乳糖操纵子模型的建立与教学中若干问题的解析
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摘要
基因结构和表达调控机制是现代生命科学的研究热点和焦点。乳糖操纵子是大肠杆菌(Escherichiacoli)分解代谢乳糖的一簇基因,其基因组成与表达调控方式是最早被阐明的基因结构与调控机制,因而成为微生物学、遗传学和分子生物学等多门专业课程讲解基因调控机制的经典教学案例和要求重点掌握的内容,备受师生们的重视。该知识点虽然结论简单,记忆容易,但由于触及生命结构与功能的核心机制,内涵丰富,逻辑深奥,理解困难。教师要充分发挥该教学案例的效果并非易事,需要深入了解乳糖操纵子的基因结构和工作原理,特别是科学家揭秘这些奥秘的科学背景和思维过程。本文通过回溯大肠杆菌乳糖操纵子发现和表达模式解析的历程,追随J. Monod和F. Jacob等前辈名家的脚印,聆听他们对实验结果的分析,学习他们的科研思想和创新思维,结合乳糖操纵子的DNA序列,深入分析和理解乳糖操纵子表达的若干奇特现象的原因,共同探讨如何充分发挥遗传学和分子生物学经典案例的教学价值。
Gene structure and expression regulation mechanism are the research hotspots and focus of modern life sciences. The lac operon is a cluster of genes through which Escherichia coli catabolizes lactose. It was first proposed by F. Jacob and J. Monod, who were also awarded the Nobel Prize in Physiology or Medicine in 1965 for their contributions. Thereafter, the lac operon has become the classic teaching case of the gene regulation mechanism in microbiology, genetics and molecular biology, and been highly valued by teachers and students alike. Although the conclusion is easy to follow and memorize, its rich connotation and esoteric reasoning has rendered it difficult to understand, neither is it easy for teachers to fully exploit the advantages of this teaching case. Therefore it is necessary to have an in-depth understanding of the genetic structure and working principle of the lac operon, especially the scientific background and thinking process through which scientists revealed these mysteries. In this paper, the historical discovery and analysis process of the E. coli lac operon was reviewed by following their footprints, listening to their analysis of experimental results. Based on the DNA sequences, the reasons for several unusual phenomena of lac operon expression were also discussed to exemplify the teaching value of the classic cases in genetics and molecular biology.
Gene structure and expression regulation mechanism are the research hotspots and focus of modern life sciences. The lac operon is a cluster of genes through which Escherichia coli catabolizes lactose. It was first proposed by F. Jacob and J. Monod, who were also awarded the Nobel Prize in Physiology or Medicine in 1965 for their contributions. Thereafter, the lac operon has become the classic teaching case of the gene regulation mechanism in microbiology, genetics and molecular biology, and been highly valued by teachers and students alike. Although the conclusion is easy to follow and memorize, its rich connotation and esoteric reasoning has rendered it difficult to understand, neither is it easy for teachers to fully exploit the advantages of this teaching case. Therefore it is necessary to have an in-depth understanding of the genetic structure and working principle of the lac operon, especially the scientific background and thinking process through which scientists revealed these mysteries. In this paper, the historical discovery and analysis process of the E. coli lac operon was reviewed by following their footprints, listening to their analysis of experimental results. Based on the DNA sequences, the reasons for several unusual phenomena of lac operon expression were also discussed to exemplify the teaching value of the classic cases in genetics and molecular biology.
引文
[1]Xing WJ,Morigen.Cultivating the scientific research ability of undergraduate students in teaching of genetics.Hereditas(Beijing),2016,38(11):1030-1038.邢万金,莫日根.在遗传学课堂教学中培养本科生科研素质.遗传,2016,38(11):1030-1038.
[2]Xing WJ,Morigen.Su HM.An exploration for research-oriented teaching model in biology teaching.Hereditas(Beijing),2014,36(7):732-738.邢万金,莫日根,苏慧敏.生物学教学中研究型教学方法与内容的探索.遗传,2014,36(7):732-738.
