{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,18]],"date-time":"2025-10-18T20:38:22Z","timestamp":1760819902341},"reference-count":27,"publisher":"Proceedings of the National Academy of Sciences","issue":"46","content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[2006,11,14]]},"abstract":"<jats:p>\n            Sequence analysis of the diiron cluster-containing soluble desaturases suggests they are unrelated to other diiron enzymes; however, structural alignment of the core four-helix bundle of desaturases to other diiron enzymes reveals a conserved iron binding motif with similar spacing in all enzymes of this structural class, implying a common evolutionary ancestry. Detailed structural comparison of the castor desaturase with that of a peroxidase, rubrerythrin, shows remarkable conservation of both identity and geometry of residues surrounding the diiron center, with the exception of residue 199. Position 199 is occupied by a threonine in the castor desaturase, but the equivalent position in rubrerythrin contains a glutamic acid. We previously hypothesized that a carboxylate in this location facilitates oxidase chemistry in rubrerythrin by the close apposition of a residue capable of facilitating proton transfer to the activated oxygen (in a hydrophobic cavity adjacent to the diiron center based on the crystal structure of the oxygen-binding mimic azide). Here we report that desaturase mutant T199D binds substrate but its desaturase activity decreases by \u22482 \u00d7 10\n            <jats:sup>3<\/jats:sup>\n            -fold. However, it shows a &gt;31-fold increase in peroxide-dependent oxidase activity with respect to WT desaturase, as monitored by single-turnover stopped-flow spectrometry. A 2.65-\u00c5 crystal structure of T199D reveals active-site geometry remarkably similar to that of rubrerythrin, consistent with its enhanced function as an oxidase enzyme. That a single amino acid substitution can switch reactivity from desaturation to oxidation provides experimental support for the hypothesis that the desaturase evolved from an ancestral oxidase enzyme.\n          <\/jats:p>","DOI":"10.1073\/pnas.0607165103","type":"journal-article","created":{"date-parts":[[2006,11,7]],"date-time":"2006-11-07T01:54:23Z","timestamp":1162864463000},"page":"17220-17224","update-policy":"http:\/\/dx.doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":27,"title":["A single mutation in the castor \u0394\n            <sup>9<\/sup>\n            -18:0-desaturase changes reaction partitioning from desaturation to oxidase chemistry"],"prefix":"10.1073","volume":"103","author":[{"given":"Jodie E.","family":"Guy","sequence":"first","affiliation":[{"name":"*Department of Medical Biochemistry and Biophysics, Division of Molecular Structural Biology, Karolinska Institutet, Tomtebodav\u00e4gen 6, S-171 77 Stockholm, Sweden;"}]},{"given":"Isabel A.","family":"Abreu","sequence":"additional","affiliation":[{"name":"Department of Biology, Brookhaven National Laboratory, Upton, NY 11973; and"}]},{"given":"Martin","family":"Moche","sequence":"additional","affiliation":[{"name":"Department of Medical Biochemistry and Biophysics and Structural Genomics Consortium, Karolinska Institutet, S-171 77 Stockholm, Sweden"}]},{"given":"Ylva","family":"Lindqvist","sequence":"additional","affiliation":[{"name":"*Department of Medical Biochemistry and Biophysics, Division of Molecular Structural Biology, Karolinska Institutet, Tomtebodav\u00e4gen 6, S-171 77 Stockholm, Sweden;"}]},{"given":"Edward","family":"Whittle","sequence":"additional","affiliation":[{"name":"Department of Biology, Brookhaven National Laboratory, Upton, NY 11973; and"}]},{"given":"John","family":"Shanklin","sequence":"additional","affiliation":[{"name":"Department