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Structural characterization of CA1462, the Candida albicans thiamine pyrophosphokinase.

ABSTRACT: BACKGROUND: In search of new antifungal targets of potential interest for pharmaceutical companies, we initiated a comparative genomics study to identify the most promising protein-coding genes in fungal genomes. One criterion was the protein sequence conservation between reference pathogenic genomes. A second criterion was that the corresponding gene in Saccharomyces cerevisiae should be essential. Since thiamine pyrophosphate is an essential product involved in a variety of metabolic pathways, proteins responsible for its production satisfied these two criteria. RESULTS: We report the enzymatic characterization and the crystallographic structure of the Candida albicans Thiamine pyrophosphokinase. The protein was co-crystallized with thiamine or thiamine-PNP. CONCLUSION: The presence of an inorganic phosphate in the crystallographic structure opposite the known AMP binding site relative to the thiamine moiety suggests that a second AMP molecule could be accommodated in the C. albicans structure. Together with the crystallographic structures of the enzyme/substrate complexes this suggests the existence of a secondary, less specific, nucleotide binding site in the Candida albicans thiamine pyrophosphokinase which could transiently serve during the release or the binding of ATP. The structures also highlight a conserved Glutamine residue (Q138) which could interact with the ATP alpha-phosphate and act as gatekeeper. Finally, the TPK/Thiamine-PNP complex is consistent with a one step mechanism of pyrophosphorylation.

SUBMITTER: Santini S

PROVIDER: S-EPMC2515308 | biostudies-literature | 2008

REPOSITORIES: biostudies-literature

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Structural characterization of CA1462, the Candida albicans thiamine pyrophosphokinase.

Santini Sébastien S Monchois Vincent V Mouz Nicolas N Sigoillot Cécile C Rousselle Tristan T Claverie Jean-Michel JM Abergel Chantal C

BMC structural biology 20080724

<h4>Background</h4>In search of new antifungal targets of potential interest for pharmaceutical companies, we initiated a comparative genomics study to identify the most promising protein-coding genes in fungal genomes. One criterion was the protein sequence conservation between reference pathogenic genomes. A second criterion was that the corresponding gene in Saccharomyces cerevisiae should be essential. Since thiamine pyrophosphate is an essential product involved in a variety of metabolic pa ...[more]

PMID: 18652651

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Project description:There have been increased reports of the isolation of unusual genotypic groups of Candida albicans (groups C and D) based on a well-defined genotypic method; this method uses cellular DNA digested with the EcoRI enzyme and the restriction fragment length polymorphisms (RFLPs) generated by agarose gel electrophoresis. The aim of the present study was to use additional molecular tools to characterize these unusual strains and to compare them with authentic strains of C. dubliniensis, a recently delineated species, and type I C. stellatoidea. The RFLPs of PCR products generated from the intergenic transcribed spacer (ITS) region did not differentiate among C. albicans genotypes A, B, and C and type I C. stellatoidea. However, this method did differentiate the C. albicans genotype D strains, which were identical to C. dubliniensis. The RFLPs generated by HaeIII digestion of the PCR products of the V3 region of the 25S rRNA gene (rDNA) could differentiate the same groups as RFLP analysis of the PCR amplicon of the ITS region. C. albicans genotype B isolates have been shown to have a transposable intron in the 25S rDNA, whereas genotype A isolates do not; C. dubliniensis strains also have an intron that is larger than that in genotype B C. albicans strains but that is in the same location. PCR designed to span this region resulted in a single product for C. albicans genotype A (450 bp), B (840 bp), type 1 C. stellatoidea (840 bp), and C. dubliniensis (1,080 bp), whereas the C. albicans genotype C isolates had two major products (450 and 840 bp). All C. albicans genotype D isolates gave a PCR product identical to that given by C. dubliniensis. These results indicate that those strains previously designated C. albicans genotype D are in fact C. dubliniensis, that no differences were found between type 1 C. stellatoidea and C. albicans genotype B strains, and that the C. albicans genotype C strains appear to have the transposable intron incompletely inserted throughout the ribosomal repeats in their genomes. The results of the antifungal susceptibility testing of 105 of these strains showed that, for fluconazole, strains of C. dubliniensis were significantly more susceptible than strains of each of the C. albicans genotypes (genotypes A, B, and C). The flucytosine susceptibility results indicated that strains of C. albicans genotype A were significantly less susceptible than either C. albicans genotype B or C. albicans genotype C strains. These results indicate that there is a correlation between the Candida groups and antifungal susceptibility.

Dataset Information

Structural characterization of CA1462, the Candida albicans thiamine pyrophosphokinase.

Publications

Structural characterization of CA1462, the Candida albicans thiamine pyrophosphokinase.

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