TABLE 1.
Described enzymes in Cryptococcus neoformans
| Enzyme | Function(s)a | EC no. | Reference(s) |
|---|---|---|---|
| Localized on capsule and/or cell wall | |||
| 1,3-β-Glucan synthase | Involved in β-glucan synthesis | 2.4.1.34 | 135 |
| Acid phosphatase | Involved in fungal cell adhesion to host tissues, localized in lysosomes, and related to virulence (Table 2) | 3.1.3.2 | 106, 136, 137 |
| Cas1 glycosyltransferase | Participates in O-acetylation | 2.4.1.X | 138 |
| Chitin deacetylase | Involved in chitin metabolism | 3.5.1.41 | 139 |
| Chitin synthase | Involved in chitin synthesis | 2.4.1.16 | 140 |
| Chitinase | Involved in chitin degradation | 3.2.1.14 | 141 |
| Creatinine deaminase | Involved in arginine and proline metabolism | 3.5.4.21 | 142 |
| Esterase lipase | Catalyzes hydrolysis of fatty acids | 3.1.1.3 | 136 |
| GDP-mannose pyrophosphorylase | Involved in GDP-mannose synthesis | 2.7.7.13 | 143 |
| Glucan 1,3-β-glucosidase | Involved in glucan synthesis | 3.2.1.58 | 16 |
| Glucan 1,4-α-glucosidase | Involved in glucan synthesis | 3.2.1.3 | 16 |
| Gmt1 GDP-mannose | Transport of GDP-mannose | 2.7.7.22 | 144 |
| Lactonohydrolase | Deficient strains show larger capsule size and facilitated immune evasion | 3.1.1.15 | 37 |
| N-Acetylgalactosaminoglycan deacetylase | Involved in polysaccharide metabolism | 3.1.1.58 | 145 |
| Phosphoaminase | Involved in amino acid synthesis | 136 | |
| Phosphomannomutase | Involved in GDP-mannose synthesis | 5.4.2.8 | 143 |
| Phosphomannose isomerase | Involved in GDP-mannose synthesis | 5.3.1.8 | 143 |
| Uph1 ATPase | Required for vesicle acidification | 146 | |
| Uxs1 decarboxylase | Converts UDP-glucuronic acid to UDP-xylose | 147 | |
| α-1,3-Glucanase | Involved in glucan synthesis | 3.2.1.59 | 16 |
| α-Amylase | Hydrolyzes alpha bonds of several polysaccharides and involved in cell wall building | 3.2.1.1 | 148 |
| α-Glucosidase | Breaks down disaccharides to glucose and starch and involved in cell wall building | 3.2.1.20 | 136 |
| α-Mannosidase | Involved in cell building through mannose metabolism | 3.2.1.24 | 136 |
| α-Mannosyltransferase | Involved in polysaccharide metabolism | 2.4.1.132 | 38, 149 |
| β-Endoglucanase | Involved in cell wall formation | 3.2.1.4 | 148 |
| β-Glucosidase | Involved in cell wall formation | 3.2.1.21 | 136 |
| β-Glucuronidase | Involved in cell wall formation, catalyzing breakdown of complex carbohydrates | 3.2.1.31 | 136 |
| Secreted/released | |||
| Acyltransferase | Involved in food acquisition | 3.1.1.3 | 92 |
| Alkaline phosphatase | Involved in regulation of signaling cascades and several protein structure and localized in endoplasmic reticulum | 3.1.3.1 | 150 |
| Aspartyl protease | Involved in food acquisition | 3.4.23.X | 111 |
| Cellulase | Involved in polysaccharide degradation | 3.2.1.4 | 151 |
| DNase | DNA degradation and related to virulence (Table 2) | 3.1.21.1 | 79 |
| Metalloprotease | Catalyzes mechanism that involves a metal and related to virulence (Table 2) | 3.4.24.77 | 113, 152 |
| Phospholipase B | Similar to phospholipase C function, degrades cell membrane components, supports fungal attachment to host cells, localized on cell wall, and related to virulence (Table 2) | 3.1.1.5 | 91, 92 |
| Phospholipase C | Degrades cell membrane components, supports fungal attachment to host cells, and related to virulence (Table 2) | 3.1.4.11 | 93 |
| Protease | Performs proteolysis interfering with host defense response | 3.4.21.53 | 107, 108 |
