{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,30]],"date-time":"2026-05-30T05:30:43Z","timestamp":1780119043980,"version":"3.54.0"},"reference-count":39,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2022,11,28]],"date-time":"2022-11-28T00:00:00Z","timestamp":1669593600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["31801645"],"award-info":[{"award-number":["31801645"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["C2020204130"],"award-info":[{"award-number":["C2020204130"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Natural Science Foundation of Hebei Province","award":["31801645"],"award-info":[{"award-number":["31801645"]}]},{"name":"Natural Science Foundation of Hebei Province","award":["C2020204130"],"award-info":[{"award-number":["C2020204130"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Foods"],"abstract":"<jats:p>In this study, the identity of our recently produced natural TetR protein was identified by using the LC-ESI-MS\/MS technique, and its recognition mechanisms, including the binding pocket, contact amino acids, intermolecular forces, binding sites, binding energies, and affinities for 10 tetracycline drugs were studied. Then, it was evolved by site-mutagenesis of an amino acid to produce a mutant, and a fluorescence polarization assay was developed to detect the 10 drugs in milk. The sensitivities for the 10 drugs were improved with IC50 values decreasing from 30.8\u201380.1 ng\/mL to 15.5\u201355.2 ng\/mL, and the limits of detection were in the range of 0.4\u20131.5 ng\/mL. Furthermore, it was found that the binding affinity for a drug was the critical factor determining its sensitivity, and the binding energy showed little influence. This is the first study reporting the recognition mechanisms of a natural TetR protein for tetracyclines and the development of a fluorescence polarization assay for the detection of tetracyclines residues in food samples.<\/jats:p>","DOI":"10.3390\/foods11233850","type":"journal-article","created":{"date-parts":[[2022,11,29]],"date-time":"2022-11-29T01:42:02Z","timestamp":1669686122000},"page":"3850","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Identification and Evolution of a Natural Tetr Protein Based on Molecular Docking and Development of a Fluorescence Polari-Zation Assay for Multi-Detection of 10 Tetracyclines in Milk"],"prefix":"10.3390","volume":"11","author":[{"given":"Wanqiu","family":"Xia","sequence":"first","affiliation":[{"name":"College of Veterinary Medicine, Hebei Agricultural University, Baoding 071000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jing","family":"Liu","sequence":"additional","affiliation":[{"name":"College of Veterinary Medicine, Hebei Agricultural University, Baoding 071000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2112-0218","authenticated-orcid":false,"given":"Jianping","family":"Wang","sequence":"additional","affiliation":[{"name":"College of Veterinary Medicine, Hebei Agricultural University, Baoding 071000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,11,28]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"17","DOI":"10.1111\/j.1749-6632.2011.06354.x","article-title":"The history of the tetracyclines","volume":"1241","author":"Nelson","year":"2011","journal-title":"Ann. N. Y. Acad. Sci."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"C539","DOI":"10.1152\/ajpcell.00047.2010","article-title":"Tetracyclines: A pleitropic family of compounds with promising therapeutic properties. Review of the literature","volume":"299","author":"Griffin","year":"2010","journal-title":"Am. J. Physiol. Cell Ph."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1060","DOI":"10.1016\/S0006-291X(74)80296-2","article-title":"Detection of an inducible membrane protein associated with R-factor-mediated tetracycline resistance","volume":"56","author":"Levy","year":"1974","journal-title":"Biochem. Biophys. Res. Commun."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"6605","DOI":"10.1016\/S0021-9258(20)65186-9","article-title":"Purification of the TET repressor and TET operator from the transposons Tn10 and characterization of their interaction","volume":"252","author":"Hillen","year":"1982","journal-title":"J. Biol. Chem."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"418","DOI":"10.1126\/science.8153629","article-title":"Structure of the Tet repressor-tetracycline complex and regulation of antibiotic resistance","volume":"264","author":"Hinrichs","year":"1994","journal-title":"Science"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"260","DOI":"10.1006\/jmbi.1994.0138","article-title":"The complex formed between Tet repressor and tetracycline-Mg2+ reveals mechanism of antibiotic resistance","volume":"247","author":"Kisker","year":"1995","journal-title":"J. Mol. Biol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"439","DOI":"10.1006\/jmbi.1998.1775","article-title":"Conformational changes of the Tet repressor induced by tetracycline trapping","volume":"279","author":"Orth","year":"1998","journal-title":"J. Mol. Biol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"2042","DOI":"10.1002\/1521-3773(20000616)39:12<2042::AID-ANIE2042>3.0.CO;2-C","article-title":"The tetracycline repressor-A paradigm for a biological switch","volume":"39","author":"Saenger","year":"2000","journal-title":"Angew Chem. Int. Ed. Engl."