Molecular Characterization of the N-Acetylglucosamine Catabolic Genes in Candida africana, a Natural N-Acetylglucosamine Kinase (HXK1) Mutant.

RESEARCH ARTICLE Molecular Characterization of the N- Acetylglucosamine Catabolic Genes in Candida africana, a Natural N-Acetylglucosamine Kinase (HXK1) Mutant Maria Rosa Felice 1 , Megha Gulati 2 , Letterio Giuffre 1 , Domenico Giosa 1 , Luca Marco Di Bella 1 , Giuseppe Criseo 1 , Clarissa J. Nobile 2 , Orazio Romeo 1,3 *, Fabio Scordino 3 1 Department of Biological and Environmental Sciences, University of Messina, Messina, Italy, 2 Department of Molecular and Cell Biology, University of California Merced, Merced, California, United States of America, 3 Scientific Institute for Research, Hospitalization and Health Care (IRCCS)—Centro Neurolesi Bonino-Pulejo , Messina, Italy * oromeo@unime.it Abstract Background OPEN ACCESS Citation: Felice MR, Gulati M, Giuffre L, Giosa D, Di Bella LM, Criseo G, et al. (2016) Molecular Characterization of the N-Acetylglucosamine Catabolic Genes in Candida africana, a Natural N- Acetylglucosamine Kinase (HXK1) Mutant. PLoS ONE 11(1): e0147902. doi:10.1371/journal.pone.0147902 Editor: Valerio Pazienza, IRCCS Casa Sollievo della Sofferenza Hospital, ITALY Received: August 12, 2015 Accepted: January 11, 2016 Published: January 25, 2016 Copyright: © 2016 Felice et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. In this study we report the genetic characterization, including expression analysis, of the genes involved in the uptake (NGT1) and catabolism (HXK1/NAG5, DAC1/NAG2, NAG1) of the aminosugar N-acetylglucosamine (GlcNAc) in Candida africana, a pathogenic biovar- iant of Candida albicans that is naturally unable to assimilate the GlcNAc. Results DNA sequence analysis of these genes revealed a number of characteristic nucleotide sub- stitutions including a unique and distinctive guanine insertion that shifts the reading frame and generates a premature stop codon (TGA) 154 bp downstream of the ATG start codon of the HXK1 gene encoding the GlcNAc-kinase, a key enzyme of the GlcNAc catabolic path- way. However, all examined genes produced transcripts even though different levels of expression were observed among the Candida isolates examined. In particular, we found an HXK1-idependent relationship of the NGT1 gene and a considerable influence of the GlcNAc-kinase functionality on the transcription of the DAC1 and NAG1 genes. Additional phenotypic analysis revealed that C. africana isolates are hyperfilamentous in the first 24- 48h of growth on filament-inducing media and revert to the yeast morphological form after 72h of incubation on these media. Data Availability Statement: All relevant data are within the paper. Funding: The authors received no specific funding for this work. Competing Interests: The authors have declared that no competing interests exist. Conclusions Our results show that C. africana is a natural HXK1 mutant, displaying a number of pheno- typic characteristics distinct from typical C. albicans isolates. PLOS ONE | DOI:10.1371/journal.pone.0147902 January 25, 2016