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S Tsunasawa

Publications and source records attributed to S Tsunasawa.

At least 55 records · Page 3Linked to original sources
PubMed1993

Microsequence analysis of the N-terminally blocked proteins immobilized on polyvinylidene difluoride membrane by western blotting.

A technique has been developed for efficient deblocking and subsequent microsequencing of N-terminally blocked proteins immobilized on a polyvinylidene difluoride (PVDF) membrane at the picomole levels. In this technique, proteins were first separated by polyacrylamide gel electrophoresis and then transferred onto a PVDF membrane by Western blotting. The electroblotted proteins with N-terminal acetylserine or acetylthreonine could be deblocked on-membrane by treatment with trifluoroacetic acid vapor and sequenced by a gas-phase protein sequencer. Similarly, N-formylated proteins could be deblocked on-membrane in HC1 solution and then directly sequenced from the N-terminal amino acid. Proteins with N-terminal pyroglutamic acid were enzymatically deblocked by in situ pyroglutamyl peptidase digestion, and N-acetylated proteins were also enzymatically deblocked with acylamino acid-releasing enzyme (AARE) after on-membrane digestion with trypsin to generate the N-terminal peptide fragment. This tryptic digestion was required since AARE can remove the acetylamino acid only from a short peptide. Based on these four deblocking methods, we present a strategy for sequential deblocking and subsequent N-terminal sequence analysis of N-blocked protein immobilized on PVDF membrane.

Acetylation↗
PubMed1993

Characterization of Geotrichum candidum lipase III with some preference for the inside ester bond of triglyceride.

A new form of Geotrichum candidum lipase with a unique positional specificity was found to exist in the culture broth as a minor component together with the well-documented major form. Unlike the major form, which cleaves both the inside and outside ester bonds of triglyceride indiscriminately, the newly isolated form showed some preference for the inside (2-position) ester bond. The new enzyme was also characterized by its own fatty acid specificity, i.e., an outstandingly high activity towards triolein and methyl oleate among the simple triglycerides and fatty acid methyl esters tested. Moreover, the enzyme possessed a specific activity three times as high as the major form. Notable difference in circular dichroism spectra were observed between the two forms, indicating distinct conformational differences. Edman degradation revealed that the N-terminal sequence of the new form differed from that of the major form, thus demonstrating the existence of a novel lipase gene on the chromosome.

Amino Acid Sequence↗
PubMed1992

NH2-terminal acetylation of ribosomal proteins of Saccharomyces cerevisiae.

Using a mutant of Saccharomyces cerevisiae defective in the NAT1 gene, that encodes one of the NH2-terminal acetyltransferases, we have identified 14 ribosomal proteins whose electrophoretic mobility at pH 5.0 suggests they carry an additional charge, presumably due to the lack of NH2-terminal acetylation. At least 30 other ribosomal proteins from the mutant are electrophoretically normal. Attempted NH2-terminal analysis of most of the presumed acetylated proteins from wild type cells indicated that all were blocked. NH2-terminal analysis of the same proteins from the nat1 mutant strain yielded unique sequences. Each one carries an NH2-terminal serine. We conclude that these are normally acetylated due to the presence of the NAT1 gene product. It seems surprising that cells whose ribosomes have been altered to this degree grow rather well and synthesize the same spectrum of proteins as do wild type cells (Mullen, J. R., Kayne, P. S., Moerschell, R. P., Tsunasawa, S. Gribskov, M., Sherman, F., and Sternglanz, R. (1989) EMBO J. 8, 2067-2075). Finally, this analysis has provided the first sequence information available for several of the acetylated ribosomal proteins and for one non-acetylated ribosomal protein, which is clearly the product of the MFT1 gene (Garrett, J. M., Singh, K. K., Vonder Haar, R. A., and Emr. S. D. (1991) Mol. Gen. Gen. 225, 483-491).

Acetylation↗
PubMed1992

Antibodies against 70-kD heat shock cognate protein inhibit mediated nuclear import of karyophilic proteins.