[3]Morigen,Xing WJ,Fan LF,Hada,Hasi A.Teaching practice of molecular biology in a scientific story-directed.J Biol,2016,33(5):112-116.莫日根,邢万金,范丽菲,哈达,哈斯阿古拉.科学史引导的分子生物学教学架构和实践.生物学杂志,2016,33(5):112-116.
[4]Wortmann J.Untersuchungenüber das diastatische ferment der bacterien.Hoppe-Seyler's Z.Physiol.Chem,1882,6(4-5):287-329.
[5]Duclaux E.Traitéde Microbiologie:Diastases,Toxines et venins,Vol.II.Masson et Cie,1899.
[6]Karstr?m H.über die enzymbildung in bakterien undüber einige physiologische Eigenschaften der untersuchten Bakterien.Ann Acad Sci Fen A,1930,33:2.
[7]Karstr?m H.Enzymatische adaptation bei mikroorganismen.Ergebnisse der Enzymforschung,1938,7:350-376.
[8]Yudkin J.Enzyme variation in micro-organisms.Biol Rev,1938,13(1):93-106.
[9]Monod J.Sur un phénomène nouveau de croissance complexe dans les cultures bactériennes.CR Acad Sci(Paris),1941,212:934-936.
[10]Monod J.Recherches sur la croissance des cultures bacteriennes.Paris:Hermann&Cie,1942.
[11]Diénert MF.Sur la fermentation du galactose et sur l'accoutumance des levuresàce sucre.E.Charaire,1900.
[12]Freeland JH.The eighth day of creation:the makers of the revolution in biology 1996.New-York:Cold Spring Harbor Laboratory Press.
[13]Spiegelman S.The physiology and genetic significance of enzymatic adaptation.Annals of the Missouri Botanical Garden,1945,32(2):139-163.
[14]Monod J.The phenomenon of enzymatic adaptation-and its bearings on problems of genetics and cellular differentiation.Growth,1947,11(4):223-289.
[15]Seidman M,Link K.New Compounds.substituted salicylaldehydes and derivatives.J Am Chem Soc,1950,72(9):4324-4324.
[16]Lederberg J.The beta-d-galactosidase of Escherichia coli,strain K-12.J Bacteriol,1950,60(4):381-392.
[17]Monod J,Cohen-Bazire G,Cohn M.Sur la biosynthese de laβ-galactosidase(lactase)chez Escherichia coli.La specificite de l'induction.Biochim Biophys Acta,1951,7:585-599.
[18]Herzenberg LA.Studies on the induction of beta-galactosidase in a cryptic strain of Escherichia coli.Biochim Biophys Acta,1959,31(2):525-538.
[19]Hickman M,Cairns J.The centenary of the one-gene one-enzyme hypothesis.Genetics,2003,163(3):839-841.
[20]Horowitz NH.One-gene-one-enzyme:remembering biochemical genetics.Protein Sci,1995,4(5):1017-1019.
[21]Monod J,Audureau A.Mutation and enzymatic adaptation in bact.coli-mutabile.Ann Inst Pasteur,1946,72(11/12):868-878.
[22]Lederberg J,Tatum EL.Gene recombination in Escherichia coli.Nature,1946,158(4016):558.
[23]Jacob F,Wollman E.Induction spontanée du developpement du bacteriophage lambda au cours de la recombinaison génétique chez Escherichia coli.C R Hebd Seances Acad Sci,1954,239(3):317-319.
[24]Wollman EL,Jacob F.Mechanism of the transfer of genetic material during recombination in Escherichia coli K12.C R Hebd Seances Acad Sci,1955,240(25):2449-2451.
[25]Cohen GN,Rickenberg HV.La galactosidepermease d'Escherichia coli.Ann Inst Pasteur,1956,91:693-720.
[26]Zabin I,Kepes A,Monod J.On the enzymic acetylation of isopropyl-β-d-thiogalactoside and its association with galactoside-permease.Biochem Biophys Res Commun,1959,1(6):289-292.
[27]Andrews KJ,Lin EC.Thiogalactoside transacetylase of the lactose operon as an enzyme for detoxification.JBacteriol,1976,128(1):510-513.
