RibBX of Bradyrhizobium ORS285 Plays an Important Role in Intracellular Persistence in Various Aeschynomene Host Plants
Bradyrhizobium ORS285 forms a nitrogen-fixating symbiosis with both Nod factor (NF)-dependent and NF-independent Aeschynomene spp. The Bradyrhizobium ORS285 ribBA gene encodes for a putative bifunctional enzyme with 3,4-dihydroxybutanone phosphate (3,4-DHBP) synthase and guanosine triphosphate (GTP)...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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The American Phytopathological Society
2021-01-01
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| Series: | Molecular Plant-Microbe Interactions |
| Online Access: | https://doi.org/10.1094/MPMI-07-20-0209-R |
| _version_ | 1819135833491374080 |
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| author | Nico Nouwen Jean-Francois Arrighi Djamel Gully Eric Giraud |
| author_facet | Nico Nouwen Jean-Francois Arrighi Djamel Gully Eric Giraud |
| author_sort | Nico Nouwen |
| collection | DOAJ |
| description | Bradyrhizobium ORS285 forms a nitrogen-fixating symbiosis with both Nod factor (NF)-dependent and NF-independent Aeschynomene spp. The Bradyrhizobium ORS285 ribBA gene encodes for a putative bifunctional enzyme with 3,4-dihydroxybutanone phosphate (3,4-DHBP) synthase and guanosine triphosphate (GTP) cyclohydrolase II activities, catalyzing the initial steps in the riboflavin biosynthesis pathway. In this study, we show that inactivating the ribBA gene does not cause riboflavin auxotrophy under free-living conditions and that, as shown for RibBAs from other bacteria, the GTP cyclohydrolase II domain has no enzymatic activity. For this reason, we have renamed the annotated ribBA as ribBX. Because we were unable to identify other ribBA or ribA and ribB homologs in the genome of Bradyrhizobium ORS285, we hypothesize that the ORS285 strain can use unconventional enzymes or an alternative pathway for the initial steps of riboflavin biosynthesis. Inactivating ribBX has a drastic impact on the interaction of Bradyrhizobium ORS285 with many of the tested Aeschynomene spp. In these Aeschynomene spp., the ORS285 ribBX mutant is able to infect the plant host cells but the intracellular infection is not maintained and the nodules senesce early. This phenotype can be complemented by reintroduction of the 3,4-DHBP synthase domain alone. Our results indicate that, in Bradyrhizobium ORS285, the RibBX protein is not essential for riboflavin biosynthesis under free-living conditions and we hypothesize that its activity is needed to sustain riboflavin biosynthesis under certain symbiotic conditions. |
| first_indexed | 2024-12-22T10:25:22Z |
| format | Article |
| id | doaj.art-16857b6304c24030b54febff8b5ca6f8 |
| institution | Directory Open Access Journal |
| issn | 0894-0282 1943-7706 |
| language | English |
| last_indexed | 2024-12-22T10:25:22Z |
| publishDate | 2021-01-01 |
| publisher | The American Phytopathological Society |
| record_format | Article |
| series | Molecular Plant-Microbe Interactions |
| spelling | doaj.art-16857b6304c24030b54febff8b5ca6f82022-12-21T18:29:29ZengThe American Phytopathological SocietyMolecular Plant-Microbe Interactions0894-02821943-77062021-01-01341889910.1094/MPMI-07-20-0209-RRibBX of Bradyrhizobium ORS285 Plays an Important Role in Intracellular Persistence in Various Aeschynomene Host PlantsNico NouwenJean-Francois ArrighiDjamel GullyEric GiraudBradyrhizobium ORS285 forms a nitrogen-fixating symbiosis with both Nod factor (NF)-dependent and NF-independent Aeschynomene spp. The Bradyrhizobium ORS285 ribBA gene encodes for a putative bifunctional enzyme with 3,4-dihydroxybutanone phosphate (3,4-DHBP) synthase and guanosine triphosphate (GTP) cyclohydrolase II activities, catalyzing the initial steps in the riboflavin biosynthesis pathway. In this study, we show that inactivating the ribBA gene does not cause riboflavin auxotrophy under free-living conditions and that, as shown for RibBAs from other bacteria, the GTP cyclohydrolase II domain has no enzymatic activity. For this reason, we have renamed the annotated ribBA as ribBX. Because we were unable to identify other ribBA or ribA and ribB homologs in the genome of Bradyrhizobium ORS285, we hypothesize that the ORS285 strain can use unconventional enzymes or an alternative pathway for the initial steps of riboflavin biosynthesis. Inactivating ribBX has a drastic impact on the interaction of Bradyrhizobium ORS285 with many of the tested Aeschynomene spp. In these Aeschynomene spp., the ORS285 ribBX mutant is able to infect the plant host cells but the intracellular infection is not maintained and the nodules senesce early. This phenotype can be complemented by reintroduction of the 3,4-DHBP synthase domain alone. Our results indicate that, in Bradyrhizobium ORS285, the RibBX protein is not essential for riboflavin biosynthesis under free-living conditions and we hypothesize that its activity is needed to sustain riboflavin biosynthesis under certain symbiotic conditions.https://doi.org/10.1094/MPMI-07-20-0209-R |
| spellingShingle | Nico Nouwen Jean-Francois Arrighi Djamel Gully Eric Giraud RibBX of Bradyrhizobium ORS285 Plays an Important Role in Intracellular Persistence in Various Aeschynomene Host Plants Molecular Plant-Microbe Interactions |
| title | RibBX of Bradyrhizobium ORS285 Plays an Important Role in Intracellular Persistence in Various Aeschynomene Host Plants |
| title_full | RibBX of Bradyrhizobium ORS285 Plays an Important Role in Intracellular Persistence in Various Aeschynomene Host Plants |
| title_fullStr | RibBX of Bradyrhizobium ORS285 Plays an Important Role in Intracellular Persistence in Various Aeschynomene Host Plants |
| title_full_unstemmed | RibBX of Bradyrhizobium ORS285 Plays an Important Role in Intracellular Persistence in Various Aeschynomene Host Plants |
| title_short | RibBX of Bradyrhizobium ORS285 Plays an Important Role in Intracellular Persistence in Various Aeschynomene Host Plants |
| title_sort | ribbx of bradyrhizobium ors285 plays an important role in intracellular persistence in various aeschynomene host plants |
| url | https://doi.org/10.1094/MPMI-07-20-0209-R |
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