Martin Victoria, Villarreal Fernando, Miras Isabelle, Navaza Alda, Haouz Ahmed, González-Lebrero Rodolfo M, Kaufman Sergio B, Zabaleta Eduardo
Instituto de Investigaciones Biológicas (IIB-CONICET-UNMdP), CC 1245, 7600 Mar del Plata, Argentina.
FEBS Lett. 2009 Nov 3;583(21):3425-30. doi: 10.1016/j.febslet.2009.09.055. Epub 2009 Oct 4.
Gamma carbonic anhydrases (gammaCA) 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 gammaCA homotrimers of Methanosarcina thermophila (CAM) show reversible carbon dioxide (CO(2)) hydration activity. In the present work, it is shown that recombinant plant gammaCA2 could form homotrimers and bind H(14)CO(3)(-). However, they are unable to catalyse the reversible hydration of CO(2). These results suggest that plant gammaCAs do not act as carbonic anhydrases but with a related activity possibly contributing to recycle CO(2) in the context of photorespiration.
γ-碳酸酐酶（γCA）广泛存在于原核生物中。在真核生物中，仅在植物基因组中发现了同源基因。在拟南芥和玉米中，相应的基因产物是线粒体复合体I的亚基。目前，只有嗜热甲烷八叠球菌（CAM）的γCA同三聚体表现出可逆的二氧化碳（CO₂）水合活性。在本研究中，结果表明重组植物γCA2能够形成同三聚体并结合H¹⁴CO₃⁻。然而，它们无法催化CO₂的可逆水合反应。这些结果表明，植物γCA并不作为碳酸酐酶起作用，而是具有一种相关活性，可能在光呼吸过程中有助于CO₂的循环利用。
