{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,20]],"date-time":"2026-05-20T07:22:14Z","timestamp":1779261734036,"version":"3.51.4"},"reference-count":43,"publisher":"American Association for the Advancement of Science (AAAS)","issue":"4980","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Science"],"published-print":{"date-parts":[[1990,10,26]]},"abstract":"<jats:p>\n            Expression of the L-arabinose BAD operon in\n            <jats:italic>Escherichia coli<\/jats:italic>\n            is regulated by AraC protein which acts both positively in the presence of arabinose to induce transcription and negatively in the absence of arabinose to repress transcription. The repression of the\n            <jats:italic>araBAD<\/jats:italic>\n            promoter is mediated by DNA looping between AraC protein bound at two sites near the promoter separated by 210 base pairs,\n            <jats:italic>araI<\/jats:italic>\n            and\n            <jats:italic>araO<\/jats:italic>\n            <jats:sub>2<\/jats:sub>\n            . In vivo and in vitro experiments presented here show that an AraC dimer, with binding to half of\n            <jats:italic>araI<\/jats:italic>\n            and to\n            <jats:italic>araO<\/jats:italic>\n            <jats:sub>2<\/jats:sub>\n            , maintains the repressed state of the operon. The addition of arabinose, which induces the operon, breaks the loop, and shifts the interactions from the distal\n            <jats:italic>araO<\/jats:italic>\n            <jats:sub>2<\/jats:sub>\n            site to the previously unoccupied half of the\n            <jats:italic>araI<\/jats:italic>\n            site. The conversion between the two states does not require additional binding of AraC protein and appears to be driven largely by properties of the protein rather than being specified by the slightly different DNA sequences of the binding sites. Slight reorientation of the subunits of AraC could specify looping or unlooping by the protein. Such a mechanism could account for regulation of DNA looping in other systems.\n          <\/jats:p>","DOI":"10.1126\/science.2237403","type":"journal-article","created":{"date-parts":[[2006,10,5]],"date-time":"2006-10-05T22:10:14Z","timestamp":1160086214000},"page":"528-532","source":"Crossref","is-referenced-by-count":195,"title":["DNA Looping and Unlooping by AraC Protein"],"prefix":"10.1126","volume":"250","author":[{"given":"Robert B.","family":"Lobell","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Robert F.","family":"Schleif","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"221","reference":[{"key":"e_1_2_1_1_1","doi-asserted-by":"crossref","first-page":"545","DOI":"10.1016\/0092-8674(89)90435-2","volume":"58","year":"1989","unstructured":"AMOUYAL, M, SINGLE AND DOUBLE LOOP FORMATION WHEN DEOR REPRESSOR BINDS TO ITS NATURAL OPERATOR SITES, CELL 58: 545 (1989).","journal-title":"CELL"},{"key":"e_1_2_1_2_1","doi-asserted-by":"crossref","first-page":"304","DOI":"10.1038\/290304a0","volume":"290","year":"1981","unstructured":"BENOIST, C, INVIVO SEQUENCE REQUIREMENTS OF THE SV40 EARLY PROMOTER REGION, NATURE 290: 304 (1981).","journal-title":"NATURE"},{"key":"e_1_2_1_3_1","doi-asserted-by":"crossref","first-page":"1377","DOI":"10.1002\/j.1460-2075.1986.tb04370.x","volume":"5","year":"1986","unstructured":"BESSE, M, SYNTHETIC LAC OPERATOR MEDIATES REPRESSION THROUGH LAC REPRESSOR WHEN INTRODUCED UPSTREAM AND DOWNSTREAM FROM LAC PROMOTER, EMBO JOURNAL 5: 1377 (1986).","journal-title":"EMBO JOURNAL"},{"key":"e_1_2_1_4_1","doi-asserted-by":"crossref","first-page":"101","DOI":"10.1016\/0022-2836(87)90513-4","volume":"196","year":"1987","unstructured":"BOROWIEC, J.A., DNA SUPERCOILING PROMOTES FORMATION OF A BENT REPRESSION LOOP IN LAC DNA, JOURNAL OF MOLECULAR BIOLOGY 196: 101 (1987).","journal-title":"JOURNAL OF MOLECULAR