Laccase and Melanization in Clinically Important Cryptococcus Species Other than Cryptococcus neoformans

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Abstract
The laccase enzyme and melanin synthesis have been implicated as contributors to virulence in Cryptococcus neoformans . Since isolations of Cryptococcus species other than C. neoformans from clinical specimens have been increasing, we examined the laccase activities of C. albidus , C. laurentii , C. curvatus , and C. humicola . Incubation of cells with epinephrine produced adrenochrome color in C. albidus , C. laurentii , and C. curvatus but not in C. humicola . Activity was always less than in C. neoformans . Laccase was detected in the soluble fractions of disrupted C. albidus , C. laurentii , and C. curvatus cells. Activity staining of partially purified enzyme after nondenaturing polyacrylamide gel electrophoresis revealed that laccases from C. albidus , C. laurentii , and C. curvatus migrated more slowly than that from C. neoformans . One strain of C. curvatus exhibited two melanin bands. Thus, several clinically emerging Cryptococcus species express laccase and can synthesize melanin.

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