Structural highlights
Function
NOC_BACSU Effects nucleoid occlusion by binding relatively nonspecifically to DNA and preventing the assembly of the division machinery in the vicinity of the nucleoid, especially under conditions that disturb the cell cycle. It helps to coordinate cell division and chromosome segregation by preventing the formation of the Z ring through the nucleoid, which would cause chromosome breakage.[1]
Publication Abstract from PubMed
In Bacillus subtilis, a ParB-like nucleoid occlusion protein (Noc) binds specifically to Noc-binding sites (NBS) on the chromosome to help coordinate chromosome segregation and cell division. Noc does so by binding to cytidine triphosphate (CTP) to form large membrane-associated nucleoprotein complexes to physically inhibit the assembly of the cell division machinery. The site-specific binding of Noc to NBS DNA is a prerequisite for CTP-binding and the subsequent formation of a membrane-active DNA-entrapped protein complex. Here, we solve the structure of a C-terminally truncated B. subtilis Noc bound to NBS DNA to reveal the conformation of Noc at this crucial step. Our structure reveals the disengagement between the N-terminal CTP-binding domain and the NBS-binding domain of each DNA-bound Noc subunit, this is driven, in part, by the swapping of helices 4 and 5 at the interface of the two domains. Site-specific crosslinking data suggest that this conformation of Noc-NBS exists in solution. Overall, our results lend support to the recent proposal that parS/NBS-binding catalyzes CTP-binding and DNA-entrapment by preventing the re-engagement of the CTP-binding domain and the DNA-binding domain from the same ParB/Noc subunit.
The CTP-binding domain is disengaged from the DNA-binding domain in a co-crystal structure of Bacillus subtilis Noc-DNA complex.,Sukhoverkov K, Jalal AB, Ault J, Sobott F, Lawson D, Le TK J Biol Chem. 2023 Feb 23:103063. doi: 10.1016/j.jbc.2023.103063. PMID:36841481[2]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Wu LJ, Errington J. Coordination of cell division and chromosome segregation by a nucleoid occlusion protein in Bacillus subtilis. Cell. 2004 Jun 25;117(7):915-25. PMID:15210112 doi:10.1016/j.cell.2004.06.002
- ↑ Sukhoverkov KV, Jalal ASB, Ault JR, Sobott F, Lawson DM, Le TBK. The CTP-binding domain is disengaged from the DNA-binding domain in a cocrystal structure of Bacillus subtilis Noc-DNA complex. J Biol Chem. 2023 Apr;299(4):103063. PMID:36841481 doi:10.1016/j.jbc.2023.103063
