8VOS

Escherichia coli transcription-translation loosely coupled complex (TTC-LC) containing mRNA with a 60 nt long spacer, NusG, NusA, and fMet-tRNAs in E-site and P-site

This is a non-PDB format compatible entry.

Summary for 8VOS

• Entry DOI: 10.2210/pdb8vos/pdb
• EMDB information: 43391
• Descriptor: Ribosomal protein L21, E-site and P-site tRNA (fMet), DNA-directed RNA polymerase subunit beta, ... (68 entities in total)
• Functional Keywords: transcription, translation, coupling, nusg, nusa, ops, ttc
• Biological source: Escherichia coli; More
• Total number of polymer chains: 68
• Total formula weight: 2806388.39

Authors

Molodtsov, V.,Wang, C.,Ebright, R.H. (deposition date: 2024-01-15, release date: 2025-07-23, Last modification date: 2026-06-24)

Primary citation

Wang, C.,Molodtsov, V.,Shandilya, S.,You, L.,Zhang, J.,Kuznedelov, K.,Nickels, B.E.,Kaelber, J.T.,Blaha, G.,Ebright, R.H.
Structural basis of long-range transcription-translation coupling.
Proc.Natl.Acad.Sci.USA, 123:e2528970123-e2528970123, 2026

PubMed Abstract: Structures recently have been reported of molecular assemblies that mediate transcription-translation coupling in . 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.

PubMed: 42268877
DOI: 10.1073/pnas.2528970123

Experimental method

ELECTRON MICROSCOPY (4.6 Å)