title: The histidine operon is ancient.
authors.forename: Morgan N
authors.initials: MN
authors.lastname: Price
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Alm
authors.forename: Adam P
authors.initials: AP
authors.lastname: Arkin
mesh_terms: D006639:Histidine / Q000235:genetics*; D009876:Operon / Q000235:genetics*; D010802:Phylogeny; D020560:Proteobacteria / Q000235:genetics*; D013995:Time
chemical_list: D006639:Histidine