A tripartite mechanism licenses RNA polymerase import into the phage nucleus
- 1UCSF
Abstract
Nucleus-forming jumbo phages import a phage-encoded non-virion RNA polymerase (nvRNAP) into a proteinaceous nucleus, but how it is selected for import is unknown. Here, we identify an import pathway that couples nvRNAP subunit interactions with phage-encoded import factors. Maximal nvRNAP import requires a novel factor Imp7 (gp166) and the essential import factor Imp1. Imp7 is essential at environmental temperatures (20 C), where impaired nvRNAP import causes a profound loss of middle and late transcription and blocks phage DNA replication. Import of individual nvRNAP subunits also depends on other subunits, consistent with import licensing at the level of an assembled complex. In the absence of middle transcription and DNA replication, the phage nucleus surprisingly still assembles and segregates from the cytoplasm, demonstrating that nvRNAP nuclear localization and activity are not a critical checkpoint for nucleus assembly. Together, these findings define a specialized pathway for nuclear import of the multi-subunit RNAP and reveal that nuclear compartment assembly precedes the transcriptional and replicative programs required for its maturation.
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BibTeX
@misc{kokontis2026tripartite,
title = {{A tripartite mechanism licenses RNA polymerase import into the phage nucleus}},
author = {C. Kokontis and D. Mozumdar and D. Chen and I. Zheng and W.-X. Yee and D. Bulkley and D. Agard and J. Bondy-Denomy},
howpublished = {bioRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.21.753271},
url = {https://www.biorxiv.org/content/10.64898/2026.09.21.753271v1},
note = {CC BY-NC},
}
RIS
TY - UNPB
TI - A tripartite mechanism licenses RNA polymerase import into the phage nucleus
AU - C. Kokontis
AU - D. Mozumdar
AU - D. Chen
AU - I. Zheng
AU - W.-X. Yee
AU - D. Bulkley
AU - D. Agard
AU - J. Bondy-Denomy
PY - 2026
DA - 2026/09/21
PB - bioRxiv
DO - 10.64898/2026.09.21.753271
UR - https://www.biorxiv.org/content/10.64898/2026.09.21.753271v1
AB - Nucleus-forming jumbo phages import a phage-encoded non-virion RNA polymerase (nvRNAP) into a proteinaceous nucleus, but how it is selected for import is unknown. Here, we identify an import pathway that couples nvRNAP subunit interactions with phage-encoded import factors. Maximal nvRNAP import requires a novel factor Imp7 (gp166) and the essential import factor Imp1. Imp7 is essential at environmental temperatures (20 C), where impaired nvRNAP import causes a profound loss of middle and late transcription and blocks phage DNA replication. Import of individual nvRNAP subunits also depends on other subunits, consistent with import licensing at the level of an assembled complex. In the absence of middle transcription and DNA replication, the phage nucleus surprisingly still assembles and segregates from the cytoplasm, demonstrating that nvRNAP nuclear localization and activity are not a critical checkpoint for nucleus assembly. Together, these findings define a specialized pathway for nuclear import of the multi-subunit RNAP and reveal that nuclear compartment assembly precedes the transcriptional and replicative programs required for its maturation.
ER -