title: Examination of the Tn5 transposase overproduction phenotype in Escherichia coli and localization of a suppressor of transposase overproduction killing that is an allele of rpoH.
abstract: Tn5 transposase (Tnp) overproduction is lethal to Escherichia coli. Tnp overproduction causes cell filamentation, abnormal chromosome segregation, and an increase in anucleated cell formation. There are two simple explanations for the observed phenotype: induction of the SOS response or of the heat shock response. The data presented here show that overproduction of Tnp neither induces an SOS response nor a strong heat shock response. However, our experiments do indicate that induction of some sigma32-programmed function(s) (either due to an rpoH mutation, a deletion of dnaK, or overproduction of sigma32) suppresses Tnp overproduction killing. This effect is not due to overproduction of DnaK, DnaJ, or GroELS. In addition, Tnp but not deltall Tnp (whose overproduction does not kill the host cells) associates with the inner cell membrane, suggesting a possible correlation between cell killing and Tnp membrane association. These observations will be discussed in the context of a model proposing that Tnp overproduction titrates an essential host factor(s) involved in an early cell division step and/or chromosome segregation.
authors.affiliation: Department of Biochemistry, University of Wisconsin--Madison, 53706, USA.
authors.forename: H
authors.initials: H
authors.lastname: Yigit
authors.forename: W S
authors.initials: WS
authors.lastname: Reznikoff
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology; D002462:Cell Membrane / Q000737:chemistry; D002467:Cell Nucleus / Q000378:metabolism; D018835:Chaperonin 10 / Q000096:biosynthesis; D018834:Chaperonin 60 / Q000096:biosynthesis; D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial / Q000502:physiology; D004254:DNA Nucleotidyltransferases / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D016153:Genes, Suppressor; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000502:physiology; D010641:Phenotype; D013014:SOS Response, Genetics; D012808:Sigma Factor / Q000235:genetics* / Q000502:physiology; D013489:Suppression, Genetic; D014157:Transcription Factors; D019895:Transposases
chemical_list: D001426:Bacterial Proteins; D018835:Chaperonin 10; D018834:Chaperonin 60; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D012808:Sigma Factor; D014157:Transcription Factors; C069774:heat-shock sigma factor 32; D004254:DNA Nucleotidyltransferases; D019895:Transposases; C063842:dnaK protein, E coli