A Carbon Dioxide Limitation-Inducible Protein, ColA, Supports the Growth of Synechococcus sp. PCC 7002

Abstract

A limitation in carbon dioxide (CO 2 ), which occurs as a result of natural environmental variation, suppresses photosynthesis and has the potential to cause photo-oxidative damage to photosynthetic cells. Oxygenic phototrophs have strategies to alleviate photo-oxidative damage to allow life in present atmospheric CO 2 conditions. However, the mechanisms for CO 2 limitation acclimation are diverse among the various oxygenic phototrophs, and many mechanisms remain to be discovered. In this study, we found that the gene encoding a CO 2 limitation-inducible protein, ColA, is required for the cyanobacterium Synechococcus sp. PCC 7002 (S. 7002) to acclimate to limited CO 2 conditions. An S. 7002 mutant deficient in ColA (∆colA) showed lower chlorophyll content, based on the amount of nitrogen, than that in S. 7002 wild-type (WT) under ambient air but not high CO 2 conditions. Both thermoluminescence and protein carbonylation detected in the ambient air grown cells indicated that the lack of ColA promotes oxidative stress in S. 7002. Alterations in the photosynthetic O 2 evolution rate and relative electron transport rate in the short-term response, within an hour, to CO 2 limitation were the same between the WT and ∆colA. Conversely, these photosynthetic parameters were mostly lower in the long-term response of a few days in ∆colA than in the WT. These data suggest that ColA is required to sustain photosynthetic activity for living under ambient air in S. 7002. The unique phylogeny of ColA revealed diverse strategies to acclimate to CO 2 limitation among cyanobacteria.

Medium‐chain dehydrogenase/reductase and aldo‐keto reductase scavenge reactive carbonyls in Synechocystis sp. PCC 6803

“…For the detection of carbonylated proteins, crude soluble and membrane fractions (17 μg and 5 μg protein, respectively) were analyzed by SDS/PAGE. Following electrophoresis and electrotransfer to a PVDF membrane, the proteins were derivatized with 2,4‐dinitrophenylhydrazine, and were then detected with a polyclonal antibody specific to the 2,4‐dinitrophenyl groups (Cosmo Bio, Tokyo, Japan), as previously described .…”

Coral symbionts evolved a functional polycistronic flavodiiron gene

“…A CO2 limitation-inducible protein (ColA), a unique protein to some cyanobacteria, is also included in the FLV4-2 operon except for Synechococcus sp. PCC 7002 (S7002) having ColA alone (Shimakawa et al 2017b;Bersanini et al 2017). We searched for analogous genes to cyanobacterial FLV in the transcriptomic data of three strains of Symbiodiniaceae, Symbiodinium tridacnidorum, Cladocopium sp.…”