Dataset Information

Photo-crosslinking mass spectrometry localises SNAPC5 and SNAPC2 in SNAPc

ABSTRACT: RNA polymerase III (Pol III) is specialized in the transcription of short, functional RNAs, including small nuclear RNAs (snRNAs). At snRNA genes, Pol III is recruited by the snRNA Activating Protein Complex (SNAPc)forming apreinitiation complex (PIC). Uniquely, SNAPc forms PICs with both Pol II and Pol IIIat their respectivepromoters. Increasingly, snRNA PIC structures arethe focus of structural characterization, however the mechanism of SNAPc cross-polymerase engagementand the role of the SNAPC2 and SNAPC5 subunits in transcription remain unclear. Here, we present CryoEM structuresoftheSNAPc-containing Pol III PIC assembled on the U6 snRNA promoterin the open and melting statesat 3.2-4.2Å resolution. Comparative structural analysis revealedunexpected differences with the corresponding yeast complex and revealedthe basis of SNAPc engagement with both Pol III and Pol IIPICs. Integrating crosslinkingmass spectrometry,we alsolocalizethe SNAPC2 and SNAPC5 subunitsin proximity to the bound promoter DNA, expanding upon existing descriptions of snRNA Pol III PIC structure.

INSTRUMENT(S): Orbitrap Eclipse

ORGANISM(S): Homo Sapiens (human)

SUBMITTER: Andrea Graziadei

LAB HEAD: Andrea Graziadei

PROVIDER: PXD053341 | Pride | 2025-01-06

REPOSITORIES: Pride

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Dataset's files

Source:

			Action	DRS
	240306_SNAPc_FL_contaminants.fasta	Fasta
	240306_Syed_SNAPCDNA_boostBetween_nocons.mzid.gz	Mzid
	240306_Syed_SNAPCDNA_boostBetween_nocons_Links_xiFDR2.1.5.2.csv	Csv
	240306_Syed_SNAPCDNA_boostBetween_nocons_summary_xiFDR2.1.5.2.csv	Csv
	E240306_01_HT_100_Syed_SNAPCflDNA_SDA_SECA5_inj1.raw	Raw

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Publications

Structural insights into distinct mechanisms of RNA polymerase II and III recruitment to snRNA promoters.

Shah Syed Zawar SZ Perry Thomas N TN Graziadei Andrea A Cecatiello Valentina V Kaliyappan Thangavelu T Misiaszek Agata D AD Müller Christoph W CW Ramsay Ewan P EP Vannini Alessandro A

Nature communications 20250102 1

RNA polymerase III (Pol III) transcribes short, essential RNAs, including the U6 small nuclear RNA (snRNA). At U6 snRNA genes, Pol III is recruited by the snRNA Activating Protein Complex (SNAPc) and a Brf2-containing TFIIIB complex, forming a pre-initiation complex (PIC). Uniquely, SNAPc also recruits Pol II at the remaining splicesosomal snRNA genes (U1, 2, 4 and 5). The mechanism of SNAPc cross-polymerase engagement and the role of the SNAPC2 and SNAPC5 subunits remain poorly defined. Here, w ...[more]

PMID: 39747245

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