3P9Y: Crystal structure of the Drosophila melanogaster Ssu72-pCTD complex

Citation:
Abstract
RNA polymerase II coordinates co-transcriptional events by recruiting distinct sets of nuclear factors to specific stages of transcription via changes of phosphorylation patterns along its C-terminal domain (CTD). Although it has become increasingly clear that proline isomerization also helps regulate CTD-associated processes, the molecular basis of its role is unknown. Here, we report the structure of the Ser(P)(5) CTD phosphatase Ssu72 in complex with substrate, revealing a remarkable CTD conformation with the Ser(P)(5)-Pro(6) motif in the cis configuration. We show that the cis-Ser(P)(5)-Pro(6) isomer is the minor population in solution and that Ess1-catalyzed cis-trans-proline isomerization facilitates rapid dephosphorylation by Ssu72, providing an explanation for recently discovered in vivo connections between these enzymes and a revised model for CTD-mediated small nuclear RNA termination. This work presents the first structural evidence of a cis-proline-specific enzyme and an unexpected mechanism of isomer-based regulation of phosphorylation, with broad implications for CTD biology.
PDB ID: 3P9YDownload
MMDB ID: 164135
PDB Deposition Date: 2010/10/18
Updated in MMDB: 2018/07
Experimental Method:
x-ray diffraction
Resolution: 2.1  Å
Source Organism:
Drosophila melanogaster
Similar Structures:
Biological Unit for 3P9Y: dimeric; determined by author and by software (PISA)
Molecular Components in 3P9Y
Label Count Molecule
Proteins (2 molecules)
1
Cg14216
Molecule annotation
1
Pser5 CTD Peptide
Molecule annotation
Chemicals (3 molecules)
1
2
2
1
* Click molecule labels to explore molecular sequence information.

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