DNA polymerase III protein, HolC, helps resolve replication/transcription conflicts
In Escherichia coli, DNA replication is catalyzed by an assembly of proteins, the DNA polymerase III holoenzyme. This complex includes the polymerase and proofreading subunits, the processivity clamp and clamp loader complex. The holC gene encodes an accessory protein (known as χ) to the core clamp...
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Shared Science Publishers OG
2021-05-01
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| Online Access: | http://microbialcell.com/researcharticles/2021a-lovett-microbial-cell/ |
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| author | Susan T. Lovett |
| author_facet | Susan T. Lovett |
| author_sort | Susan T. Lovett |
| collection | DOAJ |
| description | In Escherichia coli, DNA replication is catalyzed by an assembly of proteins, the DNA polymerase III holoenzyme. This complex includes the polymerase and proofreading subunits, the processivity clamp and clamp loader complex. The holC gene encodes an accessory protein (known as χ) to the core clamp loader complex and is the only protein of the holoenzyme that binds to single-strand DNA binding protein, SSB. HolC is not essential for viability although mutants show growth impairment, genetic instability and sensitivity to DNA damaging agents. In this study we isolate spontaneous suppressor mutants in a holC∆ strain and identify these by whole genome sequencing. Some suppressors are alleles of RNA polymerase, suggesting that transcription is problematic for holC mutant strains, and of sspA, stringent starvation protein. Using a conditional holC plasmid, we examine factors affecting transcription elongation and termination for synergistic or suppressive effects on holC mutant phenotypes. Alleles of RpoA (α), RpoB (β) and RpoC (β’) RNA polymerase holoenzyme can partially suppress loss of HolC. In contrast, mutations in transcription factors DksA and NusA enhanced the inviability of holC mutants. HolC mutants showed enhanced sensitivity to bicyclomycin, a specific inhibitor of Rho-dependent termination. Bicyclomycin also reverses suppression of holC by rpoA, rpoC and sspA. An inversion of the highly expressed rrnA operon exacerbates the growth defects of holC mutants. We propose that transcription complexes block replication in holC mutants and Rho-dependent transcriptional termination and DksA function are particularly important to sustain viability and chromosome integrity. |
| format | Article |
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| institution | DOAJ |
| issn | 2311-2638 |
| language | English |
| publishDate | 2021-05-01 |
| publisher | Shared Science Publishers OG |
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| series | Microbial Cell |
| spelling | doaj-art-4fa7927f477140a1b8a277112bd5f3952025-08-20T02:57:37ZengShared Science Publishers OGMicrobial Cell2311-26382021-05-018614314510.15698/mic2021.06.753DNA polymerase III protein, HolC, helps resolve replication/transcription conflictsSusan T. Lovett0Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA.In Escherichia coli, DNA replication is catalyzed by an assembly of proteins, the DNA polymerase III holoenzyme. This complex includes the polymerase and proofreading subunits, the processivity clamp and clamp loader complex. The holC gene encodes an accessory protein (known as χ) to the core clamp loader complex and is the only protein of the holoenzyme that binds to single-strand DNA binding protein, SSB. HolC is not essential for viability although mutants show growth impairment, genetic instability and sensitivity to DNA damaging agents. In this study we isolate spontaneous suppressor mutants in a holC∆ strain and identify these by whole genome sequencing. Some suppressors are alleles of RNA polymerase, suggesting that transcription is problematic for holC mutant strains, and of sspA, stringent starvation protein. Using a conditional holC plasmid, we examine factors affecting transcription elongation and termination for synergistic or suppressive effects on holC mutant phenotypes. Alleles of RpoA (α), RpoB (β) and RpoC (β’) RNA polymerase holoenzyme can partially suppress loss of HolC. In contrast, mutations in transcription factors DksA and NusA enhanced the inviability of holC mutants. HolC mutants showed enhanced sensitivity to bicyclomycin, a specific inhibitor of Rho-dependent termination. Bicyclomycin also reverses suppression of holC by rpoA, rpoC and sspA. An inversion of the highly expressed rrnA operon exacerbates the growth defects of holC mutants. We propose that transcription complexes block replication in holC mutants and Rho-dependent transcriptional termination and DksA function are particularly important to sustain viability and chromosome integrity.http://microbialcell.com/researcharticles/2021a-lovett-microbial-cell/dna polymeraserna polymerasetranscription terminationrho |
| spellingShingle | Susan T. Lovett DNA polymerase III protein, HolC, helps resolve replication/transcription conflicts Microbial Cell dna polymerase rna polymerase transcription termination rho |
| title | DNA polymerase III protein, HolC, helps resolve replication/transcription conflicts |
| title_full | DNA polymerase III protein, HolC, helps resolve replication/transcription conflicts |
| title_fullStr | DNA polymerase III protein, HolC, helps resolve replication/transcription conflicts |
| title_full_unstemmed | DNA polymerase III protein, HolC, helps resolve replication/transcription conflicts |
| title_short | DNA polymerase III protein, HolC, helps resolve replication/transcription conflicts |
| title_sort | dna polymerase iii protein holc helps resolve replication transcription conflicts |
| topic | dna polymerase rna polymerase transcription termination rho |
| url | http://microbialcell.com/researcharticles/2021a-lovett-microbial-cell/ |
| work_keys_str_mv | AT susantlovett dnapolymeraseiiiproteinholchelpsresolvereplicationtranscriptionconflicts |