[28]Jacob F,Perrin D,Sánchez C,Monod J.L'opérongroupe de gènesàexpression coordonnée par un opérateur.C RHebd Seances Acad Sci,1960,250(9):1727-1729.
[29]Jacob F,Monod J.Genetic regulatory mechanisms in the synthesis of proteins.J Mol Biol,1961,3:318-356.
[30]Adelberg E,Burns SN.Genetic variation in the sex factor of Escherichia coli.J Bacteriol,Genetics,1960,79(3):321-330.
[31]Jacob F,Adelberg E.Transference of genetic properties by incorporation with the sexual factor of Escherichia coli.CR Hebd Seances Acad Sci,1959,249(1):189-191.
[32]Jacob F,Schaeffer P,Wollman EL.Episomic elements in bacteria.Symp Soc Gen Microbiol,1960,10:67-91.
[33]Pardee AB,Jacob F,Monod J.The genetic control and cytoplasmic expression of“Inducibility”in the synthesis ofβ-galactosidase by E.coli.J Mol Biol,1959,1(2):165-178.
[34]Jacob F,Monod J.Genetic regulatory mechanisms in the synthesis of proteins.J Mol Biol,1961,3(3):318-356.
[35]Crick FH.On protein synthesis.Symp Soc Exp Biol,1958,12:138-163.
[36]Monod J,Jacob F.Teleonomic mechanisms in cellular metabolism,growth,and differentiation.Cold Spring Harb Symp Quant Biol,1961.26:389-401.
[37]Horiuchi T,Novick A.A thermolabile repression system.Cold Spring Harb Symp Quant Biol,1961,26:247-248.
[38]Jacob F,Sussman R,Monod J.On the nature of the repressor ensuring the immunity of lysogenic bacteria.C RHebd Seances Acad Sci,1962,254:4214-4216.
[39]Gilbert W,Müller-Hill B.Isolation of the lac repressor.Proc Natl Acad Sci USA,1966,56(6):1891-1898.
[40]Changeux JP.The feedback control mechanisms of biosynthetic L-threonine deaminase by L-isoleucine.Cold Spring Harb Symp Quant Biol,1961,26:313-318.
[41]Monod J,Changeux JP,Jacob F.Allosteric proteins and cellular control systems.J Mol Biol,1963,6:306-329.
[42]Burstein C,Cohn M,Kepes A,Monod J.R?le du lactose et de ses produits métaboliques dans l'induction de l'opéron lactose chez Escherichia coli.Biochimica Et Biophysica Acta(Bba)-Nucleic Acids and Protein Synthesis,1965,95(4):634-639.
[43]Mueller-Hill B,Rickenberg HV,Wallenfels K.Specificity of the induction of the enzymes of the lac operon in Escherichia coli.J Mol Biol,1964,10:303-318.
[44]Jobe A,Bourgeois S.Lac Repressor-operator interaction.VI.The natural inducer of the lac operon.J Mol Biol,1972,69(3):397-408.
[45]Wallenfels K,Malhotra OP.Galactosidases.Adv Carbohydr Chem,1961,16:239-298.
[46]Huber RE,Kurz G,Wallenfels K.A quantitation of the factors which affect the hydrolase and transgalactosylase activities of beta-galactosidase(E.coli)on lactose.Biochemistry,1976,15(9):1994-2001.
[47]Xiong XF,de la Cruz N,Reznikoff WS.Downstream deletion analysis of the lac promoter.J Bacteriol,1991,173(15):4570-4577.
[48]Krebber A,Burmester J,Plückthun A.Inclusion of an upstream transcriptional terminator in phage display vectors abolishes background expression of toxic fusions with coat protein g3p.Gene,1996,178(1-2):71-74.
[49]Malan TP,McClure WR.Dual promoter control of the Escherichia coli lactose operon.Cell,1984,39(1):173-180.
[50]Donnelly CE,Reznikoff WS.Mutations in the lac P2promoter.J Bacteriol,1987,169(5):1812-1817.
