Gamma carbonic anhydrase like complex interact with plant mitochondrial complex I

Abstract

We report the identification by two hybrid screens of two novel similar proteins, called Arabidopsis thaliana gamma carbonic anhydrase like1 and 2 (AtgammaCAL1 and AtgammaCAL2), that interact specifically with putative Arabidopsis thaliana gamma Carbonic Anhydrase (AtgammaCA) proteins in plant mitochondria. The interaction region that was located in the N-terminal 150 amino acids of mature AtgammaCA and AtgammaCA like proteins represents a new interaction domain. In vitro experiments indicate that these proteins are imported into mitochondria and are associated with mitochondrial complex I as AtgammaCAs. All plant species analyzed contain both AtgammaCA and AtgammaCAL sequences indicating that these genes were conserved throughout plant evolution. Structural modeling of AtgammaCAL sequences show a deviation of functionally important active site residues with respect to gammaCAs but could form active interfaces in the interaction with AtgammaCAs. We postulate a CA complex tightly associated to plant mitochondrial complex.

Subcomplexes of Ancestral Respiratory Complex I Subunits Rapidly Turn Over in Vivo as Productive Assembly Intermediates in Arabidopsis*

“…Single-particle electron microscope imaging analysis of isolated CI from Arabidopsis and Polytomella identified a specific matrix-exposed domain formed by ␥-carbonic anhydrase (␥-CA) subunits that are attached to the membrane arm of mitochondrial CI by the integral membrane protein CA2 (5). In Arabidopsis, this protein domain contains at least three different ␥-CA proteins, CA1 (At1g19580), CA2 (At1g47260), and CA3 (At5g66510), having conserved active site regions, and two less well conserved ␥-CA-like proteins, CAL1 (At5g66510) and CAL2 (At3g48680), which contain alterations to the primary structure of typical ␥-CAs (6). Links between these subunits and photosynthetic function have been postulated (7), a role in photomorphogenesis in plants has been shown by gene knock-out studies (8), and overexpression leads to male sterility in plants (9), but a CA activity from these proteins has not been experimentally confirmed.…”

“…Conservation and Losses of 20.9, ␥-CA, and ␥-CAL Proteins among Eukaryotic Lineages-Although ␥-CAs were initially considered plant-specific subunits of CI (6,10,11), more recent work has demonstrated the widespread occurrence of ␥-CA homologs throughout eukaryotes, with the notable exception of opisthokonts (animals ϩ fungi) (12). Extending this analysis, we have found that in organisms in which deep genome and/or transcriptome sequencing has been performed, multiple ␥-CA genes are often found (Table 1 and supplemental Data Set S4).…”

The Cytoplasmic Carbonic Anhydrases βCA2 and βCA4 Are Required for Optimal Plant Growth at Low CO2

“…The active unit of the bCA is a dimer where the active site is located at the interface of the two monomers (Kimber and Pai, 2000). In contrast, gCAs are trimers that have their active site zinc ion situated at the interface of two subunits coordinated by His residues from both subunits (Kisker et al, 1996;Iverson et al, 2000).In Arabidopsis (Arabidopsis thaliana), there are three gCA proteins and two g-like proteins that interact to form an extra structure of complex I of the mitochondrial electron transport chain (Perales et al, 2004;Sunderhaus et al, 2006). Although not active in vitro, gCA has been shown to bind inorganic carbon (Martin et al, 2009), affect complex I levels, plant growth, and gas-exchange rates when deleted (Perales et al, 2004;Soto et al, 2015), and cause plant sterility when ectopically overexpressed ).…”

“…In Arabidopsis (Arabidopsis thaliana), there are three gCA proteins and two g-like proteins that interact to form an extra structure of complex I of the mitochondrial electron transport chain (Perales et al, 2004;Sunderhaus et al, 2006). Although not active in vitro, gCA has been shown to bind inorganic carbon (Martin et al, 2009), affect complex I levels, plant growth, and gas-exchange rates when deleted (Perales et al, 2004;Soto et al, 2015), and cause plant sterility when ectopically overexpressed ).…”

“…Although not active in vitro, gCA has been shown to bind inorganic carbon (Martin et al, 2009), affect complex I levels, plant growth, and gas-exchange rates when deleted (Perales et al, 2004;Soto et al, 2015), and cause plant sterility when ectopically overexpressed ). Arabidopsis has eight aCA genes, but only aCA1, aCA2, and aCA3 appear to be expressed in leaf tissue.…”