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71.
Masaki Sugiura Tsutomu Takagi Masahiko Kisumi 《Applied microbiology and biotechnology》1985,21(3-4):213-219
Summary Proline-producing strains of Serratia marcescens Sr41 were constructed by three rounds of mutagenesis. A strain SP103 which did not degrade l-proline carried the putA mutation leading to lack of proline oxidase. A 3,4-dehydroproline-resistant mutant SP105, derived from strain SP103, carried the dpr-1 mutation which resulted in desensitization of the feedback inhibition of glutamate kinase. Strain SP103 produced 5.5 mg of l-proline per ml of fermentation medium containing sucrose and urea. Growth inhibition by proline analogs was enhanced when succinate was used as a carbon source in the medium. A thiazolidine-4-carboxylate-resistant mutant SP126 derived from strain SP105 produced 20.5 mg of l-proline per ml of medium. The mutation carried by strain SP126 might be distant from dpr-1 and putA mutations on the chromosome. Pyrroline-5-carboxylate reductase was not repressed by proline in S. marcescens Sr41. 相似文献
72.
Mg2+-dependent unwinding of DNA by nonhistone chromosomal protein HMG(1 + 2) from pig thymus as determined by DNA melting temperature analysis 总被引:2,自引:0,他引:2
In the previous studies with endonucleases specific for single-stranded DNA, we have indicated that the nonhistone chromosomal protein HMG(1 + 2) prepared from pig thymus has an activity to unwind DNA partially at low protein-to-DNA weight ratios (Yoshida, M. & Shimura, K. (1984) J. Biochem. 95, 117-124). In the present work, we have pursued the unwinding reaction by HMG(1 + 2) by thermal melting temperature analysis of DNA, and by investigating the effect of Mg2+ on the reaction. The melting temperature of DNA in the presence of HMG(1 + 2) at low protein weight ratios decreased in 2 mM Tris-HCl, pH 7.8, whereas it increased at higher ratios. The depressions of melting temperature by HMG(1 + 2) at low ratios were not observed either in the system of 2 mM Tris-HCl, pH 7.8, containing EDTA or in the system containing samples treated in advance with EDTA. An addition of Mg2+ to the system reproduced the depression of melting temperature at low protein-to-DNA ratios as well as the increase at higher ratios. Analysis by Mg2+-equilibrated gel filtration revealed that HMG(1 + 2) is a Mg2+-binding protein. However, the depression of melting temperature at low protein-to-DNA ratios was not due to removal of Mg2+ from DNA by HMG(1 + 2). From these results, it is concluded that HMG(1 + 2) causes a partial DNA unwinding detectable by thermal melting temperature analysis of DNA, and that Mg2+ is necessary for the unwinding reaction. 相似文献
73.
Differential expression and distribution of chicken skeletal- and smooth-muscle-type alpha-actinins during myogenesis in culture 总被引:13,自引:11,他引:2 下载免费PDF全文
Antibodies to chicken fast skeletal muscle (pectoralis) alpha-actinin and to smooth muscle (gizzard) alpha-actinin were absorbed with opposite antigens by affinity chromatography, and four antibody fractions were thus obtained: common antibodies reactive with both pectoralis and gizzard alpha-actinins ([C]anti-P alpha-An and [C]anti-G alpha-An), antibody specifically reactive with pectoralis alpha-actinin ([S]anti-P alpha-An), and antibody specifically reactive with gizzard alpha-actinin ([S]anti-G alpha-An). In indirect immunofluorescence microscopy, (C)anti-P alpha-An, (S)anti-P alpha-An, and (C)anti-G alpha- An stained Z bands of skeletal muscle myofibrils, whereas (S)anti-G alpha-An did not. Although (S)anti-G alpha-An and two common antibodies stained smooth muscle cells, (S)anti-P alpha-An did not. We used (S)anti-P alpha-An and (S)anti-G alpha-An for immunofluorescence microscopy to investigate the expression and distribution of skeletal- and smooth-muscle-type alpha-actinins during myogenesis of cultured skeletal muscle cells. Skeletal-muscle-type alpha-actinin was found to be absent from myogenic cells before fusion but present in them after fusion, restricted to Z bodies or Z bands. Smooth-muscle-type alpha- actinin was present diffusely in the cytoplasm and on membrane- associated structures of mononucleated and fused myoblasts, and then confined to membrane-associated structures of myotubes. Immunoblotting and peptide mapping by limited proteolysis support the above results that skeletal-muscle-type alpha-actinin appears at the onset of fusion and that smooth-muscle-type alpha-actinin persists throughout the myogenesis. These results indicate (a) that the timing of expression of skeletal-muscle-type alpha-actinin is under regulation coordination with other major skeletal muscle proteins; (b) that, with respect to expression and distribution, skeletal-muscle-type alpha-actinin is closely related to alpha-actin, whereas smooth-muscle-type alpha- actinin is to gamma- and beta-actins; and (c) that skeletal- and smooth- muscle-type alpha-actinins have complementary distribution and do not co-exist in situ. 相似文献
74.
