Zam Is a Redox-Regulated Member of the RNB-Family Required for Optimal Photosynthesis in Cyanobacteria
The <i>zam</i> gene mediating resistance to acetazolamide in cyanobacteria was discovered thirty years ago during a drug tolerance screen. We use phylogenetics to show that Zam proteins are distributed across cyanobacteria and that they form their own unique clade of the ribonuclease II/...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-05-01
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| Series: | Microorganisms |
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| Online Access: | https://www.mdpi.com/2076-2607/10/5/1055 |
| _version_ | 1797497672823734272 |
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| author | Patrick E. Thomas Colin Gates William Campodonico-Burnett Jeffrey C. Cameron |
| author_facet | Patrick E. Thomas Colin Gates William Campodonico-Burnett Jeffrey C. Cameron |
| author_sort | Patrick E. Thomas |
| collection | DOAJ |
| description | The <i>zam</i> gene mediating resistance to acetazolamide in cyanobacteria was discovered thirty years ago during a drug tolerance screen. We use phylogenetics to show that Zam proteins are distributed across cyanobacteria and that they form their own unique clade of the ribonuclease II/R (RNB) family. Despite being RNB family members, multiple sequence alignments reveal that Zam proteins lack conservation and exhibit extreme degeneracy in the canonical active site—raising questions about their cellular function(s). Several known phenotypes arise from the deletion of <i>zam</i>, including drug resistance, slower growth, and altered pigmentation. Using room-temperature and low-temperature fluorescence and absorption spectroscopy, we show that deletion of <i>zam</i> results in decreased phycocyanin synthesis rates, altered PSI:PSII ratios, and an increase in coupling between the phycobilisome and PSII. Conserved cysteines within Zam are identified and assayed for function using in vitro and in vivo methods. We show that these cysteines are essential for Zam function, with mutation of either residue to serine causing phenotypes identical to the deletion of Zam. Redox regulation of Zam activity based on the reversible oxidation-reduction of a disulfide bond involving these cysteine residues could provide a mechanism to integrate the ‘central dogma’ with photosynthesis in cyanobacteria. |
| first_indexed | 2024-03-10T03:22:35Z |
| format | Article |
| id | doaj.art-ec47ed7197e84172878295f4b2c840b6 |
| institution | Directory Open Access Journal |
| issn | 2076-2607 |
| language | English |
| last_indexed | 2024-03-10T03:22:35Z |
| publishDate | 2022-05-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Microorganisms |
| spelling | doaj.art-ec47ed7197e84172878295f4b2c840b62023-11-23T12:17:10ZengMDPI AGMicroorganisms2076-26072022-05-01105105510.3390/microorganisms10051055Zam Is a Redox-Regulated Member of the RNB-Family Required for Optimal Photosynthesis in CyanobacteriaPatrick E. Thomas0Colin Gates1William Campodonico-Burnett2Jeffrey C. Cameron3Department of Biochemistry, University of Colorado, Boulder, CO 80309, USARenewable and Sustainable Energy Institute, University of Colorado, Boulder, CO 80309, USADepartment of Biochemistry, University of Colorado, Boulder, CO 80309, USADepartment of Biochemistry, University of Colorado, Boulder, CO 80309, USAThe <i>zam</i> gene mediating resistance to acetazolamide in cyanobacteria was discovered thirty years ago during a drug tolerance screen. We use phylogenetics to show that Zam proteins are distributed across cyanobacteria and that they form their own unique clade of the ribonuclease II/R (RNB) family. Despite being RNB family members, multiple sequence alignments reveal that Zam proteins lack conservation and exhibit extreme degeneracy in the canonical active site—raising questions about their cellular function(s). Several known phenotypes arise from the deletion of <i>zam</i>, including drug resistance, slower growth, and altered pigmentation. Using room-temperature and low-temperature fluorescence and absorption spectroscopy, we show that deletion of <i>zam</i> results in decreased phycocyanin synthesis rates, altered PSI:PSII ratios, and an increase in coupling between the phycobilisome and PSII. Conserved cysteines within Zam are identified and assayed for function using in vitro and in vivo methods. We show that these cysteines are essential for Zam function, with mutation of either residue to serine causing phenotypes identical to the deletion of Zam. Redox regulation of Zam activity based on the reversible oxidation-reduction of a disulfide bond involving these cysteine residues could provide a mechanism to integrate the ‘central dogma’ with photosynthesis in cyanobacteria.https://www.mdpi.com/2076-2607/10/5/1055reduction-oxidationphotosynthesiscyanobacteriaphotosystem IIphycobilisomeRNase |
| spellingShingle | Patrick E. Thomas Colin Gates William Campodonico-Burnett Jeffrey C. Cameron Zam Is a Redox-Regulated Member of the RNB-Family Required for Optimal Photosynthesis in Cyanobacteria Microorganisms reduction-oxidation photosynthesis cyanobacteria photosystem II phycobilisome RNase |
| title | Zam Is a Redox-Regulated Member of the RNB-Family Required for Optimal Photosynthesis in Cyanobacteria |
| title_full | Zam Is a Redox-Regulated Member of the RNB-Family Required for Optimal Photosynthesis in Cyanobacteria |
| title_fullStr | Zam Is a Redox-Regulated Member of the RNB-Family Required for Optimal Photosynthesis in Cyanobacteria |
| title_full_unstemmed | Zam Is a Redox-Regulated Member of the RNB-Family Required for Optimal Photosynthesis in Cyanobacteria |
| title_short | Zam Is a Redox-Regulated Member of the RNB-Family Required for Optimal Photosynthesis in Cyanobacteria |
| title_sort | zam is a redox regulated member of the rnb family required for optimal photosynthesis in cyanobacteria |
| topic | reduction-oxidation photosynthesis cyanobacteria photosystem II phycobilisome RNase |
| url | https://www.mdpi.com/2076-2607/10/5/1055 |
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