Novel chromosome organization pattern in actinomycetales-overlapping replication cycles combined with diploidy

Abstract

Bacteria regulate chromosome replication and segregation tightly with cell division to ensure faithful segregation of DNA to daughter generations. The underlying mechanisms have been addressed in several model species. It became apparent that bacteria have evolved quite different strategies to regulate DNA segregation and chromosomal organization. We have investigated here how the actinobacterium Corynebacterium glutamicum organizes chromosome segregation and DNA replication. Unexpectedly, we find that C. glutamicum cells are at least diploid under all conditions tested and that these organisms have overlapping C-periods during replication with both origins initiating replication simultaneously. Based on experimentally obtained data we propose growth rate dependent cell cycle models for C. glutamicum.