No Production ◽  
Effector Caspases ◽  
Oxide Synthase ◽  
Necrosis Factor

Tumor necrosis factor (TNF)–related apoptosis-inducing ligand (TRAIL) induced both cytotoxic (apoptosis) and cytostatic (cell cycle perturbation) effects on the human myeloid K562 cell line. TRAIL stimulated caspase 3 and nitric oxide synthase (NOS) activities, and both pathways cooperate in mediating inhibition of K562 survival/growth. This was demonstrated by the ability of z-VAD-fmk, a broad inhibitor of effector caspases, and N-nitro-l-arginine methyl ester (L-NAME), an NOS pharmacologic inhibitor, to completely (z-VAD-fmk) or partially (L-NAME) suppress the TRAIL-mediated inhibitory activity. Moreover, z-VAD-fmk was able to block TRAIL-mediated apoptosis and cell cycle abnormalities and increase of NOS activity. The addition of the NO donor sodium nitroprusside (SNP) to K562 cells reproduced the cytostatic effect of TRAIL without inducing apoptosis. When TRAIL was associated to SNP, a synergistic increase of apoptosis and inhibition of clonogenic activity was observed in K562 cells as well as in other myeloblastic (HEL, HL-60), lymphoblastic (Jurkat, SupT1), and multiple myeloma (RPMI 8226) cell lines. Although SNP greatly augmented TRAIL-mediated antileukemic activity also on primary leukemic blasts, normal erythroid and granulocytic cells were less sensitive to the cytotoxicity mediated by TRAIL with or without SNP. These data indicate that TRAIL promotes cytotoxicity in leukemic cells by activating effector caspases, which directly lead to apoptosis and stimulate NO production, which mediates cell cycle abnormalities. Both mechanisms seem to be essential for TRAIL-mediated cytotoxicity.

scholarly journals Molecular cloning and cell-cycle-dependent expression of the acetyl-CoA synthetase gene in Tetrahymena cells

1999 ◽  
Vol 343 (2) ◽  
pp. 479-485 ◽  
Author(s):  
Shulin WANG ◽  
Shigeru NAKASHIMA ◽  
Osamu NUMATA ◽  
Kenta FUJIU ◽  
Yoshinori NOZAWA
Keyword(s):  
Heat Treatment ◽  
Cell Cycle ◽  
Cell Division ◽  
Amino Acid ◽  
Mrna Expression ◽  
Mrna Level ◽  
Cyclic Heat Treatment ◽  
Acetyl Coa ◽  
Synchronous Cell ◽  
Cycle Dependent

To identify transcriptionally regulated mediators associated with the cell cycle, we adopted the differential mRNA display technique for cell cultures of Tetrahymenapyriformis synchronized by cyclic heat treatment. One cDNA fragment that was expressed differently during synchronous cell division had a greatly decreased expression at 30 min after the end of heat treatment (EHT). Using this fragment as a probe, we isolated the full-length cDNA for T. pyriformis acetyl-CoA synthetase (TpAcs) which encodes a 651 amino acid polypeptide with a predicted molecular mass of 72.8 kDa. The deduced amino acid sequence of T. pyriformis ACS shows 42% sequence identity compared with that ofLysobacter sp. acetyl-CoA synthetase (ACS), an enzyme which catalyses the formation of acetyl-CoA from acetate via an acetyl-adenylate intermediate. The deduced sequence is also 41% and 40% identical compared with those of Pseudomonas putida and Coprinus cinereus ACS, respectively. The deduced sequence of T. pyriformis ACS also shares similar characteristics of the conserved motifs I and II in the ACS family. To further investigate the actions of the gene encoding this enzyme, mRNA expression was determined during the course of synchronized cell division in T. pyriformis. Northern blot results show that the mRNA level was dramatically decreased at 30 min after EHT prior to entering synchronous cell division (which occurs 75 min after EHT), suggesting that mRNA expression of the TpAcs was associated with the cell cycle and that the down-regulated expression of TpAcs at 30 min after EHT would be required for the initiation of the oncoming synchronous cell division in T. pyriformis.

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