Previously, we found that anti-DDDED antibodies strongly inhibited in vivo nuclear transport of nuclear proteins and that these antibodies recognized a protein of 69 kD (p69) from rat liver nuclear envelopes that showed specific binding activities to the nuclear location sequences (NLSs) of nucleoplasmin and SV-40 large T-antigen. Here we identified this protein as the 70-kD heat shock cognate protein (hsc70) based on its mass, isoelectric point, cellular localization, and partial amino acid sequences. Competition studies indicated that the recombinant hsc70 expressed in Escherichia coli binds to transport competent SV-40 T-antigen NLS more strongly than to the point mutated transport incompetent mutant NLS. To investigate the possible involvement of hsc70 in nuclear transport, we examined the effect of anti-hsc70 rabbit antibodies on the nuclear accumulation of karyophilic proteins. When injected into the cytoplasm of tissue culture cells, anti-hsc70 strongly inhibited the nuclear import of nucleoplasmin, SV-40 T-antigen NLS bearing BSA and histone H1. In contrast, anti-hsc70 IgG did not prevent the diffusion of lysozyme or 17.4-kD FITC-dextran into the nuclei. After injection of these antibodies, cells continued RNA synthesis and were viable. These results indicate that hsc70 interacts with NLS-containing proteins in the cytoplasm before their nuclear import.

Amino Acid Sequence↗
PubMed1992

Deblocking and subsequent microsequence analysis of N alpha-blocked proteins electroblotted onto PVDF membrane.

A method was developed for direct microsequencing of N alpha-acetylated proteins electroblotted onto polyvinylidene difluoride membranes from polyacrylamide gels. N alpha-Acetylated proteins (greater than 32 pmol), including horse heart cytochrome c, five mutants of yeast cytochrome c, and bovine erythrocyte superoxide dismutase, were separated by SDS-PAGE and electroblotted onto polyvinylidene difluoride membranes. The portions of the membrane carrying the bands were cut out and treated with 0.5% polyvinylpyrrolidone in acetic acid solution at 37 degrees C for 30 min. The protein was digested on the membrane with 5-10 micrograms of trypsin at 37 degrees C for 24 h. During tryptic digestion, the resultant peptides were released from the membrane and the N-terminal peptide was efficiently deblocked with 50 mU of acylamino acid-releasing enzyme at 37 degrees C for 12 h. Picomole levels of the deblocked proteins could be sequenced directly by use of a gas-phase protein sequencer.

Acetylation↗
PubMed1992

Purification and characterization of a novel thermostable lipase from Pseudomonas cepacia.

A thermostable lipase from Pseudomonas cepacia has been purified to homogeneity as judged by SDS-PAGE and isoelectric focusing. The purification included treatment of the culture supernatant with acrinol, hydrophobic interaction chromatography, and gel filtration. The enzyme was a monomeric protein with M(r) of 36,500 and pI of 5.1. The optimal pH at 50 degrees C and optimal temperature at pH 6.5 were 5.5-6.5 and 55-60 degrees C, respectively, when olive oil was used as the substrate. Simple triglycerides of short and middle chain fatty acids (C < or = 12) were the preferred substrates over those of long chain fatty acids. The enzyme cleaved all the ester bonds of triolein, with some preference for the 1,3-ester bonds. The enzyme retained all its activity even after incubation at 75 degrees C (pH 6.5) for 30 min. Further, the activity was not impaired during 21 h storage at pH 6.5 in 40% water-miscible solvents including methanol, ethanol, acetone, acetonitrile, dimethylformamide, dimethylsulfoxide, and dioxane. The addition of dimethylsulfoxide or acetone to the assay mixture in the range of 0-35% stimulated the enzyme, whereas benzene or n-hexane had an inhibitory effect. These properties together with the N-terminal amino acid sequence confirmed that the enzyme differs from the known Pseudomonas sp. lipases.

Amino Acid Sequence↗
PubMed1992

The primary structure of porcine aminoacylase 1 deduced from cDNA sequence.

