Deficiency of D-erythroascorbic acid attenuates hyphal growth and virulence of Candida albicans.
In some lower eukaryotes, D-erythroascorbic acid, a five-carbon analog of L-ascorbic acid, is present instead of L-ascorbic acid. We have cloned ALO1, the gene encoding D-arabinono-1,4-lactone oxidase, which catalyzes the final step of D-erythroascorbic acid biosynthesis in Candida albicans. The ALO1 gene contained a continuous open reading frame of 1,671 bp that encodes a polypeptide consisting of 557 amino acids with a calculated molecular mass of 63,428 Da. To investigate the functional roles of D-erythroascorbic acid in C. albicans, we disrupted or overexpressed the ALO1 gene. In the alo1/alo1 null mutants, the activity of D-arabinono-1,4-lactone oxidase was completely lost and D-erythroascorbic acid could not be detected. When ALO1 on a multicopy plasmid was transformed in C. albicans, the enzyme activity and the intracellular D-erythroascorbic acid level were increased up to 3.4-fold and 4.0-fold, respectively. The alo1/alo1 null mutants of C. albicans showed increased sensitivity towards oxidative stress. Overexpression of ALO1 made the cells more resistant to the same stress. The alo1/alo1 mutants showed defective hyphal growth and attenuated virulence. Taken together, our results suggest that D-erythroascorbic acid functions as an important antioxidant and can be considered one of the virulence factors enhancing the pathogenicity of C. albicans.
Huh
W K
WK
Laboratory of Biophysics, School of Biological Sciences and Institute of Microbiology, Seoul National University, Seoul 151-742, Republic of Korea.
Kim
S T
ST
Kim
H
H
Jeong
G
G
Kang
S O
SO
D000595:Amino Acid Sequence; D000818:Animals; D001205:Ascorbic Acid / Q000096:biosynthesis*; D002176:Candida albicans / Q000254:growth & development* / Q000472:pathogenicity*; D002177:Candidiasis / Q000382:microbiology* / Q000503:physiopathology; D003001:Cloning, Molecular; D005260:Female; D017353:Gene Deletion; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D017422:Sequence Analysis, DNA; D013401:Sugar Alcohol Dehydrogenases / Q000235:genetics / Q000378:metabolism*; D014774:Virulence
C005056:isoascorbic acid; D013401:Sugar Alcohol Dehydrogenases; C090492:D-arabinonolactone oxidase; D001205:Ascorbic Acid