Conserved genomic context of three DNA replication genes in archaeal genomes. This figure highlights the genome context of three DNA replication genes that recurrently associate with a particular set of genes in archaeal genomes (for a detailed picture of the genome context of all DNA replication genes examined in this study see Additional data file 2). (a) The gene encoding Gins15 is linked to the gene coding for PCNA and to the gene for the small subunit of the primase in all crenarchaeal genomes, whereas it is alternatively linked to one of these two genes in most euryarchaeal genomes. (b) The gene for the PCNA associates with the genes encoding the small or the large subunit of the DNA primase. It is also frequently linked to the gene encoding TFS and/or to the gene coding for the ADP-ribose pyrophosphatase NudF. (c) The gene encoding the MCM helicase is contiguous to the gene for Gins23 and/or to the gene for the beta subunit of the initiation factor aIF-2 in several archaeal genomes. Orthologous genes are indicated in the same color. Each gene is denoted by the name of the protein it encodes (see the key at the bottom). Species or cell lineages that have the same genomic environment are listed and the number of corresponding genomes is given in parentheses. White arrows correspond to additional functionally unrelated genes. Genes are not shown to scale.