6y93

Crystal structure of the DNA-binding domain of the Nucleoid Occlusion Factor (Noc) complexed to the Noc-binding site (NBS)Crystal structure of the DNA-binding domain of the Nucleoid Occlusion Factor (Noc) complexed to the Noc-binding site (NBS)

Structural highlights

6y93 is a 4 chain structure with sequence from Bacillus subtilis subsp. subtilis str. 168 and Synthetic construct. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 2.23Å
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

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

Specific interactions between proteins and DNA are essential to many biological processes. Yet, it remains unclear how the diversification in DNA-binding specificity was brought about, and the mutational paths that led to changes in specificity are unknown. Using a pair of evolutionarily related DNA-binding proteins, each with a different DNA preference (ParB [Partitioning Protein B] and Noc [Nucleoid Occlusion Factor], which both play roles in bacterial chromosome maintenance), we show that specificity is encoded by a set of four residues at the protein-DNA interface. Combining X-ray crystallography and deep mutational scanning of the interface, we suggest that permissive mutations must be introduced before specificity-switching mutations to reprogram specificity and that mutational paths to new specificity do not necessarily involve dual-specificity intermediates. Overall, our results provide insight into the possible evolutionary history of ParB and Noc and, in a broader context, might be useful for understanding the evolution of other classes of DNA-binding proteins.

Diversification of DNA-Binding Specificity by Permissive and Specificity-Switching Mutations in the ParB/Noc Protein Family.,Jalal ASB, Tran NT, Stevenson CE, Chan EW, Lo R, Tan X, Noy A, Lawson DM, Le TBK Cell Rep. 2020 Jul 21;32(3):107928. doi: 10.1016/j.celrep.2020.107928. PMID:32698006^[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
↑ Jalal ASB, Tran NT, Stevenson CE, Chan EW, Lo R, Tan X, Noy A, Lawson DM, Le TBK. Diversification of DNA-Binding Specificity by Permissive and Specificity-Switching Mutations in the ParB/Noc Protein Family. Cell Rep. 2020 Jul 21;32(3):107928. PMID:32698006 doi:10.1016/j.celrep.2020.107928

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OCA

[1] 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

[2] Jalal ASB, Tran NT, Stevenson CE, Chan EW, Lo R, Tan X, Noy A, Lawson DM, Le TBK. Diversification of DNA-Binding Specificity by Permissive and Specificity-Switching Mutations in the ParB/Noc Protein Family. Cell Rep. 2020 Jul 21;32(3):107928. PMID:32698006 doi:10.1016/j.celrep.2020.107928

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