Enterococcal PcfF Is a Ribbon-Helix-Helix Protein That Recruits the Relaxase PcfG Through Binding and Bending of the oriT Sequence

Rehman, Saima (author): Umeå universitet,Institutionen för medicinsk kemi och biofysik

Li, Yang Grace (author)

Schmitt, Andreas (author): Umeå universitet,Institutionen för medicinsk kemi och biofysik

Lassinantti, Lena (author): Umeå universitet,Institutionen för medicinsk kemi och biofysik

Christie, Peter J. (author)

Berntsson, Ronnie P. -A. (author): Umeå universitet,Institutionen för medicinsk kemi och biofysik

(creator_code:org_t)

2019-05-07
2019
English.
In: Frontiers in Microbiology. - : Frontiers Media S.A.. - 1664-302X. ; 10

Related links:: https://doi.org/10.3...; show more...; https://umu.diva-por... (primary) (Raw object); https://www.frontier...; https://urn.kb.se/re...; https://doi.org/10.3...; show less...

Abstract Subject headings

The conjugative plasmid pCF10 from Enterococcus faecalis encodes a Type 4 Secretion System required for plasmid transfer. The accessory factor PcfF and relaxase PcfG initiate pCF10 transfer by forming the catalytically active relaxosome at the plasmid’s origin-of-transfer (oriT) sequence. Here, we report the crystal structure of the homodimeric PcfF, composed of an N-terminal DNA binding Ribbon-Helix-Helix (RHH) domain and a C-terminal stalk domain. We identified key residues in the RHH domain that are responsible for binding pCF10’s oriT sequence in vitro, and further showed that PcfF bends the DNA upon oriT binding. By mutational analysis and pull-down experiments, we identified residues in the stalk domain that contribute to interaction with PcfG. PcfF variant proteins defective in oriT or PcfG binding attenuated plasmid transfer in vivo, but also suggested that intrinsic or extrinsic factors might modulate relaxosome assembly. We propose that PcfF initiates relaxosome assembly by binding oriT and inducing DNA bending, which serves to recruit PcfG as well as extrinsic factors necessary for optimal plasmid processing and engagement with the pCF10 transfer machine.

By the author/editor: Rehman, Saima; Li, Yang Grace; Schmitt, Andreas; Lassinantti, Len ...; Christie, Peter ...; Berntsson, Ronni ...

About the subject

NATURAL SCIENCES: NATURAL SCIENCES; and Biological Scien ...; and Structural Biolo ...

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