Plasmid RK2 ParB preferentially cleaves single-stranded DNA. ParB also nicks supercoiled plasmid DNA preferably at sites with potential single-stranded character, like AT-rich regions and sequences that can form cruciform structures. ParB also exhibits 5-->3 exonuclease activity.
Proteins containing this domain include Escherichia coli plasmid protein ParB and mammalian Sulfiredoxin-1.
ParB is involved in chromosome partition. It localize to both poles of the predivisional cell following completion of DNA replication [ (PUBMED:12603730) ].
Sulfiredoxin-1 contributes to oxidative stress resistance by reducing cysteine-sulfinic acid formed under exposure to oxidants in the peroxiredoxins PRDX1, PRDX2, PRDX3 and PRDX4 [ (PUBMED:15448164) ].
Family alignment:
There are 42513 ParB domains in 42476 proteins in SMART's nrdb database.
Click on the following links for more information.
Evolution (species in which this domain is found)
Taxonomic distribution of proteins containing ParB domain.
This tree includes only several representative species. The complete taxonomic breakdown of all proteins with ParB domain is also avaliable.
Click on the protein counts, or double click on taxonomic names to display all proteins containing ParB domain in the selected taxonomic class.
Literature (relevant references for this domain)
Primary literature is listed below; Automatically-derived, secondary literature is also avaliable.
Plasmid RK2 ParB protein: purification and nuclease properties.
J Bacteriol. 1999; 181: 6010-8
Display abstract
The parCBA operon of the 3.2-kb stabilization region of plasmid RK2 encodes three cotranslated proteins. ParA mediates site-specific recombination to resolve plasmid multimers, ParB has been shown to be a nuclease, and the function of ParC is unknown. In this study ParB was overexpressed by cotranslation with ParC in Escherichia coli by using a plasmid construct that contained the parC and parB genes under the control of the T7 promoter. Purification was achieved by treatment of extracts with Polymin P, followed by ammonium sulfate precipitation and heparin and ion-exchange chromatography. Sizing-column analysis indicated that ParB exists as a monomer in solution. Analysis of the enzymatic properties of purified ParB indicated that the protein preferentially cleaves single-stranded DNA. ParB also nicks supercoiled plasmid DNA preferably at sites with potential single-stranded character, like AT-rich regions and sequences that can form cruciform structures. ParB also exhibits 5'-->3' exonuclease activity. This ParB activity on a 5'-end-labeled, double-stranded DNA substrate produces a 3', 5'-phosphorylated dinucleotide which is further cleaved to a 3', 5'-phosphorylated mononucleotide. The role of the ParB endonuclease and exonuclease activities in plasmid RK2 stabilization remains to be determined.
spo0J is required for normal chromosome segregation as well as the initiation of sporulation in Bacillus subtilis.
J Bacteriol. 1994; 176: 5320-9
Display abstract
The spo0J gene of Bacillus subtilis is required for the initiation of sporulation. We show that the sporulation defect caused by null mutations in spo0J is suppressed by a null mutation in the gene located directly upstream from spo0J, soj (suppressor of spo0J). These results indicate that Soj inhibits the initiation of sporulation and that Spo0J antagonizes that inhibition. Further genetic experiments indicated that Soj ultimately affects sporulation by inhibiting the activation (phosphorylation) of the developmental transcription factor encoded by spo0A. In addition, the temperature-sensitive sporulation phenotype caused by the ftsA279 (spoIIN279) mutation was partly suppressed by the soj null mutation, indicating that FtsA might also affect the activity of Soj. Soj and Spo0J are known to be similar in sequence to a family of proteins involved in plasmid partitioning, including ParA and ParB of prophage P1, SopA and SopB of F, and IncC and KorB of RK2, spo0J was found to be required for normal chromosome partitioning as well as for sporulation. spo0J null mutants produced a significant proportion of anucleate cells during vegetative growth. The dual functions of Spo0J could provide a mechanism for regulating the initiation of sporulation in response to activity of the chromosome partition machinery.
Metabolism (metabolic pathways involving proteins which contain this domain)
Click the image to view the interactive version of the map in iPath
This information is based on mapping of SMART genomic protein database to KEGG orthologous groups. Percentage points are related to the number of proteins with ParB domain which could be assigned to a KEGG orthologous group, and not all proteins containing ParB domain. Please note that proteins can be included in multiple pathways, ie. the numbers above will not always add up to 100%.