[51]Fried M,Crothers DM.Equilibria and kinetics of lac repressor-operator interactions by polyacrylamide gel electrophoresis.Nucleic Acids Res,1981,9(23):6505-6525.
[52]Horowitz H,Platt T.A termination site for LacItranscription is between the CAP site and the lac promoter.J Biol Chem,1982,257(19):11740-11746.
[53]Gilbert W,Maxam A.The nucleotide sequence of the lac operator.Proc Natl Acad Sci USA,1973,70(12):3581-3584.
[54]Reznikoff WS,Winter RB,Hurley CK.The location of the repressor binding sites in the lac operon.Proc Natl Acad Sci USA,1974,71(6):2314-2318.
[55]Oehler S,Eismann ER,Kr?mer H,Müller-Hill B.The three operators of the lac operon cooperate in repression.Embo J,1990,9(4):973-979.
[56]Kania J,Müller-Hill B.Construction,isolation and implications of repressor-galactosidase-beta-galactosidase hybrid molecules.Eur J Biochem,1977,79(2):381-386.
[57]Kr?mer H,Niem?ller M,Amouyal M,Revet B,von Wilcken-Bergmann B,Müller-Hill B.Lac repressor forms loops with linear DNA carrying two suitably spaced lac operators.Embo J,1987,6(5):1481-1491.
[58]Becker NA,Peters JP,Maher LJ 3rd,Lionberger TA.Mechanism of promoter repression by Lac repressor-DNAloops.Nucleic Acids Res,2013,41(1):156-166.
[59]Kepes A.Sequential transcription and translation in the lactose operon of Escherichia coli.Biochim Biophys Acta,1967.138(1):107-123.
[60]Hediger MA,Johnson DF,Nierlich DP,Zabin I.DNAsequence of the lactose operon:the lacA gene and the transcriptional termination region.Proc Natl Acad Sci USA,1985,82(19):6414-6418.
[61]Zabin I,Fowler AV.Chapter III:β-galactosidase and thiogalactoside transacetylase.CSH Monograph Archive1970,1:27-47.
[62]Kennell D,Riezman H.Transcription and translation initiation frequencies of the Escherichia coli lac operon.JMol Biol,1977,114(1):1-21.
[63]de Crombrugghe B,Adhya S,Gottesman M,Pastan I.Effect of Rho on transcription of bacterial operons.Nat New Biol,1973,241(113):260-264.
[64]Lim LW,Kennel D.Evidence against transcription termination within the E.coli lac operon.Mol Gen Genet,1974,133(4):367-371.
[65]Murakawa GJ,Kwan C,Yamashita J,Nierlich DP.Transcription and decay of the lac messenger:role of an intergenic terminator.J Bacteriol,1991,173(1):28-36.
[66]Morse DE,Mosteller R,Baker RF,Yanofsky C.Direction of in vivo degradation of tryptophan messenger RNA-a correction.Nature,1969,223(5201):40-43.
[67]Morikawa N,Imamoto F.Degradation of tryptophan messenger.On the degradation of messenger RNA for the tryptophan operon in Escherichia coli.Nature,1969,223(5201):37-40.
[68]Morse DE,Mosteller RD,Yanofsky C.Dynamics of synthesis,translation,and degradation of trp operon messenger RNA in E.coli.Cold Spring Harb Symp Quant Biol,1969,34:725-740.
[69]Blundell M,Craig E,Kennell D.Decay rates of different mRNA in E.coli and models of decay.Nat New Biol,1972,238(80):46-49.
[70]Blundell M,Kennell D.Evidence for endonucleolytic attack in decay of lac messenger RNA in Escherichia coli.J Mol Biol,1974,83(2):143-161.
[71]Lim LW,Kennell D.Models for decay of Escherichia coli lac messenger RNA and evidence for inactivating cleavages between its messages.J Mol Biol,1979,135(2):369-390.
[2]Xing WJ,Morigen.Su HM.An exploration for research-oriented teaching model in biology teaching.Hereditas(Beijing),2014,36(7):732-738.邢万金,莫日根,苏慧敏.生物学教学中研究型教学方法与内容的探索.遗传,2014,36(7):732-738.
