IDENTIFICATION OF THE ESCHERICHIA COLI LEXA PROTEIN AND REGULATION OF LEXA GENE EXPRESSION IN VIVO.

Persistent Link:
http://hdl.handle.net/10150/185537
Title:
IDENTIFICATION OF THE ESCHERICHIA COLI LEXA PROTEIN AND REGULATION OF LEXA GENE EXPRESSION IN VIVO.
Author:
HARPER, JOAN ELIZABETH.
Issue Date:
1983
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The product of the Escherichia coli lexA gene has been identified, and the regulation of lexA gene expression in vivo has been examined. A series of specialized transducing phages carring lexA⁺ and 3 different amber lexA alleles was constructed by in vivo recombination between λlexA3 and host lexA alleles. These phages were characterized extensively to confirm that they carried the appropriate lexA allele. The lexA gene product was identified by comparison of the polypeptides encoded by λlexA3 and the amber lexA phages. A 24,000 dalton polypeptide, synthesized after infection of both amber-suppressor and non-suppressor hosts by λlexA3 was not synthesized following amber lexA phage infection of non-suppressor hosts. Synthesis of this polypeptide following amber lexA phage infection was restored by the presence of an amber suppressor mutation in the host. On the basis of these data, the 24,000 dalton polypeptide was identified as the lexA gene product. Regulation of lexA gene expression in vivo was examined by hybridization experiments to measure lexA mRNA levels. The basla level of lexA mRNA in wild type E. coli was found to be .006% of total mRNA. Treatment of the bacteria with 100 erglmm² ultraviolet irradiation (UV) led to an eight-fold increase in lexA mRNA levels within 10 minutes, the lexA mRNA remained elevated until 70 minutes after irradiation, then slowly declined. By comparison, the level of recA mRNA increased from .05% to .51% of total mRNA within 10 minutes following UV irradiation, then declined. Both lexA and recA genes were induced by nalidixic acid treatment; the induction was not as rapid as UV induction and different relative induction kinetics of the two genes were seen. The levels of lexA and recA mRNAS were measured in several mutant strains following UV-irradiation.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Escherichia coli -- Genetics.; DNA repair.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Molecular and Medical Microbiology; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Mount, David

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleIDENTIFICATION OF THE ESCHERICHIA COLI LEXA PROTEIN AND REGULATION OF LEXA GENE EXPRESSION IN VIVO.en_US
dc.creatorHARPER, JOAN ELIZABETH.en_US
dc.contributor.authorHARPER, JOAN ELIZABETH.en_US
dc.date.issued1983en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe product of the Escherichia coli lexA gene has been identified, and the regulation of lexA gene expression in vivo has been examined. A series of specialized transducing phages carring lexA⁺ and 3 different amber lexA alleles was constructed by in vivo recombination between λlexA3 and host lexA alleles. These phages were characterized extensively to confirm that they carried the appropriate lexA allele. The lexA gene product was identified by comparison of the polypeptides encoded by λlexA3 and the amber lexA phages. A 24,000 dalton polypeptide, synthesized after infection of both amber-suppressor and non-suppressor hosts by λlexA3 was not synthesized following amber lexA phage infection of non-suppressor hosts. Synthesis of this polypeptide following amber lexA phage infection was restored by the presence of an amber suppressor mutation in the host. On the basis of these data, the 24,000 dalton polypeptide was identified as the lexA gene product. Regulation of lexA gene expression in vivo was examined by hybridization experiments to measure lexA mRNA levels. The basla level of lexA mRNA in wild type E. coli was found to be .006% of total mRNA. Treatment of the bacteria with 100 erglmm² ultraviolet irradiation (UV) led to an eight-fold increase in lexA mRNA levels within 10 minutes, the lexA mRNA remained elevated until 70 minutes after irradiation, then slowly declined. By comparison, the level of recA mRNA increased from .05% to .51% of total mRNA within 10 minutes following UV irradiation, then declined. Both lexA and recA genes were induced by nalidixic acid treatment; the induction was not as rapid as UV induction and different relative induction kinetics of the two genes were seen. The levels of lexA and recA mRNAS were measured in several mutant strains following UV-irradiation.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectEscherichia coli -- Genetics.en_US
dc.subjectDNA repair.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineMolecular and Medical Microbiologyen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorMount, Daviden_US
dc.contributor.committeememberRost, Ricken_US
dc.contributor.committeememberHewlett, Martyen_US
dc.contributor.committeememberMcReynold, Larryen_US
dc.contributor.committeememberMeinke, Billen_US
dc.identifier.proquest8311410en_US
dc.identifier.oclc688340264en_US
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