5dol

Publication Abstract from PubMed

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 A resolution reveals an extended alpha-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.

Tetramerization and interdomain flexibility of the replication initiation controller YabA enables simultaneous binding to multiple partners.,Felicori L, Jameson KH, Roblin P, Fogg MJ, Garcia-Garcia T, Ventroux M, Cherrier MV, Bazin A, Noirot P, Wilkinson AJ, Molina F, Terradot L, Noirot-Gros MF Nucleic Acids Res. 2016 Jan 8;44(1):449-63. doi: 10.1093/nar/gkv1318. Epub 2015, Nov 28. PMID:26615189^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.