Table 2.
Characterization of identified metagenomic ORFs conferring QQ activities.
| Original clone designation | Characterization of identified potential QQ-ORF | Plasmid designa-tion | QQ activity of purified MalE-fusion protein |
|---|---|---|---|
| Black Sea III 6/G5 |
QQ-11: 309 aa | pRS620 | n. d. |
| - Closest homolog: | |||
| . AC: WP_041974651 (56 % aa identity) | |||
| . radical SAM protein from Geobacter sp. OR-1 (308 aa) | |||
| QQ-12: 478 aa | pRS621 | AHL + AI-2 | |
| - Closest homolog: | |||
| . AC: WP_034270149 (54 % aa identity) | |||
| . aminotransferase from Actinospica robinae (460 aa) | |||
| Salt Marsh, Hamburger Hallig, Germany IV 5/G8 |
QQ-2: 257 aa | pRS611 | AHL + AI-2 |
| - Closest homolog: | |||
| . AC: WP_044050964 (99 % aa identity) | |||
| . 3-hydroxy-2-methylbutyryl-CoA dehydrogenase from Planktomarina temperata (255 aa) | |||
| IV 5/G7 | QQ-3: 177 aa | pRS612 | AI-2 |
| - Closest homolog: | |||
| . AC: ADD95869 (32 % aa identity) | |||
| . hypothetical protein from uncultured organism (336 aa) | |||
| IV 5/E10 | QQ-4: 444 aa | pRS613 | AHL + AI-2 |
| - Closest homolog: | |||
| . AC: WP_052225045 (42 % aa identity) | |||
| . hypothetical protein from Mesorhizobium sp. F7 (518 aa) belonging to Ferredoxin reductase superfamily | |||
| IV 13/B4 | QQ-5: 373 aa | pRS614 | AHL + AI-2 |
| - Closest homolog: | |||
| . AC: WP_048599102 (99 % aa identity) | |||
| . 4-hydroxy-3-methylbut-2-en-1-yl diphosphate synthase from Nereida ignava (373 aa) | |||
| QQ-6: 373 aa | pRS615 | AHL + AI-2 | |
| - Equal to QQ-5 but with 4 random point mutations | |||
| QQ-7: 217 aa | pRS616 | AHL + AI-2 | |
| - Closest homolog: | |||
| . AC: WP_048599137 (100 % aa identity) | |||
| . 3-beta hydroxysteroid dehydrogenase from N. ignava (273 aa) | |||
| QQ-8: 376 aa | pRS617 | AHL | |
| - Closest homolog: | |||
| . AC: WP_048599109 (99 % aa identity) | |||
| . DNA-binding protein from N. ignava (801 aa) containing Lon protease domain | |||
| QQ-9: 424 aa | pRS618 | AHL + AI-2 | |
| - Closest homolog: | |||
| . AC: WP_048599099 (100 % aa identity) | |||
| . hypothetical protein from N. ignava (424 aa) belonging to N-acetylmuramoyl-L-alanine amidase superfamily | |||
| QQ-10: 406 aa | pRS619 | n. d. | |
| - Closest homolog: | |||
| . AC: WP_048599133 (100 % aa identity) | |||
| . 1-aminocyclopropane-1-carboxylate deaminase from N. ignava (392 aa) |
After expression and purification as MBP-fusion proteins selected QQ-ORFs were analyzed using reporter strains AI1-QQ.1 and AI2-QQ.2 (Weiland-Bräuer et al., 2015). AC, Accession number; aa, amino acids; n. d., not detected.