[3]Morigen,Xing WJ,Fan LF,Hada,Hasi A.Teaching practice of molecular biology in a scientific story-directed.J Biol,2016,33(5):112-116.莫日根,邢万金,范丽菲,哈达,哈斯阿古拉.科学史引导的分子生物学教学架构和实践.生物学杂志,2016,33(5):112-116.
[4]Wortmann J.Untersuchungenüber das diastatische ferment der bacterien.Hoppe-Seyler's Z.Physiol.Chem,1882,6(4-5):287-329.
[5]Duclaux E.Traitéde Microbiologie:Diastases,Toxines et venins,Vol.II.Masson et Cie,1899.
[6]Karstr?m H.über die enzymbildung in bakterien undüber einige physiologische Eigenschaften der untersuchten Bakterien.Ann Acad Sci Fen A,1930,33:2.
[7]Karstr?m H.Enzymatische adaptation bei mikroorganismen.Ergebnisse der Enzymforschung,1938,7:350-376.
[8]Yudkin J.Enzyme variation in micro-organisms.Biol Rev,1938,13(1):93-106.
[9]Monod J.Sur un phénomène nouveau de croissance complexe dans les cultures bactériennes.CR Acad Sci(Paris),1941,212:934-936.
[10]Monod J.Recherches sur la croissance des cultures bacteriennes.Paris:Hermann&Cie,1942.
[11]Diénert MF.Sur la fermentation du galactose et sur l'accoutumance des levuresàce sucre.E.Charaire,1900.
[12]Freeland JH.The eighth day of creation:the makers of the revolution in biology 1996.New-York:Cold Spring Harbor Laboratory Press.
[13]Spiegelman S.The physiology and genetic significance of enzymatic adaptation.Annals of the Missouri Botanical Garden,1945,32(2):139-163.
[14]Monod J.The phenomenon of enzymatic adaptation-and its bearings on problems of genetics and cellular differentiation.Growth,1947,11(4):223-289.
[15]Seidman M,Link K.New Compounds.substituted salicylaldehydes and derivatives.J Am Chem Soc,1950,72(9):4324-4324.
[16]Lederberg J.The beta-d-galactosidase of Escherichia coli,strain K-12.J Bacteriol,1950,60(4):381-392.
[17]Monod J,Cohen-Bazire G,Cohn M.Sur la biosynthese de laβ-galactosidase(lactase)chez Escherichia coli.La specificite de l'induction.Biochim Biophys Acta,1951,7:585-599.
[18]Herzenberg LA.Studies on the induction of beta-galactosidase in a cryptic strain of Escherichia coli.Biochim Biophys Acta,1959,31(2):525-538.
[19]Hickman M,Cairns J.The centenary of the one-gene one-enzyme hypothesis.Genetics,2003,163(3):839-841.
[20]Horowitz NH.One-gene-one-enzyme:remembering biochemical genetics.Protein Sci,1995,4(5):1017-1019.
[21]Monod J,Audureau A.Mutation and enzymatic adaptation in bact.coli-mutabile.Ann Inst Pasteur,1946,72(11/12):868-878.
[22]Lederberg J,Tatum EL.Gene recombination in Escherichia coli.Nature,1946,158(4016):558.
[23]Jacob F,Wollman E.Induction spontanée du developpement du bacteriophage lambda au cours de la recombinaison génétique chez Escherichia coli.C R Hebd Seances Acad Sci,1954,239(3):317-319.
[24]Wollman EL,Jacob F.Mechanism of the transfer of genetic material during recombination in Escherichia coli K12.C R Hebd Seances Acad Sci,1955,240(25):2449-2451.
[25]Cohen GN,Rickenberg HV.La galactosidepermease d'Escherichia coli.Ann Inst Pasteur,1956,91:693-720.
[26]Zabin I,Kepes A,Monod J.On the enzymic acetylation of isopropyl-β-d-thiogalactoside and its association with galactoside-permease.Biochem Biophys Res Commun,1959,1(6):289-292.