A cDNA encoding the complete amino acid sequence of aminoacylase 1 (N-acylamino acid aminohydrolase, ACY-1) [EC 3.5.1.14], a dimeric metalloprotein having two Zn2+ in the molecule, which catalyzes the deacylation of N-acylated L-amino acids except L-aspartic acid, has been isolated from porcine kidney lambda gt10 cDNA library and sequenced. From sequence analysis of the cDNA and the N- and C-terminal amino acid analyses of the purified protein, it is deduced that porcine kidney ACY-1 consists of two identical subunits (M(r) 45,260), each of which consists of a single chain of 406 amino acids with acetylalanine at the N-terminus. A cDNA encoding porcine liver ACY-1 was also cloned. The amino acid sequence deduced from the nucleotide sequence of the cDNA from porcine liver was identical to that deduced for porcine kidney ACY-1. Northern blot analysis suggested that ACY-1 is more highly expressed in kidney than in liver. Comparison of the amino acid sequence of porcine ACY-1 with those of other Zn2+-binding metalloenzymes showed no significant homologies in either the overall sequence or the consensus sequences for the metal binding sites. This indicates that ACY-1 is a new type of metalloprotein.

Amidohydrolases↗
PubMed1992

Identity of amino acid sequences of superoxide dismutase purified from both anaerobically maintained and aerated Porphyromonas gingivalis.

Superoxide dismutase (SOD) from anaerobically maintained Porphyromonas gingivalis (anaero-SOD) has the characteristic of Fe-SOD, whereas SOD from aerated cells (aero-SOD) has that of Mn-SOD. However, both types of apoSOD can bind either Fe or Mn. To elucidate the structure relationship between anaero- and aero-SOD, we examined the amino acid sequence of aero-SOD by direct protein analysis. The amino acid sequence of aero-SOD was shown to be identical with that of anaero-SOD determined previously. Our findings support the hypothesis that cambialistic SOD is formed from a single apoprotein in bacterial cells.

Aerobiosis↗
PubMed1992

Characterization of saccharide moiety in the electroplax sodium channel.

Carbohydrate chains on the large peptide of the voltage-sensitive sodium channel from Electrophorus electricus electroplax have been partially characterized by the lectin-blotting technique combined with digestion using three glucosidases: neuraminidase, endo-beta-N-acetylglucosaminidase H, and peptide: N-glycosidase F. The results show that both N-linked oligosaccharides and O-linked (mucin-type) oligosaccharides are present. In N-linked oligosaccharides, the results suggest the presence of complex- and hybrid-type oligosaccharides which contain bisecting N-acetylglucosamine(s), as well as the complex-type oligosaccharides with the alpha-Fuc-GlcNAc-(Asn) residue(s). In O-linked oligosaccharides, they must carry Gal beta1----3GalNAc- moieties which contain NeuNAc residues in the terminal.

Animals↗
PubMed1992

Inhibition of Achromobacter protease I by lysinal derivatives.

Z-Val-, Z-Pro-, Z-Leu-Leu-, and Z-Leu-Pro-lysinals and BZ-DL-lysinal were chemically synthesized and tested as novel inhibitors for Achromobacter protease I (API), a lysine-specific serine protease. Among the lysinal derivatives tested, Z-Val-lysinal was the most potent competitive inhibitor, its Ki being estimated as 6.5 nM in an esterolytic assay with Tos-Lys-OMe. In an amidolytic assay, Z-Leu-Leu-lysinal was the most potent inhibitor and the apparent mode of inhibition was non-competitive. The Kis of the other lysinal derivatives in both esterolytic and amidolytic assays were more than 10(3) times lower than that of leupeptin. Z-Val-lysinol, lacking the aldehyde group, was a poor competitive inhibitor. These results suggest that acyl-, acylaminoacyl-, and acylpeptidyllysinals function as a transition-state inhibitor for Achromobacter protease I.

Alcaligenes↗
PubMed1991

S-farnesylation and methyl esterification of C-terminal domain of yeast RAS2 protein prior to fatty acid acylation.

