In addition to the ARS core, the ARS box is necessary for autonomously replicating sequences

Summary Autonomously replicating sequences (ARSs) were cloned from nuclear and mitochondrial DNA of D. melanogaster using YIp5, which is composed of pBR322 and the yeast ura3 gene, as the cloning vector and YNN27, a Ura^- yeast strain as the recipient. The nucleotide sequences of six ARSs, two from nuclear bulk, two from the nuclear 1.688 satellite, and two from mitochondorial DNA, were determined. The relationship between the transformation frequency and the inclusion of the ARS core, 5 _T ^A TT-TAT _A ^G TTT _T ^A 3, of these fragments was analysed. All the ARSs contained an ARS core or a single base change of it. However, not all the fragments that contained a single base change of the ARS core were able to transform the recipient cells, suggesting that certain bases in the ARS core were not exchangeable. It is suggested by transformation experiments with subfragments that in addition to an ARS core, an ARS box which is located within 25 bp upstream of the ARS core and whose sequence is composed of 5TNT _G ^A AA 3, is necessary for autonomous replication.     

cDNA cloning of an mRNA encoding a sulfur-rich 10 kDa prolamin polypeptide in rice seeds

Using a rice maturing seed pUC9 expression library, we isolated a cDNA clone corresponding to 10 kDa sulfurrich prolamin by immunoscreening. A longer cDNA clone was obtained from a gtll library by plaque hybridization using this ³²P-labeled cDNA as a probe. A polypeptide sequence composed of 134 amino acids was deduced from the nucleotide sequence. A 24 amino acid signal peptide was assigned by computer calculation for the membrane spanning region and Edman sequencing of the purified mature polypeptide. Remarkably, 20% of methionine and 10% of cysteine were found in the mature polypeptide as well as high contents of glutamine, and hydrophobic amino acids. Part of the amino acid sequence was homologous with a conserved cysteine-rich region found in other plant prolamins. Two repeats of amino acid sequence were found in the polypeptide.     

Localization of the regulatory subunit of cAMP-dependent protein kinase in Saccharomyces cerevisiae

The subcellular distribution of the regulatory subunit of cAMP-dependent protein kinase in Saccharomyces cerevisiae cells was determined by subcellular fractionation and indirect immunofluorescence microscopy using the bcy1 mutant deficient in the regulatory subunit as control. The regulatory subunit of cAMP-dependent protein kinase showing cAMP-binding activity was identified as a single protein of 50 kDa by photoaffinity labeling and immunoblotting. The regulatory subunit was concentrated in a nuclear fraction in addition to a cytoplasmic fraction. By comparison of the regulatory subunit distribution with the DNA localization, the area detected by the indirect immunofluorescence was identified as the nucleus.     

Purification and properties of mitochondrial malate dehydrogenase from unfertilized eggs of the sea urchin, Anthocidaris crassispina

Purification and characterization of mitochondrial malate dehydrogenase [EC 1.1.1.37] from unfertilized eggs of the sea urchin, Anthocidaris crassispina, are described. The purification method consisted of dextran sulfate fractionation, Blue Dextran Sepharose chromatography, Phenyl-Sepharose hydrophobic chromatography and DEAE-cellulose chromatography. The enzyme was purified 771-fold with a 7% yield from the crude extract. The purified enzyme appeared homogeneous on polyacrylamide gel electrophoresis under both native and denatured conditions. After incubation at 45 degrees C for 50 min, the enzyme lost about 90% of its activity. In the presence of NADH, however, the enzyme was protected against the heat denaturation. The native enzyme had a molecular weight of about 65,000 and probably consisted of two identical subunits. In the reduction of oxaloacetate with NADH, a broad optimum pH ranging from 8.2 to 9.4 was found with 50 mM Tris-HCl and glycine-NaOH buffers. Sodium phosphate buffer apparently activated the enzyme. The apparent Km values for oxaloacetate and NADH were 19 microM and 30 microM, respectively. The optimum pH for malate oxidation with NAD+ was 10.2 in 50 mM NaHCO3-Na2CO3 buffer. The apparent Km values for malate and NAD+ were 7.0 mM and 0.6 mM, respectively. Zinc ion, sulfite ion, p-chloromercuriphenylsulfonate and adenine nucleotides strongly inhibited the enzyme.     