[27]Andrews KJ,Lin EC.Thiogalactoside transacetylase of the lactose operon as an enzyme for detoxification.JBacteriol,1976,128(1):510-513.
[28]Jacob F,Perrin D,Sánchez C,Monod J.L'opérongroupe de gènesàexpression coordonnée par un opérateur.C RHebd Seances Acad Sci,1960,250(9):1727-1729.
[29]Jacob F,Monod J.Genetic regulatory mechanisms in the synthesis of proteins.J Mol Biol,1961,3:318-356.
[30]Adelberg E,Burns SN.Genetic variation in the sex factor of Escherichia coli.J Bacteriol,Genetics,1960,79(3):321-330.
[31]Jacob F,Adelberg E.Transference of genetic properties by incorporation with the sexual factor of Escherichia coli.CR Hebd Seances Acad Sci,1959,249(1):189-191.
[32]Jacob F,Schaeffer P,Wollman EL.Episomic elements in bacteria.Symp Soc Gen Microbiol,1960,10:67-91.
[33]Pardee AB,Jacob F,Monod J.The genetic control and cytoplasmic expression of“Inducibility”in the synthesis ofβ-galactosidase by E.coli.J Mol Biol,1959,1(2):165-178.
[34]Jacob F,Monod J.Genetic regulatory mechanisms in the synthesis of proteins.J Mol Biol,1961,3(3):318-356.
[35]Crick FH.On protein synthesis.Symp Soc Exp Biol,1958,12:138-163.
[36]Monod J,Jacob F.Teleonomic mechanisms in cellular metabolism,growth,and differentiation.Cold Spring Harb Symp Quant Biol,1961.26:389-401.
[37]Horiuchi T,Novick A.A thermolabile repression system.Cold Spring Harb Symp Quant Biol,1961,26:247-248.
[38]Jacob F,Sussman R,Monod J.On the nature of the repressor ensuring the immunity of lysogenic bacteria.C RHebd Seances Acad Sci,1962,254:4214-4216.
[39]Gilbert W,Müller-Hill B.Isolation of the lac repressor.Proc Natl Acad Sci USA,1966,56(6):1891-1898.
[40]Changeux JP.The feedback control mechanisms of biosynthetic L-threonine deaminase by L-isoleucine.Cold Spring Harb Symp Quant Biol,1961,26:313-318.
[41]Monod J,Changeux JP,Jacob F.Allosteric proteins and cellular control systems.J Mol Biol,1963,6:306-329.
[42]Burstein C,Cohn M,Kepes A,Monod J.R?le du lactose et de ses produits métaboliques dans l'induction de l'opéron lactose chez Escherichia coli.Biochimica Et Biophysica Acta(Bba)-Nucleic Acids and Protein Synthesis,1965,95(4):634-639.
[43]Mueller-Hill B,Rickenberg HV,Wallenfels K.Specificity of the induction of the enzymes of the lac operon in Escherichia coli.J Mol Biol,1964,10:303-318.
[44]Jobe A,Bourgeois S.Lac Repressor-operator interaction.VI.The natural inducer of the lac operon.J Mol Biol,1972,69(3):397-408.
[45]Wallenfels K,Malhotra OP.Galactosidases.Adv Carbohydr Chem,1961,16:239-298.
[46]Huber RE,Kurz G,Wallenfels K.A quantitation of the factors which affect the hydrolase and transgalactosylase activities of beta-galactosidase(E.coli)on lactose.Biochemistry,1976,15(9):1994-2001.
[47]Xiong XF,de la Cruz N,Reznikoff WS.Downstream deletion analysis of the lac promoter.J Bacteriol,1991,173(15):4570-4577.
[48]Krebber A,Burmester J,Plückthun A.Inclusion of an upstream transcriptional terminator in phage display vectors abolishes background expression of toxic fusions with coat protein g3p.Gene,1996,178(1-2):71-74.
[49]Malan TP,McClure WR.Dual promoter control of the Escherichia coli lactose operon.Cell,1984,39(1):173-180.
