Plant Purine Nucleoside Catabolism Employs a Guanosine Deaminase Required for the Generation of Xanthosine in <i>Arabidopsis</i>

Dahncke, Kathleen; Witte, Claus-Peter

doi:10.1105/tpc.113.117184

Cited by 47 publications

(55 citation statements)

References 47 publications

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“…6, A and B; Dahncke and Witte, 2013), as was shown previously for nonseed tissues (Jung et al, 2009;Riegler et al, 2011). The uridine concentration is about half in the double mutant in comparison with the nsh1 mutant (Fig.…”

Section: The Origin Of Cytosine In the Cda Mutantsupporting

confidence: 82%

“…Either DNA degradation was very limited or an alternative deaminase, such as AtCDAL4, might have compensated for the loss of AtCDA with respect to deoxycytidine deamination in the mutant lines. We favor the first explanation because (1) AtCDAL4 has a very low catalytic efficiency (Table II) and (2) an accumulation of deoxyguanosine was not observed in guanosine deaminase knockout lines despite strong accumulation of guanosine (Dahncke and Witte, 2013), indicating that no significant DNA degradation occurs.…”

Section: Deamination Of Cytidine In Vivomentioning

confidence: 90%

“…Cytosine, cytidine, CMP, uridine, and UMP (50, 100, 250, 500, 1,000, and 2,000 mM solutions) were treated as the samples and used as standards. The HPLC analysis procedure followed was according to the description by Dahncke and Witte (2013).…”

Section: Mutant Characterizationmentioning

confidence: 99%

“…For subcellular localization, AtCDA-YFP, GmCDA1-YFP, GmCDA2-YFP, and b-UP-CFP were coexpressed and analyzed by confocal microscopy as described by Dahncke and Witte (2013).…”

Section: Protoplasting and Subcellular Localizationmentioning

confidence: 99%

“…1). By contrast, adenosine is deaminated as nucleoside monophosphate (AMP to IMP by AMP deaminase; Xu et al, 2005), whereas G, similar to C, is deaminated at the level of the nucleoside (guanosine to xanthosine by guanosine deaminase; Dahncke and Witte, 2013). Cytidine deamination is required to feed C bases into pyrimidine ring catabolism, which is initiated from uracil ( Fig.…”

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confidence: 99%

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Of the nine cytidine deaminase like genes in Arabidopsis thaliana eight are pseudogenes and only one is required to maintain pyrimidine homeostasis in vivo

2016

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CYTIDINE DEAMINASE (CDA) catalyzes the deamination of cytidine to uridine and ammonia in the catabolic route of C nucleotides. The Arabidopsis (Arabidopsis thaliana) CDA gene family comprises nine members, one of which (AtCDA) was shown previously in vitro to encode an active CDA. A possible role in C-to-U RNA editing or in antiviral defense has been discussed for other members. A comprehensive bioinformatic analysis of plant CDA sequences, combined with biochemical functionality tests, strongly suggests that all Arabidopsis CDA family members except AtCDA are pseudogenes and that most plants only require a single CDA gene. Soybean (Glycine max) possesses three CDA genes, but only two encode functional enzymes and just one has very high catalytic efficiency. AtCDA and soybean CDAs are located in the cytosol. The functionality of AtCDA in vivo was demonstrated with loss-of-function mutants accumulating high amounts of cytidine but also CMP, cytosine, and some uridine in seeds. Cytidine hydrolysis in cda mutants is likely caused by NUCLEOSIDE HYDROLASE1 (NSH1) because cytosine accumulation is strongly reduced in a cda nsh1 double mutant. Altered responses of the cda mutants to fluorocytidine and fluorouridine indicate that a dual specific nucleoside kinase is involved in cytidine as well as uridine salvage. CDA mutants display a reduction in rosette size and have fewer leaves compared with the wild type, which is probably not caused by defective pyrimidine catabolism but by the accumulation of pyrimidine catabolism intermediates reaching toxic concentrations.

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Section: The Origin Of Cytosine In the Cda Mutantsupporting

confidence: 82%

Section: Deamination Of Cytidine In Vivomentioning

confidence: 90%

Section: Mutant Characterizationmentioning

confidence: 99%

“…For subcellular localization, AtCDA-YFP, GmCDA1-YFP, GmCDA2-YFP, and b-UP-CFP were coexpressed and analyzed by confocal microscopy as described by Dahncke and Witte (2013).…”

Section: Protoplasting and Subcellular Localizationmentioning

confidence: 99%

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confidence: 99%

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