In mammals various α-CA isoforms with different subcellular local

In mammals various α-CA isoforms with different subcellular localization and tissue distribution are implicated in many physiological processes such as carboxylation/decarboxylation reactions, transport of CO2 and/or HCO3-, pH regulation, ion exchange, calcification, Selumetinib metabolism of urea, glucose and lipids, tumorigenicity, bone resorption and many other physiological and pathological processes [5]. Members of β-CAs are predominant in

plants, algae, archaea and bacteria. In photosynthetic organisms β-CAs play an important role in transport and autotrophic fixation of CO2 while in prokaryotes β-CAs are involved in wide range of cellular functions including provision of HCO3 – for carboxylating enzymes which catalyze key steps in biosynthetic pathways for essential metabolites, such as amino acids, nucleotides, fatty acids [6, 7]. The γ-CAs are predominant in bacteria and archaea domains. In eukaryotes, they have so far been described only in photosynthetic organisms. While the physiological role of α-CAs in mammals and β-CAs in plants and prokaryotes, have been extensively studied, the role of γ-CAs remain elusive. To date, the only γ-CA that has been extensively characterized is “”Cam”" from the methanogenic Adriamycin molecular weight archaeon Methanosarcina thermophila [8, 9]. In the

cyanobacterium Synechocystis, the bifunctional CcmM protein localized in carboxysome (structure involved in CO2 concentration) shows an N-terminal γ-CA like domain which has been proposed to bind HCO3 Cyclin-dependent kinase 3 -/CO2 [10]. However, no carbonic anhydrase activity could be detected for the recombinant CcmM expressed in E. coli. Recently, a similar role for binding and transporting bicarbonate has been proposed for γ-CA subunits of plant mitochondrial complex, suggesting that the so-called γ-CAs in photosynthetic

eukaryotic organisms do not act as carbonic anhydrases but may have related activity contributing to CO2 recycling in photorespiration, or play a role in the carbon transport between mitochondria and chloroplasts to increase the efficiency of photosynthetic CO2 fixation [11]. Unraveling of microbial genome sequences has shown that γ-CAs are widespread in prokaryotes, and it is likely that these enzymes play selleck chemicals llc diverse roles in microorganisms. Investigations into the ways in which archaea and bacteria domains use γ-carbonic anhydrase may reveal novel aspects of prokaryotic physiology. We are analyzing the role of carbonic anhydrases in a nonphotosynthetic, Gram-negative, plant growth promoting α-proteobacterium, Azospirillum brasilense that lives in close association with the roots of several important crop plants and grasses and stimulates the growth of its host plant by producing phytohormones and siderophores [12]. Earlier, we have cloned the gene encoding β-CA from A. brasilense, overexpresed, purified and characterized β-CA. We also showed that the transcription of bca gene was down regulated by stationary phase, elevated CO2 and acidic pH [13].

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