BIOLOGY"},{"key":"e_1_2_1_5_1","doi-asserted-by":"crossref","first-page":"607","DOI":"10.1016\/0022-2836(89)90598-6","volume":"209","year":"1989","unstructured":"BRUNELLE, A, DETERMINING RESIDUE-BASE INTERACTIONS BETWEEN ARAC-PROTEIN AND ARAI DNA, JOURNAL OF MOLECULAR BIOLOGY 209: 607 (1989).","journal-title":"JOURNAL OF MOLECULAR BIOLOGY"},{"key":"e_1_2_1_6_1","doi-asserted-by":"crossref","first-page":"551","DOI":"10.1016\/0092-8674(88)90468-0","volume":"52","year":"1988","unstructured":"CHATTORAJ, D.K., MINI-P1 PLASMID REPLICATION - THE AUTOREGULATION-SEQUESTRATION PARADOX, CELL 52: 551 (1988).","journal-title":"CELL"},{"key":"e_1_2_1_7_1","doi-asserted-by":"crossref","first-page":"856","DOI":"10.1038\/332856a0","volume":"332","year":"1988","unstructured":"COHEN, R.S., PERIODIC INTERACTIONS OF HEAT-SHOCK TRANSCRIPTIONAL ELEMENTS, NATURE 332: 856 (1988).","journal-title":"NATURE"},{"key":"e_1_2_1_8_1","doi-asserted-by":"crossref","first-page":"3333","DOI":"10.1002\/j.1460-2075.1985.tb04085.x","volume":"4","year":"1985","unstructured":"DANDANELL, G, EMBO JOURNAL 4: 3333 (1985).","journal-title":"EMBO JOURNAL"},{"key":"e_1_2_1_9_1","doi-asserted-by":"publisher","DOI":"10.1126\/science.2544029"},{"key":"e_1_2_1_10_1","first-page":"5017","volume":"81","year":"1984","unstructured":"DUNN, T.M., AN OPERATOR AT -280 BASE-PAIRS THAT IS REQUIRED FOR REPRESSION OF ARABAD OPERON PROMOTER - ADDITION OF DNA HELICAL TURNS BETWEEN THE OPERATOR AND PROMOTER CYCLICALLY HINDERS REPRESSION, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA-BIOLOGICAL SCIENCES 81: 5017 (1984).","journal-title":"PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA-BIOLOGICAL SCIENCES"},{"key":"e_1_2_1_11_1","doi-asserted-by":"crossref","first-page":"946","DOI":"10.1128\/jb.90.4.946-957.1965","volume":"90","year":"1965","unstructured":"ENGLESBERG, E, POSITIVE CONTROL OF ENZYME SYNTHESIS BY GENE C IN L-ARABINOSE SYSTEM, JOURNAL OF BACTERIOLOGY 90: 946 (1965).","journal-title":"JOURNAL OF BACTERIOLOGY"},{"key":"e_1_2_1_12_1","doi-asserted-by":"publisher","DOI":"10.1093\/nar\/9.23.6505"},{"key":"e_1_2_1_13_1","doi-asserted-by":"publisher","DOI":"10.1093\/nar\/9.13.3047"},{"key":"e_1_2_1_14_1","doi-asserted-by":"crossref","first-page":"750","DOI":"10.1038\/322750a0","volume":"322","year":"1986","unstructured":"GRIFFITH, J, DNA LOOPS INDUCED BY COOPERATIVE BINDING OF LAMBDA-REPRESSOR, NATURE 322: 750 (1986).","journal-title":"NATURE"},{"key":"e_1_2_1_15_1","doi-asserted-by":"crossref","first-page":"61","DOI":"10.1016\/0022-2836(84)90430-3","volume":"180","year":"1984","unstructured":"HAHN, S, UPSTREAM REPRESSION AND CRP STIMULATION OF THE ESCHERICHIA-COLI L-ARABINOSE OPERON, JOURNAL OF MOLECULAR BIOLOGY 180: 61 (1984).","journal-title":"JOURNAL OF MOLECULAR BIOLOGY"},{"key":"e_1_2_1_16_1","doi-asserted-by":"crossref","first-page":"355","DOI":"10.1016\/0022-2836(86)90160-9","volume":"188","year":"1986","unstructured":"HAHN, S, TRANSCRIPTION OF ESCHERICHIA-COLI ARA INVITRO - THE CYCLIC-AMP RECEPTOR PROTEIN REQUIREMENT FOR PBAD INDUCTION THAT DEPENDS ON THE PRESENCE AND ORIENTATION OF THE ARAO2 SITE, JOURNAL OF MOLECULAR BIOLOGY 188: 355 (1986).","journal-title":"JOURNAL OF MOLECULAR BIOLOGY"},{"key":"e_1_2_1_17_1","first-page":"1749","volume":"85","year":"1988","unstructured":"HAMILTON, E.P., 3 BINDING-SITES FOR ARAC PROTEIN ARE REQUIRED FOR AUTO-REGULATION OF ARAC IN ESCHERICHIA-COLI, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 85: 1749 (1988).","journal-title":"PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA"},{"key":"e_1_2_1_18_1","doi-asserted-by":"crossref","first-page":"611","DOI":"10.1016\/0022-2836(84)90241-9","volume":"178","year":"1984","unstructured":"HENDRICKSON, W, REGULATION OF THE ESCHERICHIA-COLI L-ARABINOSE OPERON STUDIED BY GEL-ELECTROPHORESIS DNA-BINDING ASSAY, JOURNAL OF MOLECULAR BIOLOGY 178: 611 (1984).","journal-title":"JOURNAL