Download MendeleyStructural basis of long-range transcription-translation coupling.
Wang, C., Molodtsov, V., Shandilya, S., You, L., Zhang, J., Kuznedelov, K., Nickels, B.E., Kaelber, J.T., Blaha, G., Ebright, R.H.(2026) Proc Natl Acad Sci U S A 123: e2528970123-e2528970123
- PubMed: 42268877 Search on PubMedSearch on PubMed Central
- DOI: https://doi.org/10.1073/pnas.2528970123
- Primary Citation Related Structures:
8VKV, 8VL1, 8VOO, 8VOP, 8VOQ, 8VOR, 8VOS, 9Y79 - PubMed Abstract:
Structures recently have been reported of molecular assemblies that mediate transcription-translation coupling in Escherichia coli . In these molecular assemblies, termed "coupled transcription-translation complexes" or "TTC-B," RNA polymerase (RNAP) directly interacts with the ribosome, the transcription elongation factor NusG or its paralog RfaH forms a bridge between RNAP and ribosome, and the transcription elongation factor NusA optionally forms a second bridge between RNAP and ribosome. Here, we report structures of coupled transcription-translation complexes having mRNA spacers between RNAP and ribosome longer than the maximum-length mRNA spacer compatible with formation of TTC-B. The results define a class of coupled transcription-translation complex, termed "TTC-LC," where "LC" denotes "long-range coupling." TTC-LC differs from TTC-B by a ~60° rotation and ~70 Å translation of RNAP relative to ribosome, resulting in loss of direct interactions between RNAP and ribosome and creation of a ~70 Å gap between RNAP and ribosome. TTC-LC accommodates long mRNA spacers by looping out mRNA from the gap between RNAP and ribosome. We present evidence that TTC-LC is a functional intermediate in assembling and disassembling TTC-B, mediating pre-TTC-B transcription-translation coupling before a ribosome catches up to RNAP, and mediating post-TTC-B transcription-translation coupling after a ribosome stops moving and RNAP continues moving. We show that TTC-B, but not TTC-LC, is severely defective in RNA-hairpin-dependent transcription termination, and that both TTC-B and TTC-LC are severely defective in Rho-dependent transcription termination.
- Waksman Institute and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854.
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