Abstract:
:Three of the four deoxynucleoside kinases required for growth of Lactobacillus acidophilus R-26 exist as heterodimeric pairs specific for deoxyadenosine (dAK) and deoxycytidine (dCK) or dAK and deoxyguanosine (dGK). However, only two tandem genes, dak/dgk, are found, and are expressed only as dAK/dGK in transformed Escherichia coli. Sequencing peptides spanning 63% of the native dCK subunit revealed a sequence identical to that deduced from dgk (beginning MTVIVL...), except that dCK lacks residues 2 and 3 (dCK is M..IVL; dGK is .TVIVL). Also, mass spectrometry indicates that native dCK and dGK subunits are identical in mass adjusted for the first three residues. Furthermore, the native enzymes have identical isoelectric pH values, indicating an equal number of charged residues. To enable E. coli to express peptide having the native dCK sequence, codons 2 and 3 were deleted from the dgk portion of the tandem genes, resulting in expression of protein having the specificities and regulatory properties of native dAK/dCK, including heterotropic stimulation of dAK activity by deoxycytidine or dCTP (not deoxyguanosine or dGTP) and end-product inhibition of the respective activities by dATP and dCTP. Subcloning normal and mutant dgk yielded homodimeric dGK and dCK, respectively. The dCK homodimer strongly resembles human dCK, with a low K(m) for deoxycytidine, the ability to phosphorylate deoxyadenosine and deoxyguanosine at much higher K(m) values, and end-product inhibition by dCTP. Thus two distinct and specific enzymes evidently are derived from a single Lactobacillus gene. The mechanism by which this occurs in vivo has yet to be elucidated.
journal_name
Proc Natl Acad Sci U S Aauthors
Ma N,Ikeda S,Guo S,Fieno A,Park I,Grimme S,Ikeda T,Ives DHdoi
10.1073/pnas.93.25.14385subject
Has Abstractpub_date
1996-12-10 00:00:00pages
14385-90issue
25eissn
0027-8424issn
1091-6490journal_volume
93pub_type
杂志文章abstract::The human T cell leukemia virus I basic leucine zipper protein (HTLV-1 HBZ) maintains chronic viral infection and promotes leukemogenesis through poorly understood mechanisms involving interactions with the KIX domain of the transcriptional coactivator CBP and its paralog p300. The KIX domain binds regulatory proteins...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
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更新日期:2018-10-02 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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doi:10.1073/pnas.74.4.1393
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更新日期:2004-05-11 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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abstract::The selective alteration of the cellular genome by laser microbeam irradiation has been extensively applied in cell biology. We report here the use of the third harmonic (355 nm) of an yttrium-aluminum garnet laser to facilitate the direct transfer of the neo gene into cultured human HT1080-6TG cells. The resultant tr...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:1999-12-21 00:00:00
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更新日期:2001-01-16 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:2001-03-27 00:00:00
abstract::The gamma-aminobutyrate-synthesizing enzyme glutamate decarboxylase (GAD; L-glutamate 1-carboxy-lyase, EC 4.1.1.15) is a major target of autoantibodies associated with both early and late stages of pancreatic beta-cell destruction and development of type 1 diabetes. We have used five monoclonal anti-islet-cell antibod...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:1993-04-01 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
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更新日期:2017-05-09 00:00:00