The information transfer system of halophilic archaea.

Information transfer is fundamental to all life forms. In the third domain of life, the archaea, many of the genes functioning in these processes are similar to their eukaryotic counterparts, including DNA replication and repair, basal transcription, and translation genes, while many transcriptional regulators and the overall genome structure are more bacterial-like. Among halophilic (salt-loving) archaea, the genomes commonly include extrachromosomal elements, many of which are large megaplasmids or minichromosomes.

Multiple replication origins of Halobacterium sp. strain NRC-1: properties of the conserved orc7-dependent oriC1.

The eukaryote-like DNA replication system of the model haloarchaeon Halobacterium NRC-1 is encoded within a circular chromosome and two large megaplasmids or minichromosomes, pNRC100 and pNRC200. We previously showed by genetic analysis that 2 (orc2 and orc10) of the 10 genes coding for Orc-Cdc6 replication initiator proteins were essential, while a third (orc7), located near a highly conserved autonomously replicating sequence, oriC1, was nonessential for cell viability. Here we used whole-genome marker frequency analysis (MFA) and found multiple peaks, indicative of multiple replication origins.