This family, many of whose members are YcbG, organizes the macrodomain Ter of the chromosome of bacteria such as E coli. In these bacteria, insulated macrodomains influence the segregation of sister chromatids and the mobility of chromosomal DNA. Organisation of the Terminus region (Ter) into a macrodomain relies on the presence of a 13 bp motif called matS repeated 23 times in the 800-kb-long domain. MatS sites are the main targets in the E. coli chromosome of YcbG or MatP (macrodomain Ter protein). MatP accumulates in the cell as a discrete focus that co-localizes with the Ter macrodomain. The effects of MatP inactivation reveal its role as the main organizer of the Ter macrodomain: in the absence of MatP, DNA is less compacted, the mobility of markers is increased, and segregation of the Ter macrodomain occurs early in the cell cycle. A specific organisational system is required in the Terminus region for bacterial chromosome management during the cell cycle. This entry represents the N-terminal domain of MatP.