Modelling the evolution of the archaeal tryptophan synthase

Table 2 Classifying known archaeal genomes according to the occurrence of trpB genes

S2(3), s2(1)	i2_o2(5)	i1_o2(10)	i1_o1(1)	S1(1), s1(5)
S. acidocaldarius, s2C 3, TA T. volcanium, S2E 3, TA T. acidophilum, S2E 3, TA P. horikoshii, S2E 2, HT	A. pernix, i2C 4, o2C 2, HT P. aerophilum, i2C 3, o2C 4, HT P. torridus, i2E 2, o2E 2, TA S. solfataricus, i2C 3, o2C 3, TA S. tokodaii, i2C 3, o2C 4, TA	A. fulgidus, i1E 2, o2E 6, HT M. acetivorans, i1E 1, o2E 5, MS M. barkeri, i1E 1, o2E 4, MS M. burtonii, i1E 1, o2E 4, MS M. hungatei, i1E 1, o2E 4, MS M. mazei, i1E 1, o2E 5, MS M. thermoautotrophicus, i1E 1, o2E 3, TP P. abyssi, i1E 3, o2E 2, HT P. furiosus, i1E 3, o2E 2, HT T. kodakaraensis, i1E 2, o2E 2, HT	N. pharaonis, i1E 1, o1E 0, HP	M. kandleri, S1E 4, YP Halobacterium, s1E 1, HP H. marismortui, s1E 1, HP M. maripaludis, s1E 1, MS M. stadtmanae, s1E 1, MS M. jannaschii, s1E 2, YP
2.75	i2: 3.0, o2: 3.0	i1: 1.6, o2: 3.7	i1: 1.0, o1: 0.0	1.6

Note: The occurrence and the location of trpB genes were coded according to the following scheme used in the top line: S2 species possess exactly one, non operon-based trpB2 gene, s2: ditto, the gene is located inside the trp operon. trpB1 was treated analogously. i2_o2 are species possessing an trpB2 gene inside and a second trpB2 outside the operon, i1_o2 are species with an operon-based trpB1 and a non operon-based trpB2, and i1_o1 are species possessing an operon-based and at least one non operon-based trpB1. The number of genomes having the same species-type is given in brackets. The acronyms following the species name classify trpB genes; see Results. Numbers give tryptophan codons occurring in the respective gene. The abbreviations indicate hyperthermophilic (HT), thermoacidophilic (TA), thermophilic (TP), mesophilic (MS), halophilic (HP), or hyperthermophilic + halophilic species (YP). The last line of the table gives mean values for the occurrence of tryptophan codons.