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"215","DOI":"10.1038\/73324","article-title":"Structural basis of gene regulation by the tetracycline inducible Tet repressor-operator system","volume":"7","author":"Orth","year":"2000","journal-title":"Nat. Struct. Biol."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1719","DOI":"10.1128\/AAC.43.7.1719","article-title":"Reversal of tetracycline resistance mediated by different bacterial tetracycline resistance determinants by an inhibitor of the Tet(B) antiport protein","volume":"43","author":"Nelson","year":"1999","journal-title":"Antimicrob. Agents Chemother."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"844","DOI":"10.1016\/j.bbapap.2008.12.001","article-title":"Structures of AcrR and CmeR: Insight into the mechanisms of transcriptional repression and multi-drug recognition in the TetR family of regulators","volume":"1794","author":"Routh","year":"2009","journal-title":"BBA-Proteins Proteom."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"3289","DOI":"10.1016\/j.jmb.2013.06.013","article-title":"SCO4008, a putative TetR transcriptional repressor from Streptomyces coelicolor A3(2), regulates transcription of sco4007 by multidrug recognition","volume":"425","author":"Hayashi","year":"2013","journal-title":"J. Mol. Biol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"326","DOI":"10.1128\/MMBR.69.2.326-356.2005","article-title":"The TetR family of transcriptional repressors","volume":"69","author":"Ramos","year":"2005","journal-title":"Microbiol. Mol. Biol. Rev."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"847","DOI":"10.1016\/j.jmb.2010.05.062","article-title":"A comprehensive analysis of structural and sequence conservation in the TetR family transcriptional regulators","volume":"400","author":"Yu","year":"2010","journal-title":"J. Mol. Biol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"440","DOI":"10.1128\/MMBR.00018-13","article-title":"The TetR family of regulators","volume":"77","author":"Cuthbertson","year":"2013","journal-title":"Microbiol. Mol. Biol. Rev."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1699","DOI":"10.2174\/0929867013371743","article-title":"Efflux pump: Their role in antibacterial drug discover","volume":"14","author":"Lomovskaya","year":"2001","journal-title":"Curr. Med. Chem."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"4365","DOI":"10.1128\/JB.00716-13","article-title":"Characterization of SAV7471, a TetR-family transcriptional regulator involved in the regulation of coenzyme A metabolism in Streptomyces avermitilis","volume":"195","author":"Liu","year":"2013","journal-title":"J. Bacteriol."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"904","DOI":"10.1016\/j.jksus.2019.05.003","article-title":"Evaluation of the inhibitory effect of caffeicacid and gallic acid on tetR and tetM efflux pumps mediating tetracycline resistance in Streptococcus sp, using computational approach","volume":"32","author":"Sivaharini","year":"2020","journal-title":"J. King Saud. Univ. Sci."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"205","DOI":"10.1016\/j.cbi.2014.12.034","article-title":"Isolation and identification of a repressor TetR for 3,17b-HSD expressional regulation in Comamonas testosterone","volume":"234","author":"Pan","year":"2015","journal-title":"Chem.-Biol. Interact."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"71","DOI":"10.1186\/s13568-019-0801-x","article-title":"Isolation and identification of a TetR familyprotein that regulates the biodesulfurization operon","volume":"9","author":"Pooja","year":"2019","journal-title":"AMB Express."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"671","DOI":"10.1016\/j.ijbiomac.2019.09.009","article-title":"Characterization of DNA binding and ligand binding properties of theTetR family protein involved in regulation of dsz operon in Gordoniasp. IITR100","volume":"141","author":"Murarka","year":"2019","journal-title":"Int. J. Biol. Macromol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"263","DOI":"10.1016\/S0014-5793(00)01728-2","article-title":"A direct photo-activated affinity modification of tetracycline transcription repressor protein TetR(D) with tetracycline","volume":"477","author":"Beliakova","year":"2000","journal-title":"FEBS Lett."