biostudies-literatureAkiyama KMEXT | Japan Society for the Promotion of ScienceMEXT | Japan Society for the Promotion of Science (JSPS)79https://www.ebi.ac.uk/biostudies/studies/S-EPMC12820191biostudies-literatureUnknown9(1)The bacterial condensin MukB facilitates proper chromosome segregation in Escherichia coli. MukB protein localizes at the ori adjacent region by unknown mechanism. The MukB protein entraps the single-stranded DNA (ssDNA) molecule more efficiently than double-stranded DNA (dsDNA). In the bacterial genome, several copies of the rrn genes are encoded near the ori region. The rrn regions are expected to efficiently generate ssDNA due to their high transcriptional activity and the frequent formation of R-loops. In this study, we identified residues involved in DNA binding. The mutations impaired ssDNA binding more severely than dsDNA binding in vitro, and also caused deficiencies in cell growth and nucleoid segregation. These amino acid residues are aligned and are thought to bind DNA when the Communications biologyInvolvement of the inner surface residues of bacterial SMC protein MukB in the ssDNA binding in vitro.PMC12820191JP22K15086JP18H02485JP23H02525Niki HAkiyama KYano KfalseInvolvement of the inner surface residues of bacterial SMC protein MukB in the ssDNA binding in vitro.The bacterial condensin MukB facilitates proper chromosome segregation in Escherichia coli. MukB protein localizes at the ori adjacent region by unknown mechanism. The MukB protein entraps the single-stranded DNA (ssDNA) molecule more efficiently than double-stranded DNA (dsDNA). In the bacterial genome, several copies of the rrn genes are encoded near the ori region. The rrn regions are expected to efficiently generate ssDNA due to their high transcriptional activity and the frequent formation of R-loops. In this study, we identified residues involved in DNA binding. The mutations impaired ssDNA binding more severely than dsDNA binding in vitro, and also caused deficiencies in cell growth and nucleoid segregation. These amino acid residues are aligned and are thought to bind DNA when the 2025-01-01T00:00:00Z2025 Dec2026-06-14T05:07:10.65Z2026-06-14T03:09:23.754ZS-EPMC128201914140252610.1038/s42003-025-09345-5