Table 2.
Examples of probable mosaic operons
| Species | Predicted operon | General operon function | Horizontally acquired genes | Probable source of horizontally acquired genes | Functions of horizontally acquired genes |
| Cluster 1* | |||||
| Rickettsia prowazekii Rickettsia conorii | RP633-661, RC0980-1008 | Ribosomal operon | RP651 RC0998 | Chlamydia | L29 |
| Aquifex aeolicus | Aq001-021 | Ribosomal operon | Aq018a | Archaea | L29 |
| Cluster 2 | |||||
| Rickettsia prowazekii Rickettsia conorii | RP800-804, RC1234-1238 | F0F1-type ATPase | RP804 RC1238 Gram-positive bacteria | Delta subunit | |
| Ureaplasma urealyticum | UU128-138 | F0F1-type ATPase | UU128, UU132_1, UU133, UU134 | Gram-negative bacteria | Epsilon subunit, alpha subunit, delta subunit, delta subunit |
| Mycobacterium leprae | ML1139-1146 | F0F1-type ATPase | ML1139 | Gram-negative bacteria | A chain protein |
| Cluster 3 | |||||
| Rickettsia prowazekii Rickettsia conorii | RP134-139, RC175-180 | Ribosomal proteins, transcription antiterminator, SecE | RP134 RC175 | Gram-positive bacteria | Preprotein translocase subunit SecE |
| Cluster 5 | |||||
| Aquifex aeolicus | Aq1968_1_2 two domains | Histidine biosynthesis | Gram-negative bacteria | Phosphoribosyl-AMP cyclohydrolase | |
| Cluster 8 | |||||
| Methanococcus jannaschii | MJ1037-1038 | Tryptophan biosynthesis | MJ1037 | Bacteria | Tryptophan synthase beta chain |
| Methanobacterium thermoautotrophicum | MTH1655-1661 | Tryptophan biosynthesis | MTH1660 | Gram-negative bacteria | Tryptophan synthase alpha chain |
| Halobacterium sp. | VNG0305-0309 | Tryptophan biosynthesis | VNG0307G | Bacteria | Tryptophan synthase beta chain |
| Bacillus subtilis Bacillus halodurans | PabB-folK BH0090-0095 | Tryptophan biosynthesis | PabB, BH0090 | Gram-negative bacteria | Anthranilate/para-aminobenzoate synthases component I |
| Cluster 9 | |||||
| Halobacterium sp. | VNG0635G-0647G | NADH:ubiquinone oxidoreductase | VNG0640G | Gram-negative bacteria | NADH dehydrogenase-like protein |
| Cluster 18 | |||||
| Rickettsia prowazekii Rickettsia conorii | RP423-425, RC0588-0590 | Lipid metabolism | RP425, RC0590 | Spirochetes | Undecaprenyl pyrophosphate synthase |
| Cluster 27 | |||||
| Halobacterium sp. | VNG1306G-1310G | Succinate dehydrogenase/fumarate reductase | VNG1310G | Actinobacteria | Succinate dehydrogenase subunit C |
| Cluster 29 | |||||
| Mycoplasma genitalium Mycoplasma pneumoniae | MG461-466 MPN677-682 | Housekeeping | MG466 MPN682 | Gram-negative bacteria | Ribosomal protein L34 |
| Cluster 34 | |||||
| Thermotoga maritima | TM0548-0556 | Leucine/isoleucine biosynthesis | TM0552 TM0555 TM0554 | 2-Isopropylmalate synthase 3-Isopropylmalate dehydratase, small subunit 3-Isopropylmalate dehydratase, large subunit | |
| Pyrococcus abyssi | PAB888-895 | PAB0890 PAB0893 | Bacteria | 2-Isopropylmalate synthase (LeuA-1) 3-Isopropylmalate dehydrogenase (LeuB) | |
| Clostridium acetobutylicum | CAC3169-3174 | Leucine/isoleucine biosynthesis | CAC3172 CAC3173 CAC3174 Archaea | 3-Isopropylmalate dehydratase, small subunit 3-Isopropylmalate dehydratase, large subunit 2-Isopropylmalate synthase | |
| Cluster 41 | |||||
| Thermotoga maritima | TM1243-1251 | Nucleotide metabolism | TM1243 | Archaea | Phosphoribosylaminoimidazole-succinocarboxamide synthase |
| Cluster 42 | |||||
| Lactococcus lactis | L0104-0108 | Arginine biosynthesis | L0107 | Gram-negative bacteria | Acetylglutamate kinase |
| Thermotoga maritima | TM1780-1785 | Arginine biosynthesis TM1784 | Archaea | Acetylglutamate kinase | |
| Cluster 48 | |||||
| Borrelia burgdorferi | BB0054-0061 | Carbohydrate metabolism (glycolysis, gluconeogenesis) | BB0057 | Gram-positive bacteria | Glyceraldehyde-3-phosphate dehydrogenase |
| Cluster 54 | |||||
| Thermotoga maritima | TM1780-1785 | Arginine biosynthesis | TM1780 | Gram-negative bacteria | Argininosuccinate synthase |
| Cluster 63 | |||||
| Mycoplasma pneumoniae Mycoplasma genitalium | MPN573-574 MG391-392 | Molecular chaperones | MPN574 MG393 | Gram-negative bacteria | Heat shock protein (groES) |
| Cluster 82 | |||||
| Mycoplasma pneumoniae, Mycoplasma genitalium | MPN535-536 MG358-359 | DNA replication, recombination and repair | MPN536 MG359 | Gram-negative bacteria | Holliday junction resolvasome helicase subunit |
| Ureaplasma urealyticum | UU448-449 | DNA replication, recombination and repair | UU448 | Gram-negative bacteria | Holliday junction resolvasome helicase subunit |
| Cluster 86 | |||||
| Halobacterium sp. | VNG6305CC-6306C | Tetrahydrobiopterin biosynthesis | VNG6305C | Gram-negative bacteria | Organic radical activating enzyme |
| Cluster 87 | |||||
| Halobacterium sp. | VNG0582C-0586C | Energy production and conversion | VNG0582, VNG0583G | Bacteria | Cytochrome b subunit of the bc complex Cytochrome b subunit of the bc complex |
| Cluster 103 | |||||
| Archaeoglobus fulgidus | AF0321-0325 | Lipopolysaccharide biosynthesis | AF0323b | Bacteria | dTDP-4-dehydrorhamnose 3,5-epimerase and related enzymes |
| Deinococcus radiodurans | DRA0037-DRA0044 | Lipopolysaccharide biosynthesis | DRA0044 | Archaea | dTDP-4-dehydrorhamnose epimerase |
| Methanothermobacter thermoautotrophicus | MTH1789-1792 | Lipopolysaccharide biosynthesis | MTH1789, MTH1790, MTH1791 | Gram-positive bacteria Bacteria Bacteria | dTDP-D-glucose 4,6-dehydratase dTDP-4-dehydrorhamnose 3,5-epimerase dTDP-glucose pyrophosphorylase |
*The numbering of gene clusters is from the previously published analysis of gene neighborhoods in prokaryotic genomes [25].