Details zur Publikation |
| Kategorie | Textpublikation |
| Referenztyp | Zeitschriften |
| DOI | 10.1111/tpj.70974 |
Lizenz  |
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| Titel (primär) | Functional and structural insights into cyanobacterial CO2 concentrating mechanisms: from compartmentalization to regulation |
| Autor | Zimmer, E.; Poppitz, C.; Klähn, S.; Selim, K.A. |
| Quelle | Plant Journal |
| Erscheinungsjahr | 2026 |
| Department | SOMA |
| Band/Volume | 126 |
| Heft | 5 |
| Seite von | e70974 |
| Sprache | englisch |
| Topic | T7 Bioeconomy |
| Keywords | bacterial microcompartment; bicarbonate transporters; carbonic anhydrase; carboxysomes; CCM; CO2 metabolism; cyanobacteria; engineering CO2 fixation; photosynthesis and CO2 fixation; RuBisCO enzyme |
| Abstract |
Cyanobacteria are photoautotrophic microorganisms that fix CO2
through oxygenic photosynthesis during the day and rely on
heterotrophic metabolism at night. In nature, the availability of
inorganic carbon (Ci) is often limited, posing a major constraint on
photosynthetic efficiency. To overcome this, cyanobacteria have evolved a
sophisticated CO2-concentrating mechanism (CCM) that
enhances the catalytic performance of the primary carboxylating enzyme,
ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO). The CCM
functions by elevating intracellular CO2 concentrations around RubisCO to suppress its oxygenase activity and enhance CO2
fixation efficiency. Central to this system is the carboxysome, a
proteinaceous microcompartment that encapsulates RubisCO and carbonic
anhydrase, facilitating efficient conversion of bicarbonate (HCO3−) to CO2 and its subsequent fixation. This is complemented by multiple Ci transporters that mediate active uptake of CO2 and HCO3−. Five major transport systems have been characterized: two specialized NDH-1 complexes for CO2 transport and its conversion into HCO3−, and SbtA, BicA, and BCT1 for HCO3− uptake. Recent structural studies on CCM uptake systems have revealed key mechanisms of HCO3− transport, CO2
hydration and transport coupling. These insights provided a deeper
understanding of how these systems enhance Ci acquisition and maintain
photosynthetic efficiency across diverse environmental conditions and
various CO2 regimes. Moreover, the CCM is tightly regulated
at both transcriptional and post-translational levels to balance energy
usage and carbon demand. This review outlines our current insights into
the molecular architecture, transport dynamics, and regulatory networks
of the cyanobacterial CCM, emphasizing its critical role in
photosynthesis and its potential as a model for bioengineering enhanced
CO2 fixation or for engineering synthetic bacterial microcompartments. |
| Zimmer, E., Poppitz, C., Klähn, S., Selim, K.A. (2026): Functional and structural insights into cyanobacterial CO2 concentrating mechanisms: from compartmentalization to regulation Plant J. 126 (5), e70974 10.1111/tpj.70974 |
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