Abstract
Cyanobacteria possess multiple mechanisms for regulating the pathways of photosynthetic and respiratory electron transport. Electron transport may be regulated indirectly by controlling the transfer of excitation energy from the light-harvesting complexes, or it may be more directly regulated by controlling the stoichiometry, localization, and interactions of photosynthetic and respiratory electron transport complexes. Regulation of the extent of linear vs. cyclic electron transport is particularly important for controlling the redox balance of the cell. This review discusses what is known of the regulatory mechanisms and the timescales on which they occur, with particular regard to the structural reorganization needed and the constraints imposed by the limited mobility of membrane-integral proteins in the crowded thylakoid membrane. Switching mechanisms requiring substantial movement of integral thylakoid membrane proteins occur on slower timescales than those that require the movement only of cytoplasmic or extrinsic membrane proteins. This difference is probably due to the restricted diffusion of membrane-integral proteins. Multiple switching mechanisms may be needed to regulate electron transport on different timescales.
Highlights
Cyanobacteria possess multiple mechanisms for regulating the pathways of photosynthetic and respiratory electron transport
Like other photosynthetic membranes (Kirchhoff et al, 2008), cyanobacterial thylakoid membranes are densely packed with membrane-integral proteins (Folea et al, 2008)
Most of the membrane area is devoted to photosynthetic electron transport and occupied by photosynthetic complexes, with Photosystem II and Photosystem I reaction centers often in close proximity (Folea et al, 2008)
Summary
Cyanobacteria possess multiple mechanisms for regulating the pathways of photosynthetic and respiratory electron transport. Restricted protein mobility has implications for any processes involving protein redistribution, including the biogenesis, turnover, and repair of the photosynthetic reaction centers, and regulation of electron transport and light-harvesting (Mullineaux, 2008a). REGULATORY SWITCHES IN CYANOBACTERIAL PHOTOSYNTHESIS Light energy absorbed by the photosynthetic pigments in the thylakoid membranes can be used for the generation of reduced NADPH with electrons extracted from water by Photosystem II.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
