Characterization of CA XIII, a Novel Member of the Carbonic Anhydrase Isozyme Family

University of Florence, Florens, Tuscany, Italy
Journal of Biological Chemistry (Impact Factor: 4.57). 02/2004; 279(4):2719-27. DOI: 10.1074/jbc.M308984200
Source: PubMed


The carbonic anhydrase (CA) gene family has been reported to consist of at least 11 enzymatically active members and a few
inactive homologous proteins. Recent analyses of human and mouse databases provided evidence that human and mouse genomes
contain genes for still another novel CA isozyme hereby named CA XIII. In the present study, we modeled the structure of human
CA XIII. This model revealed a globular molecule with high structural similarity to cytosolic isozymes, CA I, II, and III.
Recombinant mouse CA XIII showed catalytic activity similar to those of mitochondrial CA V and cytosolic CA I, with kcat/Km of 4.3 × 107 m–1 s–1, and kcat of 8.3 × 104 s–1. It is very susceptible to inhibition by sulfonamide and anionic inhibitors, with inhibition constants of 17 nm for acetazolamide, a clinically used sulfonamide, and of 0.25 μm, for cyanate, respectively. Using panels of cDNAs we evaluated human and mouse CA13 gene expression in a number of different tissues. In human tissues, positive signals were identified in the thymus, small
intestine, spleen, prostate, ovary, colon, and testis. In mouse, positive tissues included the spleen, lung, kidney, heart,
brain, skeletal muscle, and testis. We also investigated the cellular and subcellular localization of CA XIII in human and
mouse tissues using an antibody raised against a polypeptide of 14 amino acids common for both human and mouse orthologues.
Immunohistochemical staining showed a unique and widespread distribution pattern for CA XIII compared with the other cytosolic
CA isozymes. In conclusion, the predicted amino acid sequence, structural model, distribution, and activity data suggest that
CA XIII represents a novel enzyme, which may play important physiological roles in several organs.

