8DTQ

Crystal Structure of Staphylococcus aureus pSK41 Cop

Summary for 8DTQ

• Entry DOI: 10.2210/pdb8dtq/pdb
• Descriptor: Helix-turn-helix domain, CHLORIDE ION, SODIUM ION, ... (4 entities in total)
• Functional Keywords: transcriptional regulator, conjugation, dna binding protein
• Biological source: Staphylococcus aureus
• Total number of polymer chains: 2
• Total formula weight: 21473.81

Authors

Walton, W.G.,Eakes, T.C.,Redinbo, M.R.,McLaughlin, K.J. (deposition date: 2022-07-26, release date: 2023-08-02, Last modification date: 2023-12-06)

Primary citation

Sarosh, A.,Kwong, S.M.,Jensen, S.O.,Northern, F.,Walton, W.G.,Eakes, T.C.,Redinbo, M.R.,Firth, N.,McLaughlin, K.J.
pSK41/pGO1-family conjugative plasmids of Staphylococcus aureus encode a cryptic repressor of replication.
Plasmid, 128:102708-102708, 2023

PubMed Abstract: The majority of large multiresistance plasmids of Staphylococcus aureus utilise a RepA_N-type replication initiation protein, the expression of which is regulated by a small antisense RNA (RNAI) that overlaps the rep mRNA leader. The pSK41/pGO1-family of conjugative plasmids additionally possess a small (86 codon) divergently transcribed ORF (orf86) located upstream of the rep locus. The product of pSK41 orf86 was predicted to have a helix-turn-helix motif suggestive of a likely function in transcriptional repression. In this study, we investigated the effect of Orf86 on transcription of thirteen pSK41 backbone promoters. We found that Orf86 only repressed transcription from the rep promoter, and hence now redesignate the product as Cop. Over-expression of Cop in trans reduced the copy number of pSK41 mini-replicons, both in the presence and absence of rnaI. in vitro protein-DNA binding experiments with purified 6 × His-Cop demonstrated specific DNA binding, adjacent to, and partially overlapping the -35 hexamer of the rep promoter. The crystal structure of Cop revealed a dimeric structure similar to other known transcriptional regulators. Cop mRNA was found to result from "read-through" transcription from the strong RNAI promoter that escapes the rnaI terminator. Thus, P is responsible for transcription of two distinct negative regulators of plasmid copy number; the antisense RNAI that primarily represses Rep translation, and Cop protein that can repress rep transcription. Deletion of cop in a native plasmid did not appear to impact copy number, indicating a cryptic auxiliary role.

PubMed: 37967733
DOI: 10.1016/j.plasmid.2023.102708

Experimental method

X-RAY DIFFRACTION (1.45 Å)