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Structures reveal DnaA domain I dimer conserved across Actinomycetes: implications for replication initiation

ABSTRACT: DNA replication is a fundamental process in biology with initiation marking its key, first step. In bacteria, DNA replication is initiated by the DnaA protein. DnaA exhibits multidomain architecture, consisting of an N-terminal domain I, linker region, AAA+ family ATPase cassette, and C-terminal DNA-binding motif. Taxon-specific regulatory functions are primarily coordinated by the DnaA domain I, which exhibits substantial sequence variation across bacteria. Notably, although the DnaA domain I has been shown to be essential, its contributions to initiation are not completely understood. Importantly, studies have indicated a role for DnaA domain I dimerization in the cooperative assembly of the initiation complex at the origin. However, the mechanism(s) and molecular basis of DnaA domain I dimerization have proved elusive. Here, we report structures of the DnaA domain I from ten Actinobacterial species. Strikingly, all structures reveal the same, unique dimer, and key elements which support DnaA domain I self-interaction are broadly conserved across the class Actinomycetes. Further, a suite of biochemical oligomerization assays and HDX-MS studies support the structural dimer. These findings suggest weak dimerization, as mediated by the DnaA domain I, acts a fine-tuned trigger in cooperative oriC assembly and that this is a broadly conserved biological mechanism for replication initiation in the class Actinomycetes.

INSTRUMENT(S):

ORGANISM(S): Homo Sapiens (human)

SUBMITTER: Thomas Wales

LAB HEAD: Thomas E. Wales

PROVIDER: PXD074705 | Pride | 2026-05-27

REPOSITORIES: Pride

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			Action	DRS
	1_Rhoagii_HighConc_10m1.raw.zip	Raw
	1_Rhoagii_HighConc_10m2.raw.zip	Raw
	1_Rhoagii_HighConc_10s1.raw.zip	Raw
	1_Rhoagii_HighConc_10s2.raw.zip	Raw
	1_Rhoagii_HighConc_1h1.raw.zip	Raw

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Structures reveal DnaA domain I dimer conserved across Actinomycetes: implications for replication initiation

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