Summary When the red-light grown protonema ofAdiantum capillus-veneris was transferred to the dark, the nucleus ceased its migration ca. 5 hours before cell plate formation (Mineyuki andFuruya 1980). To see whether the nucleus was held by some cytoplasmic structure during nuclear positioning, protonemata were treated with various centrifugal forces at different stages of the cell cycle. Nuclei of G1 phase were easily displaced by centrifugation at 360×g for 15 minutes, but those of G2 or M phase were not displaced by it, suggesting that the nuclei were held by some cytoplasmic elements in G2 or M phase. This nuclear anchoring was not detectable in protonemata that were treated with 5mM colchicine. With this treatment, the nucleus did not stop its migration at late G2 and moved even in prophase. And the retardation of organelle movement which was observed in cytoplasm on the lateral side of the nucleus after the cessation of premitotic nuclear migration (Mineyuki andFuruya 1984) was not observed in the presence of colchicine. Thus the nuclei appear to be held by colchicine-sensitive structure in cytoplasm between the lateral surface of the nucleus and cell wall during the premitotic nuclear positioning. Electron micrographs showing cytoplasmic microtubules were consistent with the idea.Abbreviations PPN
Premitotic positioning of the nucleus
- L region
Cytoplasm between the lateral surface of the nucleus and cell wall (seeMineyuki
et al. 1984) 相似文献
75.
Isolation and Characterization of Tonoplast from Chilling-Sensitive Etiolated Seedlings of Vigna radiata L 总被引:2,自引:0,他引:2 下载免费PDF全文
Tonoplasts were isolated in a high purity from etiolated young seedlings of Vigna radiata L. (mung bean) utilizing a sucrose density gradient system. The excised hypocotyls were homogenized in a sorbitol-buffer system and the 3,600 to 156,000g pellets obtained after the differential centrifugations were suspended in a sorbitol medium and loaded on a linear sucrose density gradient. After centrifugation at 89,000g for 2 hours, tonoplasts were banded at the sample load/sucrose interface. Assessed by electron microscopy and marker enzymes, the purity and the quantity were found to be sufficient for biochemical and biophysical analyses. The tonoplasts were associated with NO3−-sensitive and vana-date-insensitive ATPase. The tonoplast ATPase was stimulated by proton ionophores such as carbonyl cyanide p-trifluoromethoxyphenyl-hydrazone and gramicidin D, suggesting a proton-pumping enzyme. In the presence of ATP and Mg2+, a proton gradient was formed in the isolated tonoplast vesicles as assessed by fluorescence quenching of quinacrine. The tonoplasts contained several kinds of mannosylated or glycosylated glycoproteins and a major protein (65 kilodaltons) which was unique to the membranes. 相似文献
76.
77.
Structure, expression, and chromosomal location of the human c-fgr gene. 总被引:22,自引:11,他引:11 下载免费PDF全文
M Nishizawa K Semba M C Yoshida T Yamamoto M Sasaki K Toyoshima 《Molecular and cellular biology》1986,6(2):511-517
78.
8-Bromoguanosine 2'- and 3'-phosphates have been shown to bind to RNase T1 with the same affinity as the corresponding guanosine phosphates, inducing difference absorption and circular dichroism spectra similar to those induced by the guanosine phosphates. Since the brominated ligands have reduced electron density on N-7 of the guanine ring and syn-fixed conformation due to a bulky, electron-withdrawing Br substituent on C-8, the difference spectra are not attributable to the protonation on N-7 and to the restriction of the ligand to syn-conformation as proposed previously. 相似文献
79.
ATPase inhibitor protein, which blocks mitochondrial ATPase activity by forming an enzyme-inhibitor complex, was found to be synthesized as a larger precursor in a cell-free translation system directed by yeast mRNA. Other protein factors, which stabilize latent ATPase by binding to the enzyme-inhibitor complex, were also found to be formed as larger precursors. The precursor of ATPase inhibitor protein was transported into isolated yeast mitochondria and was cleaved to the mature peptide in the mitochondria. Impaired mitochondria lacking phosphorylation activity could not convert the precursor to the mature form. Neither antimycin A nor oligomycin alone exhibited a marked effect on the transport-processing of the precursor by intact mitochondria. However, when antimycin A was added with oligomycin, the transport-processing was markedly inhibited. The processing was also strongly inhibited by an uncoupler, carbonylcyanide p-trifluoro-methoxyphenyl hydrazone. The inhibition by the uncoupler was not relieved by ATP added externally. It is concluded that the transport-processing of precursor proteins requires intact mitochondria with a potential difference across the inner membrane. 相似文献
80.
R Hille T Yoshida G E Tarr C H Williams M L Ludwig J A Fee T A Kent B H Huynh E Münck 《The Journal of biological chemistry》1983,258(21):13008-13013
The soluble ferredoxin from Thermus thermophilus was examined by M?ssbauer and EPR spectroscopies and by reductive titrations. These studies demonstrate the presence of one 3Fe center, responsible for the characteristic g = 2.02 EPR signal in the oxidized protein, and one [4Fe-4S] center which is responsible for the rhombic EPR spectrum of the fully reduced protein. These assignments should replace those made by Ohnishi et al. (Ohnishi, T., Blum, H., Sato, S., Nakazawa, K., Hon-nami, K., and Oshima, T. (1980) J. Biol. Chem. 255, 345-348) prior to the discovery of the 3Fe clusters. The amino acid composition was determined and is discussed with reference to recent structural studies of 7Fe ferredoxins. 相似文献