A lethal ORC ATPase mutation is suppressed by alterations in ORC and RNA Pol II transcription components
- 1Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, United States of America
- 2Howard Hughes Medical Institute, Cambridge, MA, United States of America
Abstract
The origin recognition complex (ORC) binds origins of replication and directs the loading of the Mcm2–7 replicative helicase at these sites. Five of the six ORC subunits are related to the AAA+ family of ATPases. Although functions for ATP hydrolysis by Cdc6 and the Mcm2–7 complex have been described, the essential role of ORC ATP hydrolysis remains unclear. We performed a genetic screen in Saccharomyces cerevisiae for suppressors of the lethal phenotype of the orc4-R267A allele, which disrupts ORC ATP hydrolysis in vitro. We identified six causative mutations, five of which are distributed across different ORC subunits. The suppressor mutations in Orc1 and Orc4, but not those in other ORC subunits, increase the in vitro helicase loading activity of ATPase-defective ORC (ORC4R). Allele specificity studies show the alleles specifically suppress defects at ATPase interfaces within the ORC-Cdc6 complex. The sixth allele is a mutation in TOA2, a subunit of the TFIIA general transcription factor. Mutations in the general transcription factors TBP and TFIIB, and the large subunit of RNA Polymerase II also suppress orc4-R267A lethality, suggesting that reducing transcription is sufficient for suppression. Our study identifies multiple pathways to suppress the lethal phenotype of an ATPase-defective ORC allele and reveals a connection between ORC ATP hydrolysis and transcription.
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BibTeX
@article{martinezrodriguez2026lethal,
title = {{A lethal ORC ATPase mutation is suppressed by alterations in ORC and RNA Pol II transcription components}},
author = {Luis E. Martínez-Rodríguez and Stephen P. Bell},
journal = {PLOS One},
year = {2026},
month = sep,
doi = {10.1371/journal.pone.0349465},
url = {https://doi.org/10.1371/journal.pone.0349465},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - A lethal ORC ATPase mutation is suppressed by alterations in ORC and RNA Pol II transcription components
AU - Luis E. Martínez-Rodríguez
AU - Stephen P. Bell
PY - 2026
DA - 2026/09/30
JO - PLOS One
DO - 10.1371/journal.pone.0349465
UR - https://doi.org/10.1371/journal.pone.0349465
AB - The origin recognition complex (ORC) binds origins of replication and directs the loading of the Mcm2–7 replicative helicase at these sites. Five of the six ORC subunits are related to the AAA+ family of ATPases. Although functions for ATP hydrolysis by Cdc6 and the Mcm2–7 complex have been described, the essential role of ORC ATP hydrolysis remains unclear. We performed a genetic screen in Saccharomyces cerevisiae for suppressors of the lethal phenotype of the orc4-R267A allele, which disrupts ORC ATP hydrolysis in vitro. We identified six causative mutations, five of which are distributed across different ORC subunits. The suppressor mutations in Orc1 and Orc4, but not those in other ORC subunits, increase the in vitro helicase loading activity of ATPase-defective ORC (ORC4R). Allele specificity studies show the alleles specifically suppress defects at ATPase interfaces within the ORC-Cdc6 complex. The sixth allele is a mutation in TOA2, a subunit of the TFIIA general transcription factor. Mutations in the general transcription factors TBP and TFIIB, and the large subunit of RNA Polymerase II also suppress orc4-R267A lethality, suggesting that reducing transcription is sufficient for suppression. Our study identifies multiple pathways to suppress the lethal phenotype of an ATPase-defective ORC allele and reveals a connection between ORC ATP hydrolysis and transcription.
SN - 1932-6203
ER -