Posttranslational processing/modification is required for membrane localization and activation of ras proteins. In the case of yeast RAS2 protein, we have reported that the process starts with the removal of the initiator methionine followed by polyisoprenylation, removal of 3 amino acid residues from the C terminus, methyl esterification, and fatty acid acylation (Fujiyama, A., and Tamanoi, F. (1990) J. Biol. Chem. 265, 3362-3368). In this study, we demonstrate that polyisoprenylation and methyl esterification of the cysteine residue in the C-terminal domain of the RAS2 protein are involved in the conversion process from precursor form to intermediate form. The polyisoprenoid moiety attached to the RAS2 protein was identified as a 15-carbon farnesyl group through two independent experiments: the release of S-farnesylcysteine with carboxypeptidase Y from the RAS2 protein, and the recovery of radioactive farnesol through methyliodide treatment of the RAS2 protein purified from yeast cells labeled with [3H]mevalonic acid. The farnesyl group attached to the RAS2 protein was detected predominantly in the C-terminal peptide, SGSGGCC, both in the intermediate and in the fatty acid acylated RAS2 protein. The C-terminal cysteine of the intermediate protein is also modified by methyl esterification in a nearly stoichiometric manner.

Acylation↗
PubMed1991

Primary structure of nuclease P1 from Penicillium citrinum.

The primary structure of nuclease P1, which cleaves both RNA and single-stranded DNA, from Penicillium citrinum was elucidated. The complete amino acid sequence consisting of 270 residues was determined by analysis of peptides obtained by digestion with Achromobacter protease I of the reduced and S-aminoethylated protein and by digestion with Staphylococcus aureus V8 protease of the reduced and S-carboxymethylated protein. Four half-cystine residues were assigned to Cys72-Cys217 and Cys80-Cys85. N-Glycosylated asparagine residues were identified at positions 92, 138, 184 and 197. Fast-atom-bombardment and laser-ionization MS were successfully used to confirm the determined amino acid sequences of peptides and to estimate the molecular mass of this glycoprotein having heterogenous sugar moieties, respectively. Comparison of the amino acid sequence of nuclease P1 with other nucleases revealed that the protein has a high degree of sequence identity (50%) with nuclease S1 from Aspergillus oryzae. The His-Phe-Xaa-Asp-Ala sequence (positions 60-64) is similar to the sequence (His-Phe-Asp-Ala) involving the active-site His119 of bovine pancreatic RNase A, and the Pro-Leu-His sequence (positions 124-126) is identical with the sequence involving the active-site His134 of porcine pancreatic DNase I.

Amino Acid Sequence↗
PubMed1991

Synthesis and expression of genes encoding tuna, pigeon, and horse cytochromes c in the yeast Saccharomyces cerevisiae.

Genes encoding tuna, pigeon, and horse cytochromes c were constructed with synthetic oligodeoxyribonucleotides having preferred codons and portions of the iso-1-cytochrome c-encoding gene from the yeast Saccharomyces cerevisiae. The genes were ligated into an expression vector, which contains the normal 5'- and 3'-untranslated regions of the yeast iso-1-cytochrome c gene, and were integrated in single copy into the chromosome. Yeast strains were also constructed with multiple integrated copies of the pigeon gene. The heterologous and normal mRNA levels of the single-copy strains were equivalent. Although the N-terminal methionines were completely cleaved in the heterospecific proteins, the levels of trimethylation of Lys72 and acetylation of N-terminal glycines ranged from 39-78% and 10-70%, respectively. Horse cytochrome c was produced at a nearly normal level, whereas the pigeon and tuna cytochromes c were produced at approx. 40% of the normal levels. The levels of the cytochromes c and growth of the mutant yeast strains indicated that the heterospecific cytochromes c had approx. 50% specific activity in vivo.

Acetylation↗
PubMed1991

Amino acid sequence of nuclease S1 from Aspergillus oryzae.

The amino acid sequence of nuclease S1, a nuclease which cleaves both single-stranded DNA and RNA, from Aspergillus oryzae was determined. Reduced and S-carboxymethylated or S-aminoethylated nuclease S1 was digested with Achromobacter protease I, Staphylococcus aureus V8 protease, or endoproteinase Asp-N. Peptides thus obtained were purified by reverse-phase high-performance liquid chromatography and sequenced, and the complete primary structure was established. Nuclease S1 consists of a single peptide chain of 267 amino acid residues bearing N-glycosylated Asns 92 and 228. Five half-cystine residues are present at positions 25, 72, 80, 85, and 216, and the latter four residues are implicated in the formation of disulfide bonds by analogy with those in nuclease P1. Two short stretches of sequences involving His 60 and His 125 are shown to be identical with those involving active site His 119 in bovine ribonuclease A and active-site His 134 in porcine deoxyribonuclease I, respectively.

