Topoisomerase I Essentiality, DnaA-Independent Chromosomal Replication, and Transcription-Replication Conflict in Escherichia coli.

ABSTRACT: Topoisomerase I (Topo I) of Escherichia coli, encoded by topA, acts to relax negative supercoils in DNA. Topo I deficiency results in hypernegative supercoiling, formation of transcription-associated RNA-DNA hybrids (R-loops), and DnaA- and oriC-independent constitutive stable DNA replication (cSDR), but some uncertainty persists as to whether topA is essential for viability in E. coli and related enterobacteria. Here, we show that several topA alleles, including ΔtopA, confer lethality in derivatives of wild-type E. coli strain MG1655. Viability in the absence of Topo I was restored with two perturbations, neither of which reversed the hypernegative supercoiling phenotype: (i) in a reduced-genome strain (MDS42) or (ii) by an RNA polymerase (RNAP) mutatio

SUBMITTER: Leela JK 

PROVIDER: S-EPMC8351630 | biostudies-literature | 2021 Aug

REPOSITORIES: biostudies-literature