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The role of Helicobacter pylori DnaA domain I in orisome assembly on a bipartite origin of chromosome replication
Author(s) -
NowaczykCieszewska Malgorzata,
ZylaUklejewicz Dorota,
Noszka Mateusz,
Jaworski Pawel,
Mielke Thorsten,
Zawilak-Pawlik Anna Magdalena
Publication year - 2020
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.14423
Subject(s) - dnaa , seqa protein domain , biology , dna replication , origin of replication , dna , circular bacterial chromosome , genetics , bipartite graph , replisome , microbiology and biotechnology , dna binding protein , computational biology , gene , computer science , transcription factor , theoretical computer science , graph
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.