OF MOLECULAR BIOLOGY"},{"key":"e_1_2_1_19_1","first-page":"3129","volume":"82","year":"1985","unstructured":"HENDRICKSON, W, A DIMER OF ARAC PROTEIN CONTACTS 3 ADJACENT MAJOR GROOVE REGIONS OF THE ARAI DNA SITE, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 82: 3129 (1985).","journal-title":"PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA"},{"key":"e_1_2_1_20_1","doi-asserted-by":"crossref","first-page":"681","DOI":"10.1016\/0092-8674(86)90833-0","volume":"44","year":"1986","unstructured":"HOCHSCHILD, A, COOPERATIVE BINDING OF LAMBDA-REPRESSORS TO SITES SEPARATED BY INTEGRAL TURNS OF THE DNA HELIX, CELL 44: 681 (1986).","journal-title":"CELL"},{"key":"e_1_2_1_21_1","first-page":"5444","volume":"85","year":"1988","unstructured":"HUO, L, ALTERNATIVE DNA LOOPS REGULATE THE ARABINOSE OPERON IN ESCHERICHIA-COLI, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 85: 5444 (1988).","journal-title":"PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA"},{"key":"e_1_2_1_22_1","doi-asserted-by":"crossref","first-page":"783","DOI":"10.1016\/0092-8674(83)90064-8","volume":"32","year":"1983","unstructured":"Irani, M., Cell 32: 783 (1983).","journal-title":"Cell"},{"key":"e_1_2_1_23_1","doi-asserted-by":"crossref","first-page":"781","DOI":"10.1016\/S0092-8674(85)80059-3","volume":"41","year":"1985","unstructured":"JOHNSON, R.C., HIN-MEDIATED SITE-SPECIFIC RECOMBINATION REQUIRES 2 26-BP RECOMBINATION SITES AND A 60-BP RECOMBINATIONAL ENHANCER, CELL 41: 781 (1985).","journal-title":"CELL"},{"key":"e_1_2_1_24_1","doi-asserted-by":"crossref","first-page":"462","DOI":"10.1038\/329462a0","volume":"329","year":"1987","unstructured":"JOHNSON, R.C., SPATIAL RELATIONSHIP OF THE FIS BINDING-SITES FOR HIN RECOMBINATIONAL ENHANCER ACTIVITY, NATURE 329: 462 (1987).","journal-title":"NATURE"},{"key":"e_1_2_1_25_1","doi-asserted-by":"crossref","first-page":"1481","DOI":"10.1002\/j.1460-2075.1987.tb02390.x","volume":"6","year":"1987","unstructured":"KRAMER, H, LAC REPRESSOR FORMS LOOPS WITH LINEAR DNA CARRYING 2 SUITABLY SPACED LAC OPERATORS, EMBO JOURNAL 6: 1481 (1987).","journal-title":"EMBO JOURNAL"},{"key":"e_1_2_1_26_1","doi-asserted-by":"crossref","first-page":"547","DOI":"10.1002\/j.1460-2075.1988.tb02844.x","volume":"7","year":"1988","unstructured":"KRAMER, H, DNA SUPERCOILING CHANGES THE SPACING REQUIREMENT OF 2 LAC OPERATORS FOR DNA LOOP FORMATION WITH LAC REPRESSOR, EMBO JOURNAL 7: 547 (1988).","journal-title":"EMBO JOURNAL"},{"key":"e_1_2_1_27_1","first-page":"8814","volume":"84","year":"1987","unstructured":"LEE, N, ARABINOSE-INDUCED BINDING OF ARAC PROTEIN TO ARAL2 ACTIVATES THE ARABAD OPERON PROMOTER, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 84: 8814 (1987).","journal-title":"PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA"},{"key":"e_1_2_1_28_1","first-page":"752","volume":"78","year":"1981","unstructured":"LEE, N.L., MECHANISM OF ARAC AUTO-REGULATION AND THE DOMAINS OF 2 OVERLAPPING PROMOTERS, PC AND PBAD, IN THE L-ARABINOSE REGULATORY REGION OF ESCHERICHIA-COLI, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA-BIOLOGICAL SCIENCES 78: 752 (1981).","journal-title":"PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA-BIOLOGICAL SCIENCES"},{"key":"e_1_2_1_29_1","doi-asserted-by":"crossref","first-page":"811","DOI":"10.1128\/jb.169.2.811-822.1987","volume":"169","year":"1987","unstructured":"LICHENSTEIN, H.S., REPRESSION AND CATABOLITE GENE ACTIVATION IN THE ARABAD OPERON, JOURNAL OF BACTERIOLOGY 169: 811 (1987).","journal-title":"JOURNAL OF BACTERIOLOGY"},{"key":"e_1_2_1_30_1","unstructured":"LOBELL R THESIS BRANDEIS U (1990)."},{"key":"e_1_2_1_31_1","unstructured":"LOBELL R unpublished data."},{"key":"e_1_2_1_32_1","first-page":"3654","volume":"83","year":"1986","unstructured":"MARTIN, K, THE DNA LOOP MODEL FOR ARA REPRESSION - 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