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"7990","DOI":"10.1021\/bi5012805","article-title":"Tetracycline repressor allostery does not depend on divalent metal recognition","volume":"53","author":"Werten","year":"2014","journal-title":"Biochemistry"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"2102","DOI":"10.1111\/febs.13723","article-title":"Modular organisation of inducer recognition and allostery in the tetracycline repressor","volume":"283","author":"Werten","year":"2016","journal-title":"FEBS J."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1037","DOI":"10.1021\/bi048548w","article-title":"Kinetic and thermodynamic studies of Tet repressor-tetracycline interaction","volume":"44","author":"Gorecki","year":"2005","journal-title":"Biochemistry"},{"key":"ref_26","first-page":"52","article-title":"Determination of a fraction of the transcription repressor protein TetR(D) active for binding of tetracycline by a competitive binding method","volume":"60","author":"Alpeeva","year":"2005","journal-title":"Mosc. Univ. Chem. Bull."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"140404","DOI":"10.1016\/j.bbapap.2020.140404","article-title":"Thermodynamics, cooperativity and stability of the tetracycline repressor(TetR) upon tetracycline binding","volume":"1868","author":"Palm","year":"2020","journal-title":"BBA-Proteins Proteom."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"260","DOI":"10.1016\/j.trac.2018.10.011","article-title":"Recent advances in sensors for tetracycline antibiotics and their applications","volume":"109","author":"Liu","year":"2018","journal-title":"TrAC-Trend Anal. Chem."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"104184","DOI":"10.1016\/j.microc.2019.104184","article-title":"Directional evolution of TetR protein and development of a fluoroimmunoassay for screening of tetracyclines in egg","volume":"150","author":"Wang","year":"2019","journal-title":"Microchem. J."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"40","DOI":"10.1016\/j.ab.2018.10.017","article-title":"A receptor-based chemiluminescence enzyme linked immunosorbent assay for determination of tetracyclines in milk","volume":"564\u2013565","author":"Wang","year":"2019","journal-title":"Anal. Biochem."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"9","DOI":"10.1002\/bit.20224","article-title":"Broad-spectrum protein biosensors for class-specific detection of antibiotics","volume":"89","author":"Weber","year":"2005","journal-title":"Biotechnol. Bioeng."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"668","DOI":"10.1016\/j.jbiotec.2006.11.011","article-title":"A novel generic dipstick-based technology for rapid and precise detection of tetracycline, streptogramin and macrolide antibiotics in food samples","volume":"128","author":"Link","year":"2007","journal-title":"J. Biotechnol."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"10036","DOI":"10.1021\/acs.analchem.6b02294","article-title":"Multianalyte antibiotic detection on an electrochemical microfluidic platform","volume":"88","author":"Kling","year":"2016","journal-title":"Anal. Chem."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"3467","DOI":"10.1007\/s00216-019-02368-y","article-title":"Flow-based regenerable chemiluminescence receptor assay for the detection of tetracyclines","volume":"412","author":"Meyer","year":"2020","journal-title":"Anal. Bioanal. Chem."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"293","DOI":"10.1016\/j.trac.2019.03.013","article-title":"Fluorescence polarization assays for chemical contaminants in food and environmental analyses","volume":"114","author":"Zhang","year":"2019","journal-title":"TrAC-Trend Anal. Chem."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"106779","DOI":"10.1016\/j.microc.2021.106779","article-title":"Synthesis of photoaffinity labeled activity-based protein profiling probe and production of natural TetR protein for immunoassay of tetracyclines in milk","volume":"170","author":"Xia","year":"2021","journal-title":"Microchem. J."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"3023","DOI":"10.1021\/acs.jafc.2c00337","article-title":"Production of a natural dihydropteroate synthase and development of a signal amplified pseudo immunoassay for determination of sulfonamides in pork","volume":"70","author":"He","year":"2022","journal-title":"J. Agric. Food Chem."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"13953","DOI":"10.1021\/acs.jafc.1c05674","article-title":"Development of a dihydropteroate synthase based fluorescence polarization assay for detection of sulfonamides and studying its recognition mechanism","volume":"69","author":"He","year":"2021","journal-title":"J. Agric. Food Chem."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"1211","DOI":"10.1007\/s12161-020-01744-0","article-title":"Determination of tetracyclines in chicken bydispersive solid phase microextraction based on metal-organic frameworks\/molecularly imprinted nano-polymer and ultra performance liquid chromatography","volume":"13","author":"Ma","year":"2020","journal-title":"Food Anal. 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