title: Molecular Characterization of the N-Acetylglucosamine Catabolic Genes in Candida africana, a Natural N-Acetylglucosamine Kinase (HXK1) Mutant.
abstract: BACKGROUND
  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 biovariant of Candida albicans that is naturally unable to assimilate the GlcNAc.
  
  
  RESULTS
  DNA sequence analysis of these genes revealed a number of characteristic nucleotide substitutions 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 pathway. 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.
  
  
  CONCLUSIONS
  Our results show that C. africana is a natural HXK1 mutant, displaying a number of phenotypic characteristics distinct from typical C. albicans isolates.
authors.affiliation: Department of Biological and Environmental Sciences, University of Messina, Messina, Italy.
authors.forename: Maria Rosa
authors.initials: MR
authors.lastname: Felice
authors.affiliation: Department of Molecular and Cell Biology, University of California Merced, Merced, California, United States of America.
authors.forename: Megha
authors.initials: M
authors.lastname: Gulati
authors.affiliation: Department of Biological and Environmental Sciences, University of Messina, Messina, Italy.
authors.forename: Letterio
authors.initials: L
authors.lastname: Giuffrè
authors.affiliation: Department of Biological and Environmental Sciences, University of Messina, Messina, Italy.
authors.forename: Domenico
authors.initials: D
authors.lastname: Giosa
authors.affiliation: Department of Biological and Environmental Sciences, University of Messina, Messina, Italy.
authors.forename: Luca Marco
authors.initials: LM
authors.lastname: Di Bella
authors.affiliation: Department of Biological and Environmental Sciences, University of Messina, Messina, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Criseo
authors.affiliation: Department of Molecular and Cell Biology, University of California Merced, Merced, California, United States of America.
authors.forename: Clarissa J
authors.initials: CJ
authors.lastname: Nobile
authors.affiliation: Department of Biological and Environmental Sciences, University of Messina, Messina, Italy.|Scientific Institute for Research, Hospitalization and Health Care (IRCCS)-Centro Neurolesi "Bonino-Pulejo", Messina, Italy.
authors.forename: Orazio
authors.initials: O
authors.lastname: Romeo
authors.affiliation: Scientific Institute for Research, Hospitalization and Health Care (IRCCS)-Centro Neurolesi "Bonino-Pulejo", Messina, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Scordino
mesh_terms: D000117:Acetylglucosamine / Q000378:metabolism*; D002175:Candida / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D009154:Mutation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics* / Q000378:metabolism
chemical_list: D017853:Phosphotransferases (Alcohol Group Acceptor); C018716:N-acetylglucosamine kinase; D000117:Acetylglucosamine