The properties of the recB and recC gene products of Escherichia coli were studied using recB and recC gene-inserted plasmids. recB mutants and recC mutants lacked ATP-dependent DNase (recBC enzyme) but showed apparent recovery of enzyme activity on introduction of plasmids carrying the recB and recC gene, respectively. The ATP-dependent DNase was also constructed in vitro by mixing the recB and recC gene products encoded by the plasmids with the corresponding gene. Specific labeling of plasmid-encoded proteins by the maxicell method showed that the recB and recC gene products were 135,000 and 125,000 dalton proteins, respectively. These results suggest that the recB and recC genes are the structural genes of the beta and alpha subunits, respectively, of the recBC enzyme. A gene that encodes a protein of about 100,000 daltons was found to be located between the recB and recC genes. But the product of this gene was shown not to be included in the recBC enzyme.

DNA Restriction Enzymes↗

PubMed1983

Chiral synthesis of asymmetrically tetra-C-substituted cyclopentane derivatives by Diels-Alder addition of cyclopentadiene to unsaturated acyclic-sugar derivatives.

Optically pure, substituted cyclopentane derivatives of interest in synthesis of prostaglandin analogs have been obtained by stereocontrolled addition of cyclopentadiene to trans alpha,beta-unsaturated sugar derivatives. Methyl (E)-4,5,6,7-tetra-O-acetyl-2,3-dideoxy-D-arabino-hept-2-enonate (2), obtained by Wittig addition of Ph3PCHCO2Me to aldehydo-D-arabinose tetraacetate, reacted with cyclopentadiene in boiling toluene to give 40% of a crystalline, norbornene adduct (3) having the 5S-exo ester, 6S-endo sugar-chain configuration, as established by crystallography and by conversions into the known, crystalline (2S,3S)-bis(p-tolylsulfonyloxymethyl)bicyclo[2.2.1]heptane. Likewise, the L enantiomer (19) of 2 was converted into the crystalline enantiomer of 3; chromatographic resolution of the other Diels-Alder adducts from the reaction afforded lesser amounts of the other three possible isomeric adducts, which were characterized by appropriate conversions. The Ph3PCHCO2Me Wittig adduct (9) from 2,3:4,5-di-O-isopropylidene-aldehydo-D-arabinose with cyclopentadiene in hot toluene gave a crystalline mixture of the isomeric 5S,6S adducts (10 and 11), separable after deacetonation and acetylation as the already characterized product 3 and its 6S-endo ester, 5S-exo sugar-chain isomer. Likewise, the L enantiomer of the D dienophile 9 gave a crystalline mixture of 5R,6R adducts that were the enantiomers of 10 and 11. A reversed ratio of adducts resulted when the tetraacetylated L dienophile 19 reacted at 0 degrees with cyclopentadiene under AlCl3 catalysis, and 36% of the crystalline 5S-endo ester, 6S-exo sugar-chain adduct (23) was obtained. Hydroxylation-glycol cleavage of the double bond in 23, followed by reduction and acetylation, gave 65% of an optically pure cyclopentane derivative having five chiral centers of the same absolute configuration as in prostaglandin F1 alpha.

Carbohydrates↗

PubMed1983

A frameshift addition causes silencing of the delta-globin gene in an old world monkey, an anubis (Papio doguera).

A delta-globin gene of an anubis, Papio doguera, was cloned, and the nucleotide sequence of a region of about 2,000 bp including the gene was determined. In comparison with that of pSP3, a delta-globin clone from the gene library of a normal Japanese, the anubis delta-globin gene showed one base addition in the second exon at the codon for amino acid 55, generating a termination codon at the new 59th codon. The other differences found in the region analyzed were not considered to affect expression of the delta-globin gene. Therefore, it was concluded that this frameshift addition was at least one of the causes of silencing of the delta-globin gene in the anubis. In addition, from the sequence divergence in the delta-globin gene, the period of this silencing was estimated to be at most 4 million years, and the divergence of anubis occurred at most 30 million years ago.

Animals↗

PubMed1983

Structural analysis of a beta-thalassemia gene found in Taiwan.

The beta-globin gene from a patient with homozygous beta-thalassemia in Taiwan was cloned and extensively sequenced. Four nucleotides in the codon for amino acids, 41 and 42, are deleted. This change generates a frame-shift mutation and a termination codon in the new 59th codon. Some changes in nucleotide sequence were also found in intervening sequences IVS1 and IVS2, and Exon3, and were considered to be sequence polymorphisms.

Amino Acid Sequence↗

PubMed1983

Construction of a lambda packageable ColE1 vector which permits cloning of large DNA fragments: cloning of thyA gene of Escherichia coli.

A small packageable plasmid depending on the ColE1 replicon was constructed from ColE1-gal-cos lambda:: Tn3, pKY2113 (T. Nakamura et al. (1981) J. Biochem. 90, 1013), and named pKY2662. This plasmid carries ampicillin resistance and colicin E1 immunity genes as selective markers, and has neither mobilization function nor movable transposon. The molecular size of pKY2662 is 8.7 kb, and it has a single cleavage site each for BamHI, Bg/II, ClaI, EcoRI, HpaI, PstI, and Tth111I. By using pKY2662 as a vector, a 32 kb Escherichia coli DNA fragment covering thyA, recC, recB, and argA genes was cloned. This new small cosmid is among the most efficient vectors hitherto found for in vitro cloning of large DNA fragments.

Bacteriophage lambda↗

PubMed1983

Studies of cell and organ culture of psoriatic and normal epidermis in vitro.

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Adult↗

PubMed1983

Cysteamine rapidly decreases mitotic cells in random culture of HeLa S-3 cells.

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Cysteamine↗

PubMed1983

[Coronary ostial stenosis due to aortitis syndrome (Takayasu's arteritis) in a young female: report of a case].

A young female with aortitis syndrome (Takayasu's arteritis) and angina pectoris due to severe narrowing of the right and left coronary arterial ostia was presented. The thoracic and abdominal aorta and the distal coronary arteries were not involved. The exercise electrocardiogram and thallium-201 scanning were indicative of myocardial ischemia. Two-dimensional echocardiography did not disclose the stenosis of the ostia of the right and left coronary arteries. The final diagnosis was made by arteriography and coronary angiography. At the time of coronary arterial bypass graft operation, the ascending aorta in the vicinity of the coronary ostia was confirmed to be markedly thickened. Severe stenosis of the coronary ostia appeared to be due to proliferation of the aortic intima. Microscopic examination of the ascending thoracic aorta demonstrated lymphatic cell infiltrate and collagen fiber destruction in the adventitia and media. Angina pectoris may be the first symptom of the disease, when the coronary ostia are involved and the thoracic and abdominal aorta are not affected by arteritis. Both exercise electrocardiography and thallium-201 scanning prior to coronary angiography are recommended in evaluating this condition.

Adolescent↗