Novel gene products associated with NdhD3/D4-containing NDH-1 complexes are involved in photosynthetic CO2 hydration in the cyanobacterium, Synechococcus sp. PCC7942

Shin Ichi Maeda, Murray R. Badger, G. Dean Price*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    164 Citations (Scopus)

    Abstract

    Cyanobacteria possess light-dependent CO2 uptake activity that results in the net hydration of CO2 to HCO3- and may involve a protein-mediated carbonic anhydrase (CA)-like activity. This process is vital for the survival of cyanobacteria and may be a contributing factor in the ecological success of this group of organisms. Here, via isolation of mutants of Synechococcus sp. PCC7942 that cannot grow under low-CO2 conditions, we have identified two novel genes, chpX and chpY, that are involved in light- dependent CO2 hydration and CO2 uptake reactions; co-inactivation of both these genes abolished both activities. The function and mechanism of the CO2 uptake systems supported by each chp gene product differs, with each associated with functionally distinct NAD(P)H dehydrogenase (NDH-1) complexes. The ChpX system has a low affinity for CO2 and is dependent on photosystem I cyclic electron transport, whereas the inducible ChpY system has a high affinity for CO2 and is dependent on linear electron transport. We believe that ChpX and ChpY are involved in a unique, net hydration of CO2 to HCO3-, that is coupled electron flow within the NDH-1 complex on the thylakoid membrane.

    Original languageEnglish
    Pages (from-to)425-435
    Number of pages11
    JournalMolecular Microbiology
    Volume43
    Issue number2
    DOIs
    Publication statusPublished - 2002

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