Tetramerization and interdomain flexibility of the replication initiation controller YabA enables simultaneous binding to multiple partners

Liza Felicori, Katie H. Jameson, Pierre Roblin, Mark J. Fogg, Transito Garcia-Garcia, Magali Ventroux, Mickaël V. Cherrier, Alexandre Bazin, Philippe Noirot, Anthony J. Wilkinson, Franck Molina*, Laurent Terradot, Marie Françoise Noirot-Gros

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


YabA negatively regulates initiation of DNA replication in low-GC Gram-positive bacteria. The protein exerts its control through interactions with the initiator protein DnaA and the sliding clamp DnaN. Here, we combined X-ray crystallography, X-ray scattering (SAXS), modeling and biophysical approaches, with in vivo experimental data to gain insight into YabA function. The crystal structure of the N-terminal domain (NTD) of YabA solved at 2.7 Å resolution reveals an extended α-helix that contributes to an intermolecular four-helix bundle. Homology modeling and biochemical analysis indicates that the C-terminal domain (CTD) of YabA is a small Zn-binding domain. Multi-angle light scattering and SAXS demonstrate that YabA is a tetramer in which the CTDs are independent and connected to the N-terminal four-helix bundle via flexible linkers. While YabA can simultaneously interact with both DnaA and DnaN, we found that an isolated CTD can bind to either DnaA or DnaN, individually. Site-directed mutagenesis and yeast-two hybrid assays identified DnaA and DnaN binding sites on the YabA CTD that partially overlap and point to a mutually exclusive mode of interaction. Our study defines YabA as a novel structural hub and explains how the protein tetramer uses independent CTDs to bind multiple partners to orchestrate replication initiation in the bacterial cell.

Original languageEnglish
Pages (from-to)450-463
Number of pages13
JournalNucleic Acids Research
Issue number1
Early online date28 Nov 2015
Publication statusPublished - 8 Jan 2016

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