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Available from: Bairong Shen, Mar 23, 2014
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    • "However, CA III deficiency in mice results only in a mild muscle defect [16], pointing at some compensatory events by other isoenzymes. CA XIII shows a widespread distribution in adult human and murine tissues [17]. "
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    ABSTRACT: Carbonic anhydrases (CAs) play fundamental roles in several physiological events, and emerging evidence points at their involvement in an array of disorders, including cancer. The expression of CAs in the different cells of teeth is unknown, let alone their expression patterns during odontogenesis. As a first step towards understanding the role of CAs during odontogenesis, we used immunohistochemistry, histochemistry and in situ hybridization to reveal hitherto unknown dynamic distribution patterns of eight CAs in mice. The most salient findings include expression of CAII/Car2 not only in maturation-stage ameloblasts (MA) but also in the papillary layer, dental papilla mesenchyme, odontoblasts and the epithelial rests of Malassez. We uncovered that the latter form lace-like networks around incisors; hitherto these have been known to occur only in molars. All CAs studied were produced by MA, however CAIV, CAIX and CARPXI proteins were distinctly enriched in the ruffled membrane of the ruffled MA but exhibited a homogeneous distribution in smooth-ended MA. While CAIV, CAVI/Car6, CAIX, CARPXI and CAXIV were produced by all odontoblasts, CAIII distribution displayed a striking asymmetry, in that it was virtually confined to odontoblasts in the root of molars and root analog of incisors. Remarkably, from initiation until near completion of odontogenesis and in several other tissues, CAXIII localized mainly in intracellular punctae/vesicles that we show to overlap with LAMP-1- and LAMP-2-positive vesicles, suggesting that CAXIII localizes within lysosomes. We showed that expression of CAs in developing teeth is not confined to cells involved in biomineralization, pointing at their participation in other biological events. Finally, we uncovered novel sites of CA expression, including the developing brain and eye, the olfactory epithelium, melanoblasts, tongue, notochord, nucleus pulposus and sebaceous glands. Our study provides important information for future single or multiple gene targeting strategies aiming at deciphering the function of CAs during odontogenesis.
    PLoS ONE 05/2014; 9(5):e96007. DOI:10.1371/journal.pone.0096007 · 3.23 Impact Factor
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    • "The mammalian α-CA gene family includes at least 15 enzymatically active isoforms with different structural and catalytic properties. Six of the active CA isozymes are cytosolic (CA-I, -II, -III, -VII, -VIII, and -XIII), 4 are membrane-associated (CA-IV, -IX, -XII, and -XIV), 2 are mitochondrial (CA-VA and CA-VB), and 1 is secretory form (CA-VI), while 2 CA-related proteins (CA-X and XI) are inactive variants [1-3]. The physiological function of carbonic anhydrase is to maintain the acid–base balance in various tissues and biological fluids [4]. "
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    ABSTRACT: Carbonic anhydrase VI (CA-VI) is produced by the salivary gland and is secreted into the saliva. Although CA-VI is found in the epithelial cells of distal straight tubule of swine kidneys, the exact function of CA-VI in the kidneys remains unclear. CA-VI was located in the epithelial cells of distal straight tubule of swine kidneys.A full-length cDNA clone of CA-VI was generated from the swine parotid gland by reverse transcription polymerase chain reaction, using degenerate primers designed based on conserved regions of the same locus in human and bovine tissues.The cDNA sequence was 1348 base pairs long and was predicted to encode a 317 amino acid polypeptide with a putative signal peptide of 17 amino acids. The deduced amino acid sequence of mature CA-VI was most similar (77.4%) to that of human CA-VI. CA-VI expression was confirmed in both normal and nephritic kidneys, as well as parotid. As the primers used in this study spanned two exons, the influence of genomic DNA was not detected. The expression of CA-VI was demonstrated in both normal and nephritic kidneys, and mRNA of CA-VI in the normal kidneys which was the normalised to an endogenous beta-actin was 0.098 +/- 0.047, while it was significantly lower in the diseased kidneys (0.012 +/- 0.007). The level of CA-VI mRNA in normal kidneys was 19-fold lower than that of the parotid gland (1.887). The localisation of CA-VI indicates that it may play a specialised role in the kidney.
    BMC Research Notes 02/2014; 7(1):116. DOI:10.1186/1756-0500-7-116
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    • "Human CA XIII isozyme has been characterized [11]. The enzyme expression in human tissues showed that CA XIII is found in several organs including the thymus, kidney, submandibular gland, small intestine, and most notably in reproductive organs suggesting involvement in the fertilization process [7,11]. The CO2 hydration activity showed CA XIII to be a catalyst of medium efficiency [12]. "
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    ABSTRACT: Background Human carbonic anhydrases (CAs) play crucial role in various physiological processes including carbon dioxide and hydrocarbon transport, acid homeostasis, biosynthetic reactions, and various pathological processes, especially tumor progression. Therefore, CAs are interesting targets for pharmaceutical research. The structure-activity relationships (SAR) of designed inhibitors require detailed thermodynamic and structural characterization of the binding reaction. Unfortunately, most publications list only the observed thermodynamic parameters that are significantly different from the intrinsic parameters. However, only intrinsic parameters could be used in the rational design and SAR of the novel compounds. Results Intrinsic binding parameters for several inhibitors, including ethoxzolamide, trifluoromethanesulfonamide, and acetazolamide, binding to recombinant human CA XIII isozyme were determined. The parameters were the intrinsic Gibbs free energy, enthalpy, entropy, and the heat capacity. They were determined by titration calorimetry and thermal shift assay in a wide pH and temperature range to dissect all linked protonation reaction contributions. Conclusions Precise determination of the inhibitor binding thermodynamics enabled correct intrinsic affinity and enthalpy ranking of the compounds and provided the means for SAR analysis of other rationally designed CA inhibitors.
    BMC Biophysics 06/2012; 5(1):12. DOI:10.1186/2046-1682-5-12 · 2.89 Impact Factor
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