| S2P endopeptidase | Performs proteolysis | 3.4.24.85 | 153 |
| Serine peptidase | Performs proteolysis, coordinating several physiological functions | 3.4.21.X | 152 |
| Superoxide dismutase | Catalyzes dismutation of toxic superoxide, converting superoxide to hydrogen peroxide and oxygen and related to virulence (Table 2) | 1.15.1.1 | 83–85 |
| Localized intracellularly | |||
| 2-Methylcitrate synthase | Converts acyl groups into alkyl groups on transfer | 2.3.3.5 | 154 |
| 3-β-Hydroxysteroid 3-dehydrogenase | Oxidizes a substrate by reduction reaction that transfers 1 or more hydrides to electron acceptor | 1.1.1.270 | 155 |
| 6-Phosphogluconate dehydrogenase | Involved in production of ribulose | 1.1.1.44 | 156, 157 |
| Acetate kinase | Catalyzes formation of acetyl-CoA | 2.7.2.1 | 158 |
| Aconitase | Catalyzes isomerization of citrate to isocitrate and involved in response to nitrosative stress | 4.2.1.3 | 159 |
| Adenylyl cyclase Cac1 | Converts ATP to cAMP | 4.6.1.1 | 160 |
| Alternative oxidase | Part of electron transport chain in mitochondria | 1.10.3.11 | 161 |
| Aminopeptidase | Catalyzes cleavage of amino acids from amino terminus of protein | 3.4.11.21 | 137 |
| C-9-methyltransferase | Involved in glycosphingolipid pathway | 2.1.1.129 | 127 |
| Can2 carbonic anhydrase | Responds directly to intracellular carbon oxide | 4.2.1.1 | 162, 163 |
| Casein kinase 1 | Dephosphorylation of Hog1 under stress conditions | 2.7.11.1 | 164 |
| Catalase | Protects cells from oxidative damage by reactive oxygen species | 1.11.1.6 | 137, 150 |
| Cytochrome c peroxidase | Takes reduced equivalents from cytochrome c and reduces hydrogen peroxide to water | 1.11.1.5 | 165 |
| Deacetylase | Removes acetyl groups from lysine in proteins and is localized in cell wall | 3.5.1.108 | 166 |
| Dolichyl-diphosphooligosaccharide-protein glycotransferase | Participates in N-glycan biosynthesis | 2.4.99.18 | 167 |
| Ferrochelatase | Catalyzes final step in heme biosynthesis from highly photoreactive porphyrins | 4.99.1.1 | 168 |
| Flippase | Participates in phospholipid translocation between membrane sides and localized in cell wall | 3.6.3.1 | 169, 170 |
| Glucose-6-phosphate dehydrogenase | Is in pentose phosphate pathway, maintaining the level of coenzyme NADPH | 1.1.1.49 | 171 |
| Glucose-phosphate isomerase | Catalyzes conversion of glucose-6-phosphate into fructose 6-phosphate | 5.3.1.9 | 172 |
| Glucosylceramide synthase | Involved in glucosylceramide synthesis, localized in cell wall, and related to virulence (Table 2) | 2.4.1.80 | 127, 128 |
| Glucuronyltransferase | Involved in biosynthetic pathway of O-acetylated mannan | 2.4.1.17 | 28 |
| Glutathione peroxidase | Protects cells from oxidative damage | 1.11.1.9 | 173 |
| Glyoxal oxidase | Copper metalloenzyme that catalyzes oxidation of aldehydes to corresponding carboxylic acids coupled to reduction of dioxygen to H2O2 | 1.2.1.23 | 148 |
| Homoisocitrate dehydrogenase | Participates in lysine biosynthesis | 1.1.1.87 | 115 |
| Homoserine kinase | Participates in glycine, serine, and threonine metabolism | 2.7.1.39 | 174 |
| Homoserine O-acetyltransferase | Participates in methionine and sulfur metabolism | 2.3.1.31 | 175 |
| Hyaluronic synthase | Involved in production of glycosaminoglycan at cell surface | 2.4.1.212 | 176 |
| Imidazole glycerol-phosphate dehydratase | Participates in histidine biosynthesis | 4.2.1.19 | 177 |