Amino Acid Sequence↗
PubMed1990

The specificities of yeast methionine aminopeptidase and acetylation of amino-terminal methionine in vivo. Processing of altered iso-1-cytochromes c created by oligonucleotide transformation.

The specificities of methionine aminopeptidase and amino-terminal acetylation in the yeast Saccharomyces cerevisiae were investigated in vivo by sequencing a series of altered iso-1-cytochrome c. Twenty iso-1-cytochromes c, each having a different penultimate residue in the sequence Met-Xaa-Phe-Leu-, were created by transforming yeast directly with synthetic oligonucleotides. The degree of methionine cleavage and amino-terminal acetylation was estimated from the levels of pertinent peptides separated by high performance liquid chromatography. The results confirmed our earlier hypothesis (Sherman, F., Stewart, J. W., and Tsunasawa, S. (1985) BioEssays 3, 27-31) that methionine is completely removed from penultimate residues having radii of gyration of 1.29 A or less (glycine, alanine, serine, cysteine, threonine, proline, and valine). However, only partial cleavage occurred in the sequences Met-Thr-Pro-Leu- and Met-Val-Pro-Leu-, demonstrating that proline at the third position inhibits methionine cleavage when the penultimate residue has an intermediate radius of gyration. Acetylation of the retained amino-terminal methionine occurred completely with the Ac-Met-Glu-Phe-Leu- and Ac-Met-Asp-Phe-Leu- sequences and partially with the Ac-Met-Asn-Phe-Leu-sequence. Although the consensus for acetylation of the retained amino-terminal methionine is not completely known, these results and the results of published sequences indicated that Ac-Met-Glu- and Ac-Met-Asp- (methionine followed by an acidic residue) is sufficient for amino-terminal acetylation in eukaryotes but not in prokaryotes.

Acetylation↗
PubMed1990

The primary structure of superoxide dismutase purified from anaerobically maintained Bacteroides gingivalis.

The superoxide dismutase (SOD) of Bacteroides gingivalis can use either iron or manganese as a cofactor in its catalytic activity. In this study, the complete amino acid sequence of this SOD purified from anaerobically maintained B. gingivalis cells was determined. The proteins consisted of 191 amino acid residues and had a molecular mass of 21,500. The sequence of B. gingivalis SOD showed 44-51% homology with those for iron-specific SODs (Fe-SODs) and 40-45% homology with manganese-specific SODs (Mn-SODs) from several bacteria. However, this sequence homology was considerably less than that seen among the Fe-SOD (65-74%) or Mn-SOD family (42-60%). This indicates that B. gingivalis SOD, which accepts either iron or manganese as metal cofactor, is a structural intermediate between the Fe-SOD and Mn-SOD families.

Amino Acid Sequence↗
PubMed1990

Localization of the covalent C3b-binding site on C4b within the complement classical pathway C5 convertase, C4b2a3b.

C5 convertase of the classical complement pathway is a trimolecular protein complex consisting of C4b, C2a, and C3b. In the complex there is an ester bond between C3b and C4b. We analyzed the C5 convertase formed on erythrocytes and localized the covalent binding site of C3b to a small region on C4b. The covalently linked C4b.C3b complex was purified from a detergent extract of the erythrocytes and digested with lysyl endopeptidase. An Mr 17,000 fragment containing the ester linkage between C4b and C3b was purified and its amino-terminal sequence was examined. Two amino acids were obtained at each cycle and identified with those in the sequences of C3 and C4. The sequence derived from C3 corresponded to the thioester region. The sequence derived from C4 started at Ala-1186. Alkali treatment of the fragment yielded an Mr 7,000 peptide derived from C4, which thus appeared to span the region of C4 from Ala-1186 to Lys-1259. Therefore, the covalent C3b-binding site on C4b is located within a 74-residue region of the primary structure. This finding supports the notion that after cleavage of C3 by the C4b2a complex, the covalent binding of metastable C3b to C4b is a specific reaction to form a trimolecular complex with a defined quaternary structure.

Amino Acid Sequence↗