The role of Helicobacter pylori DnaA domain I in orisome assembly on a bipartite origin of chromosome replication. Issue 2 (5th December 2019)

• Record Type: Journal Article
• Authors: Nowaczyk‐Cieszewska, Malgorzata; Zyla‐Uklejewicz, Dorota; Noszka, Mateusz; Jaworski, Pawel; Mielke, Thorsten; Zawilak-Pawlik, Anna Magdalena
• Is Part Of: Molecular microbiology. Volume 113:Issue 2(2019)
• Page Start: 338
• Page End: 355
• Publication Date: 2019-12-05
• Subjects: DnaA -- HobA -- initiation of chromosome replication -- oriC -- replication initiation complex; Molecular microbiology -- Periodicals; 572.829
• DOI: 10.1111/mmi.14423
• Languages: English
• ISSNs: 0950-382X

Abstract

Abstract: The main roles of the DnaA protein are to bind the origin of chromosome replication ( oriC ), to unwind DNA and to provide a hub for the step‐wise assembly of a replisome. DnaA is composed of four domains, with each playing a distinct functional role in the orisome assembly. Out of the four domains, the role of domain I is the least understood and appears to be the most species‐specific. To better characterise Helicobacter pylori DnaA domain I, we have constructed a series of DnaA variants and studied their interactions with H. pylori bipartite oriC . We show that domain I is responsible for the stabilisation and organisation of DnaA‐ oriC complexes and provides cooperativity in DnaA–DNA interactions. Domain I mediates cross‐interactions between oriC subcomplexes, which indicates that domain I is important for long‐distance DnaA interactions and is essential for orisosme assembly on bipartite origins. HobA, which interacts with domain I, increases the DnaA binding to bipartite oriC ; however, it does not stimulate but rather inhibits DNA unwinding. This suggests that HobA helps DnaA to bind oriC, but an unknown factor triggers DNA unwinding. Together, our results indicate that domain I self‐interaction is important for the DnaA assembly on bipartite H. pylori oriC. Abstract : DnaA is composed of four domains, with each playing a distinct functional role in the orisome assembly. The role of domain I appears to be the most species‐specific. We show that H. pylori DnaA domain I is responsible for the stabilisation and organisation of DnaA‐ oriC complexes. Domain I also mediates cross‐interactions between oriC sub‐complexes, which indicates that domain I is important for long‐distance DnaA interactions and is essential for oriosme assembly on bipartite origins.