| IMP dehydrogenase | Participates in GTP biosynthesis | 1.1.1.205 | 178 |
| Inositol phosphotransferase 1 | Involved in glycosphingolipid pathway | 2.7.1.X | 127 |
| Inositol-phosphorylceramide synthase | Involved in glycosphingolipid pathway | 2.7.1.X | 179 |
| Ire1 kinase | Involved in cellular response to unfolded proteins | 2.7.11.1 | 180 |
| Isocitrate lyase | Catalyzes cleavage of isocitrate to succinate and glyoxylate | 4.1.3.1 | 181 |
| Laccase | Polyphenol oxidase and copper-containing oxidase enzyme, localized in cell wall, and related to virulence (Table 2) | 1.10.3.2 | 45, 46, 50 |
| Malate dehydrogenase | Catalyzes oxidation of malate to oxaloacetate | 1.1.1.37 | 182 |
| Mannitol-1-phosphate 5-dehydrogenase | Participates in fructose and mannose metabolism | 1.1.1.17 | 183, 184 |
| Mannose-1-phosphate guanylyltransferase (GDP) | Participates in fructose and mannose metabolism | 2.7.7.22 | 144 |
| Mannosyl phosphorylinositol ceramide synthase | Involved in glycosphingolipid pathway | 2.4.X.X | 127 |
| Mannosyltransferase | Participates in O-mannosylation of proteins and involved in cell wall integrity and morphogenesis | 2.4.1.109 | 185 |
| Myristoyl-CoA: protein N-myristoyltransferase | Catalyzes transfer of myristate from CoA to proteins | 2.3.1.97 | 116 |
| Pde1 phosphodiesterase | Modulates cAMP | 3.1.4.1 | 186 |
| Phosphoglucomutase | Participates in interconversion of glucose 1-phosphate and glucose 6-phosphate | 5.4.2.2 | 172 |
| Protein farnesyltransferase | Participates in formation of farnesyl protein and diphosphate | 2.5.1.58 | 187 |
| Rho1 GTPase | Involved in MAPK cascade | 3.6.5.2 | 188 |
| RNase III | Binds and cleaves double-stranded RNA | 3.1.26.3 | 189 |
| Saccharopine dehydrogenase | Participates in lysine metabolism | 1.5.1.10 | 190 |
| Sphingolipid methyltransferase 1 | Participates in methylation of glucosylceramide | 2.1.1.1 | 191 |
| Sterol 14α-demethylase | Involved in sterol metabolism | 1.14.13.7 | 192 |
| Sterol 24-C-methyltransferase | Involved in sterol metabolism | 1.15.1.1 | 193 |
| Thiol peroxidase | Reduces peroxides and inhibits hydrogen peroxide response | 1.11.1.7 | 194 |
| Thioredoxin reductase | Catalyzes reduction of thioredoxin | 1.8.1.9 | 195 |
| Threonine synthase | Participates in glycine, serine, and threonine metabolism | 4.2.3.1 | 174 |
| Thymidylate synthase | Catalyzes conversion of dUMP to deoxythymidine monophosphate | 2.1.1.45 | 196 |
| Transaldolase | Involved in pentose phosphate pathway | 2.2.1.2 | 159 |
| Trehalose-6-phosphate phosphatase | Participates in starch and sucrose metabolism | 3.1.3.12 | 197 |
| Trehalose-6-phosphate synthase | Participates in starch and sucrose metabolism | 2.4.1.15 | 197 |
| UDP-galactopyranose mutase | Catalyzes conversion of UDP-d-galactopyranose in UDP-d-galacto-1,4-furanose | 5.4.99.9 | 198 |
| UDP-glucose dehydrogenase | Participates in conversion of UDP-glucose to UDP-glucuronate, and formation of glycosaminoglycans | 1.1.1.22 | 199 |
| UDP-glucuronate decarboxylase | Participates in nucleotide sugar metabolism | 4.1.1.35 | 147 |
| Urease | Catalyzes hydrolysis of urea into carbono dioxide and ammonia and related to virulence (Table 2) | 3.5.1.5 | 74 |
| Xylosylphosphotransferase | Participates in O-glycosylation biosynthesis and related to virulence (Table 2) | 2.7.8.32 | 28, 31, 200 |
| Δ8 desaturase | Involved in glycosphingolipid pathway | 1.14.19.4 | 127 |
a
cAMP, cyclic AMP; MAPK, mitogen-activated protein kinase.