Recombinant plant gamma carbonic anhydrase homotrimers bind inorganic carbon

Gamma carbonic anhydrases (γCA) are widespread in Prokaryotes. In Eukaryotes, homologous genes were found only in plant genomes. In Arabidopsis and maize, the corresponding gene products are subunits of mitochondrial Complex I.At present, only γCA homotrimers of Methanosarcina thermophila (CAM) show reversible carbon dioxide (CO2) hydration activity. In the present work, it is shown that recombinant plant γCA2 could form homotrimers and bind H14CO3-. However, they are unable to catalyse the reversible hydration of CO2.These results suggest that plant γCAs do not act as carbonic anhydrases but with a related activity possibly contributing to recycle CO2 in the context of photorespiration.Structured summaryMINT-7266044: gamma CA2 (uniprotkb:Q9C6B3) and gamma CA2 (uniprotkb:Q9C6B3) physically interact (MI:0914) by dynamic light scattering (MI:0038)MINT-7266036: gamma CA2 (uniprotkb:Q9C6B3) and gamma CA2 (uniprotkb:Q9C6B3) physically interact (MI:0914) by molecular sieving (MI:0071)