Characterization of carbonic anhydrase XIII in the erythrocytes of the Burmese python, Python molurus bivittatus

Carbonic anhydrase (CA) is one of the most abundant proteins found in vertebrate erythrocytes with the majority of species expressing a low activity CA I and high activity CA II. However, several phylogenetic gaps remain in our understanding of the expansion of cytoplasmic CA in vertebrate erythrocy...

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Bibliographic Details
Published in:Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology Vol. 187; pp. 71 - 77
Main Authors: Esbaugh, A.J., Secor, S.M., Grosell, M.
Format: Journal Article
Language:English
Published: England Elsevier Inc 01.09.2015
Subjects:
Amino Acid Sequence
Animals
Biological Transport
Boidae - blood
Boidae - genetics
Boidae - metabolism
Boidae - physiology
CA I
CA XIII
carbon dioxide
Carbon Dioxide - metabolism
carbonate dehydratase
Carbonic anhydrase isoforms
Carbonic Anhydrases - chemistry
Carbonic Anhydrases - genetics
Carbonic Anhydrases - metabolism
copper
Cytoplasm - enzymology
Eating
erythrocytes
Erythrocytes - cytology
Erythrocytes - enzymology
excretion
genome
Isoenzymes - chemistry
Isoenzymes - genetics
Isoenzymes - metabolism
mammals
messenger RNA
Molecular Sequence Data
Nerodia
Phylogeny
proteins
Python molurus
Red blood cells
reptiles
Sequence Analysis
Specific dynamic action
titration
Transcription, Genetic
CA I
Red blood cells
Carbonic anhydrase isoforms
CA XIII
Specific dynamic action
ISSN:1096-4959, 1879-1107
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Summary:Carbonic anhydrase (CA) is one of the most abundant proteins found in vertebrate erythrocytes with the majority of species expressing a low activity CA I and high activity CA II. However, several phylogenetic gaps remain in our understanding of the expansion of cytoplasmic CA in vertebrate erythrocytes. In particular, very little is known about isoforms from reptiles. The current study sought to characterize the erythrocyte isoforms from two squamate species, Python molurus and Nerodia rhombifer, which was combined with information from recent genome projects to address this important phylogenetic gap. Obtained sequences grouped closely with CA XIII in phylogenetic analyses. CA II mRNA transcripts were also found in erythrocytes, but found at less than half the levels of CA XIII. Structural analysis suggested similar biochemical activity as the respective mammalian isoforms, with CA XIII being a low activity isoform. Biochemical characterization verified that the majority of CA activity in the erythrocytes was due to a high activity CA II-like isoform; however, titration with copper supported the presence of two CA pools. The CA II-like pool accounted for 90 % of the total activity. To assess potential disparate roles of these isoforms a feeding stress was used to up-regulate CO2 excretion pathways. Significant up-regulation of CA II and the anion exchanger was observed; CA XIII was strongly down-regulated. While these results do not provide insight into the role of CA XIII in the erythrocytes, they do suggest that the presence of two isoforms is not simply a case of physiological redundancy.
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ISSN:1096-4959
1879-1107
DOI:10.1016/j.cbpb.2015.05.006