[50]Donnelly CE,Reznikoff WS.Mutations in the lac P2promoter.J Bacteriol,1987,169(5):1812-1817.
[51]Fried M,Crothers DM.Equilibria and kinetics of lac repressor-operator interactions by polyacrylamide gel electrophoresis.Nucleic Acids Res,1981,9(23):6505-6525.
[52]Horowitz H,Platt T.A termination site for LacItranscription is between the CAP site and the lac promoter.J Biol Chem,1982,257(19):11740-11746.
[53]Gilbert W,Maxam A.The nucleotide sequence of the lac operator.Proc Natl Acad Sci USA,1973,70(12):3581-3584.
[54]Reznikoff WS,Winter RB,Hurley CK.The location of the repressor binding sites in the lac operon.Proc Natl Acad Sci USA,1974,71(6):2314-2318.
[55]Oehler S,Eismann ER,Kr?mer H,Müller-Hill B.The three operators of the lac operon cooperate in repression.Embo J,1990,9(4):973-979.
[56]Kania J,Müller-Hill B.Construction,isolation and implications of repressor-galactosidase-beta-galactosidase hybrid molecules.Eur J Biochem,1977,79(2):381-386.
[57]Kr?mer H,Niem?ller M,Amouyal M,Revet B,von Wilcken-Bergmann B,Müller-Hill B.Lac repressor forms loops with linear DNA carrying two suitably spaced lac operators.Embo J,1987,6(5):1481-1491.
[58]Becker NA,Peters JP,Maher LJ 3rd,Lionberger TA.Mechanism of promoter repression by Lac repressor-DNAloops.Nucleic Acids Res,2013,41(1):156-166.
[59]Kepes A.Sequential transcription and translation in the lactose operon of Escherichia coli.Biochim Biophys Acta,1967.138(1):107-123.
[60]Hediger MA,Johnson DF,Nierlich DP,Zabin I.DNAsequence of the lactose operon:the lacA gene and the transcriptional termination region.Proc Natl Acad Sci USA,1985,82(19):6414-6418.
[61]Zabin I,Fowler AV.Chapter III:β-galactosidase and thiogalactoside transacetylase.CSH Monograph Archive1970,1:27-47.
[62]Kennell D,Riezman H.Transcription and translation initiation frequencies of the Escherichia coli lac operon.JMol Biol,1977,114(1):1-21.
[63]de Crombrugghe B,Adhya S,Gottesman M,Pastan I.Effect of Rho on transcription of bacterial operons.Nat New Biol,1973,241(113):260-264.
[64]Lim LW,Kennel D.Evidence against transcription termination within the E.coli lac operon.Mol Gen Genet,1974,133(4):367-371.
[65]Murakawa GJ,Kwan C,Yamashita J,Nierlich DP.Transcription and decay of the lac messenger:role of an intergenic terminator.J Bacteriol,1991,173(1):28-36.
[66]Morse DE,Mosteller R,Baker RF,Yanofsky C.Direction of in vivo degradation of tryptophan messenger RNA-a correction.Nature,1969,223(5201):40-43.
[67]Morikawa N,Imamoto F.Degradation of tryptophan messenger.On the degradation of messenger RNA for the tryptophan operon in Escherichia coli.Nature,1969,223(5201):37-40.
[68]Morse DE,Mosteller RD,Yanofsky C.Dynamics of synthesis,translation,and degradation of trp operon messenger RNA in E.coli.Cold Spring Harb Symp Quant Biol,1969,34:725-740.
[69]Blundell M,Craig E,Kennell D.Decay rates of different mRNA in E.coli and models of decay.Nat New Biol,1972,238(80):46-49.
[70]Blundell M,Kennell D.Evidence for endonucleolytic attack in decay of lac messenger RNA in Escherichia coli.J Mol Biol,1974,83(2):143-161.
[71]Lim LW,Kennell D.Models for decay of Escherichia coli lac messenger RNA and evidence for inactivating cleavages between its messages.J Mol Biol,1979,135(2):369-390.