of Biology, Brookhaven National Laboratory, Upton, NY 11973; and"}]}],"member":"341","published-online":{"date-parts":[[2006,11,14]]},"reference":[{"key":"e_1_3_3_1_2","doi-asserted-by":"publisher","DOI":"10.1021\/cr9500489"},{"key":"e_1_3_3_2_2","doi-asserted-by":"publisher","DOI":"10.1002\/1521-3773(20020402)41:7<1114::AID-ANIE1114>3.0.CO;2-6"},{"key":"e_1_3_3_3_2","doi-asserted-by":"publisher","DOI":"10.1146\/annurev.arplant.49.1.611"},{"key":"e_1_3_3_4_2","doi-asserted-by":"publisher","DOI":"10.1002\/1439-7633(20010803)2:7\/8<583::AID-CBIC583>3.0.CO;2-5"},{"key":"e_1_3_3_5_2","doi-asserted-by":"publisher","DOI":"10.1021\/bi990841m"},{"key":"e_1_3_3_6_2","doi-asserted-by":"publisher","DOI":"10.1021\/bi981839i"},{"key":"e_1_3_3_7_2","doi-asserted-by":"publisher","DOI":"10.1074\/jbc.M301662200"},{"key":"e_1_3_3_8_2","doi-asserted-by":"publisher","DOI":"10.1021\/ja026587u"},{"key":"e_1_3_3_9_2","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.90.6.2486"},{"key":"e_1_3_3_10_2","doi-asserted-by":"publisher","DOI":"10.1021\/bi020340s"},{"key":"e_1_3_3_11_2","doi-asserted-by":"publisher","DOI":"10.1021\/bi991318a"},{"key":"e_1_3_3_12_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.jinorgbio.2005.12.017"},{"key":"e_1_3_3_13_2","doi-asserted-by":"publisher","DOI":"10.1021\/bi034220b"},{"key":"e_1_3_3_14_2","doi-asserted-by":"publisher","DOI":"10.1038\/80961"},{"key":"e_1_3_3_15_2","doi-asserted-by":"publisher","DOI":"10.1021\/ja044489y"},{"key":"e_1_3_3_16_2","doi-asserted-by":"publisher","DOI":"10.1074\/jbc.M102129200"},{"key":"e_1_3_3_17_2","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.210276297"},{"key":"e_1_3_3_18_2","doi-asserted-by":"publisher","DOI":"10.1023\/A:1005821007291"},{"key":"e_1_3_3_19_2","doi-asserted-by":"publisher","DOI":"10.1002\/j.1460-2075.1996.tb00783.x"},{"key":"e_1_3_3_20_2","doi-asserted-by":"publisher","DOI":"10.1107\/S090744499900846X"},{"key":"e_1_3_3_21_2","volume-title":"Data Collection and Processing","author":"Evans PR","year":"1993","unstructured":"PR Evans Data Collection and Processing (Daresbury Laboratory, Warrington, UK, 1993)."},{"key":"e_1_3_3_22_2","doi-asserted-by":"publisher","DOI":"10.1107\/S0907444994003112"},{"key":"e_1_3_3_23_2","doi-asserted-by":"publisher","DOI":"10.1107\/S0021889897006766"},{"key":"e_1_3_3_24_2","doi-asserted-by":"publisher","DOI":"10.1107\/S0907444998003254"},{"key":"e_1_3_3_25_2","doi-asserted-by":"publisher","DOI":"10.1107\/S0907444904019158"},{"key":"e_1_3_3_26_2","doi-asserted-by":"publisher","DOI":"10.1107\/S0021889892009944"},{"key":"e_1_3_3_27_2","volume-title":"The PyMOL Molecular Graphics System","author":"DeLano WL","year":"2002","unstructured":"WL DeLano The PyMOL Molecular Graphics System (DeLano Scientific, San Carlos, CA, 2002)."}],"container-title":["Proceedings of the National Academy of Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pnas.org\/doi\/pdf\/10.1073\/pnas.0607165103","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,4,12]],"date-time":"2022-04-12T19:41:32Z","timestamp":1649792492000},"score":1,"resource":{"primary":{"URL":"https:\/\/pnas.org\/doi\/full\/10.1073\/pnas.0607165103"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2006,11,14]]},"references-count":27,"journal-issue":{"issue":"46","published-print":{"date-parts":[[2006,11,14]]}},"alternative-id":["10.1073\/pnas.0607165103"],"URL":"https:\/\/doi.org\/10.1073\/pnas.0607165103","relation":{},"ISSN":["0027-8424","1091-6490"],"issn-type":[{"value":"0027-8424","type":"print"},{"value":"1091-6490","type":"electronic"}],"subject":[],"published":{"date-parts":[[2006,11,14]]},"assertion":[{"value":"2006-08-17","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2006-11-14","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}