The Signal Transduction Protein PII Controls the Levels of the Cyanobacterial Protein PipX
Cyanobacteria, microorganisms performing oxygenic photosynthesis, must adapt their metabolic processes to environmental challenges such as day and night changes. PipX, a unique regulatory protein from cyanobacteria, provides a mechanistic link between the signalling protein PII, a widely conserved (...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2023-09-01
|
| Series: | Microorganisms |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2076-2607/11/10/2379 |
| _version_ | 1797572821556133888 |
|---|---|
| author | Antonio Llop Lorena Tremiño Raquel Cantos Asunción Contreras |
| author_facet | Antonio Llop Lorena Tremiño Raquel Cantos Asunción Contreras |
| author_sort | Antonio Llop |
| collection | DOAJ |
| description | Cyanobacteria, microorganisms performing oxygenic photosynthesis, must adapt their metabolic processes to environmental challenges such as day and night changes. PipX, a unique regulatory protein from cyanobacteria, provides a mechanistic link between the signalling protein PII, a widely conserved (in bacteria and plants) transducer of carbon/nitrogen/energy richness, and the transcriptional regulator NtcA, which controls a large regulon involved in nitrogen assimilation. PipX is also involved in translational regulation through interaction with the ribosome-assembly GTPase EngA. However, increases in the PipX/PII ratio are toxic, presumably due to the abnormally increased binding of PipX to other partner(s). Here, we present mutational and structural analyses of reported PipX-PII and PipX-NtcA complexes, leading to the identification of single amino acid changes that decrease or abolish PipX toxicity. Notably, 4 out of 11 mutations decreasing toxicity did not decrease PipX levels, suggesting that the targeted residues (F12, D23, L36, and R54) provide toxicity determinants. In addition, one of those four mutations (D23A) argued against the over-activation of NtcA as the cause of PipX toxicity. Most mutations at residues contacting PII decreased PipX levels, indicating that PipX stability would depend on its ability to bind to PII, a conclusion supported by the light-induced decrease of PipX levels in <i>Synechococcus elongatus</i> PCC7942 (hereafter <i>S. elongatus</i>). |
| first_indexed | 2024-03-10T21:02:20Z |
| format | Article |
| id | doaj.art-249d1bfc5be14a4da0e59c9c82bd0c6c |
| institution | Directory Open Access Journal |
| issn | 2076-2607 |
| language | English |
| last_indexed | 2024-03-10T21:02:20Z |
| publishDate | 2023-09-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Microorganisms |
| spelling | doaj.art-249d1bfc5be14a4da0e59c9c82bd0c6c2023-11-19T17:25:49ZengMDPI AGMicroorganisms2076-26072023-09-011110237910.3390/microorganisms11102379The Signal Transduction Protein PII Controls the Levels of the Cyanobacterial Protein PipXAntonio Llop0Lorena Tremiño1Raquel Cantos2Asunción Contreras3Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, 03690 San Vicente del Raspeig, SpainDepartamento de Fisiología, Genética y Microbiología, Universidad de Alicante, 03690 San Vicente del Raspeig, SpainDepartamento de Fisiología, Genética y Microbiología, Universidad de Alicante, 03690 San Vicente del Raspeig, SpainDepartamento de Fisiología, Genética y Microbiología, Universidad de Alicante, 03690 San Vicente del Raspeig, SpainCyanobacteria, microorganisms performing oxygenic photosynthesis, must adapt their metabolic processes to environmental challenges such as day and night changes. PipX, a unique regulatory protein from cyanobacteria, provides a mechanistic link between the signalling protein PII, a widely conserved (in bacteria and plants) transducer of carbon/nitrogen/energy richness, and the transcriptional regulator NtcA, which controls a large regulon involved in nitrogen assimilation. PipX is also involved in translational regulation through interaction with the ribosome-assembly GTPase EngA. However, increases in the PipX/PII ratio are toxic, presumably due to the abnormally increased binding of PipX to other partner(s). Here, we present mutational and structural analyses of reported PipX-PII and PipX-NtcA complexes, leading to the identification of single amino acid changes that decrease or abolish PipX toxicity. Notably, 4 out of 11 mutations decreasing toxicity did not decrease PipX levels, suggesting that the targeted residues (F12, D23, L36, and R54) provide toxicity determinants. In addition, one of those four mutations (D23A) argued against the over-activation of NtcA as the cause of PipX toxicity. Most mutations at residues contacting PII decreased PipX levels, indicating that PipX stability would depend on its ability to bind to PII, a conclusion supported by the light-induced decrease of PipX levels in <i>Synechococcus elongatus</i> PCC7942 (hereafter <i>S. elongatus</i>).https://www.mdpi.com/2076-2607/11/10/2379NtcA<i>Synechococcus elongatus</i>nitrogen regulation networklight and dark conditionsPipX toxicityprotein interaction |
| spellingShingle | Antonio Llop Lorena Tremiño Raquel Cantos Asunción Contreras The Signal Transduction Protein PII Controls the Levels of the Cyanobacterial Protein PipX Microorganisms NtcA <i>Synechococcus elongatus</i> nitrogen regulation network light and dark conditions PipX toxicity protein interaction |
| title | The Signal Transduction Protein PII Controls the Levels of the Cyanobacterial Protein PipX |
| title_full | The Signal Transduction Protein PII Controls the Levels of the Cyanobacterial Protein PipX |
| title_fullStr | The Signal Transduction Protein PII Controls the Levels of the Cyanobacterial Protein PipX |
| title_full_unstemmed | The Signal Transduction Protein PII Controls the Levels of the Cyanobacterial Protein PipX |
| title_short | The Signal Transduction Protein PII Controls the Levels of the Cyanobacterial Protein PipX |
| title_sort | signal transduction protein pii controls the levels of the cyanobacterial protein pipx |
| topic | NtcA <i>Synechococcus elongatus</i> nitrogen regulation network light and dark conditions PipX toxicity protein interaction |
| url | https://www.mdpi.com/2076-2607/11/10/2379 |
| work_keys_str_mv | AT antoniollop thesignaltransductionproteinpiicontrolsthelevelsofthecyanobacterialproteinpipx AT lorenatremino thesignaltransductionproteinpiicontrolsthelevelsofthecyanobacterialproteinpipx AT raquelcantos thesignaltransductionproteinpiicontrolsthelevelsofthecyanobacterialproteinpipx AT asuncioncontreras thesignaltransductionproteinpiicontrolsthelevelsofthecyanobacterialproteinpipx AT antoniollop signaltransductionproteinpiicontrolsthelevelsofthecyanobacterialproteinpipx AT lorenatremino signaltransductionproteinpiicontrolsthelevelsofthecyanobacterialproteinpipx AT raquelcantos signaltransductionproteinpiicontrolsthelevelsofthecyanobacterialproteinpipx AT asuncioncontreras signaltransductionproteinpiicontrolsthelevelsofthecyanobacterialproteinpipx |