Influence of phospholipase treatments on ligand bindings to a benzodiazepine receptor-GABA receptor-chloride ionophore complex

Treatment of rat cerebellar membranes with phospholipase A2 (PLA2) or phospholipase C (PLC) increased basal [3H]diazepam binding at 0 degrees C with concomitant disappearance of the stimulatory effect of Cl- ion on the binding. On the other hand, these treatments did not affect the stimulatory effect of GABA, nor the maximum enhancement obtained in the presence of both GABA and Cl- ion. These results suggest that PLA2 or PLC modified the phospholipids responsible for the interaction between the benzodiazepine receptor and the Cl- ionophore. This assumption was supported by the results of thermodynamic experiments which showed that the changes in thermodynamic parameters occurring after the addition of Cl- ion resembled those after PLA2 or PLC treatment. Since the effect of PLA2 was evident at very low concentrations, and a PLC concentration of at least one order of magnitude higher was required to induce a similar effect, the change of phospholipids especially to lysophospholipids seems to be of particular importance. Protein release from the membrane, which also occurs after PLA2 or PLC treatment, did not appear to be responsible for the present phenomenon.     

Surface-Bound Nuclease of Staphylococcus aureus: Localization of the Enzyme

The cellular localization of staphylococcus nuclease, previously known as an exoenzyme, was investigated, and the following results were obtained. (i) When Staphylococcus aureus cells were converted to protoplasts by cell wall lytic enzyme L-11 (a bacteriolytic enzyme purified from Flavobacterium sp. which specifically hydrolyzes amide and peptide linkages of murein layers), over 80% of the cell-bound nuclease was released into the surrounding sucrose medium. (ii) The cell-bound nuclease was associated with the cell-wall membrane fraction of mechanically disrupted cells. (iii) The nuclease activity of cell-wall membrane fractions from cells during early and late stages of protoplast formation were compared. Less activity was found in the late stage. These results suggest that nuclease may be located at or near the surface of the cells. The distribution of cell-bound nuclease in the cell-wall membrane fraction varied with the growth conditions of S. aureus. The activity of alkaline phosphatase, another surface enzyme, was also investigated. Less of this enzyme than nuclease was released when the cells were converted to protoplasts.     

Surface-Bound Nuclease of Staphylococcus aureus: Purification and Properties of the Enzyme

The surface-bound nuclease of Staphylococcus aureus liberated during formation of protoplasts was purified 1,000-fold by chromatography on phosphocellulose. Its properties were compared with those of the known extracellular nuclease, purified 200-fold by the same procedures. The adsorbance of the surface-bound nuclease on phosphocellulose was distinctly different from that of the extracellular nuclease, but other properties of the two enzymes were similar. Both enzymes had a pH optimum of about 10 and required Ca²⁺ for activity. Both enzymes hydrolyzed deoxyribonucleic acid (DNA) and ribonucleic acid, and denatured DNA was a better substrate than native DNA. Both enzymes were inhibited by the same metal ions. Nuclease-less mutants of S. aureus were isolated from S. aureus 209P by using N-methyl-N′-nitroso-N-nitrosoguanidine. These mutants contained neither surface-bound nor extracellular nuclease activity. These results suggest that the surface-bound and extracellular nucleases are expressed from the same cistron of S. aureus.     

Lipopolysaccharides of Escherichia coli K12 Strains That Express Cloned Genes for the Ogawa and Inaba Antigens of Vibrio cholerae O1: Identification of O-Antigenic Factors

Structural and serological studies were performed with the lipopolysaccharide (LPS) expressed by Escherichia coli K12 strains No. 30 and No. 64, into which cosmid clones derived from Vibrio cholerae O1 NIH 41 (Ogawa) and NIH 35A3 (Inaba) had been introduced, respectively. The two recombinant strains, No. 30 (Ogawa) and No. 64 (Inaba), produced LPS that included, in common, the O-polysaccharide chain composed of an α(1 → 2)-linked N-(3-deoxy-L -glycero-tetronyl)-D -perosamine (4-amino-4,6-dideoxy-D -manno-pyranose) homopolymer attached to the core oligosaccharide of the LPS of E. coli K12. Structural analysis revealed the presence of N-(3-deoxy-L -glycero-tetronyl)-2-O-methyl-D -perosamine at the non-reducing terminus of the O-polysaccharide chain of LPS from No. 30 (Ogawa) but not from No. 64 (Inaba). Serological analysis revealed that No. 30 (Ogawa) and No. 64 (Inaba) LPS were found to share the group antigen factor A of V. cholerae O1. They were distinguished by presence of the Ogawa antigen factor B [co-existing with relatively small amounts of the Inaba antigen factor (c)] in the former LPS and the Inaba antigen factor C in the latter LPS. It appears, therefore, that No. 30 (Ogawa) and No. 64 (Inaba) have O-antigenic structures that are fully consistent with the AB(c) structure for the Ogawa and the AC structure for the Inaba O-forms of V. cholerae O1, respectively. Thus, the present study clearly confirmed our previous finding that the Ogawa antigenic factor B is substantially related to the 2-O-methyl group at the non-reducing terminus of the α(1 → 2)-linked N-(3-deoxy-L -glycero-tetronyl)-D -perosamine homopolymer that forms the O-polysaccharide chain of LPS of V. cholerae O1 (Ogawa).