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
H. Yigit et Ws. Reznikoff, 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, Journal of bacteriology, 179(5), 1997, pp. 1704-1713
Tn5 transposase (Tnp) overproduction is lethal to Escherichia coli, Tn
p overproduction causes cell filamentation, abnormal chromosome segreg
ation, and an increase in anucleated cell formation, There are two sim
ple explanations for the observed phenotype: induction of the SOS resp
onse or of the heat shock response, The data presented here show that
overproduction of Tnp neither induces an SOS response nor a strong hea
t shock response, However, our experiments do indicate that induction
of some sigma(32)-programmed function(s) (either due to an rpoH mutati
on, a deletion of dnaK, or overproduction of sigma(32)) suppresses Tnp
overproduction killing. This effect is not due to overproduction of D
naK, DnaJ, or GroELS. In addition, Tnp but not Delta 11 Tnp (whose ove
rproduction does not kill the host cells) associates with the inner ce
ll membrane, suggesting a possible correlation between cell killing an
d Tnp membrane association. These observations will he discussed in th
e context of a model proposing that Tnp overproduction titrates an ess
ential host factor(s) involved in an early cell division step and/or c
hromosome segregation.