Initiation of DNA replication in eukaryotes: questioning the origin

Although proteins involved in DNA replication in yeast have counterparts in multicellular organisms, the definition of an origin of DNA replication an d its control in higher eukaryotes might obey to different rules. Origins o f DNA replication that are site-specific have been found, supporting the no tion that specific DNA regions are used to initiate DNA synthesis along met azoan chromosomes. However, the notion that specific sequences will define origins is still being debated. The variety and complexity of transcription al programs that have to be regulated in multicellular organisms may impose a plasticity that would not be compatible with a fixed origin simply defin ed at the sequence level, Such a plasticity would be essential to developme ntal programs where the central of DNA replication could be more integrated to the control of gene expression than in unicellular eukaryotes. (C) 1999 Federation of European Biochemical Societies.