FIG 1.

Phylogenetic tree of the ORC protein family. A consensus tree that was generated by neighbor joining after 1,000 bootstrap replications is shown. The bootstrap values (percent) are indicated at the respective nodes. The 12 ORC proteins of this study are colored as follows: the six proteins encoded adjacent to origin repeats are shown in red, and the 12 proteins encoded elsewhere are shown in blue. The essential ORC proteins of Hfx. volcanii, Hbt. salinarum, and Ha. hispanica are underlined and marked with an arrow. The seven nodes that define ORC paralogs that were already present in the common ancestor of Hfx. volcanii, Hbt. salinarum, Har. hispanica, and N. magadii are marked by a circle and are numbered. The nodes that define two ORC paralogs that predated the evolution of the Halobacteriaceae are boxed. The orc gene that could not be analyzed is marked with an asterisk.