Literature summary for 2.3.1.45 extracted from

Baumann, A.M.; Bakkers, M.J.; Buettner, F.F.; Hartmann, M.; Grove, M.; Langereis, M.A.; de Groot, R.J.; Muehlenhoff, M.
9-O-Acetylation of sialic acids is catalysed by CASD1 via a covalent acetyl-enzyme intermediate (2015), Nature Commun., 6, 7673.

Cloned(Commentary)

Cloned (Comment)	Organism
recombinant expression of N-terminally V5-tagged and C-terminally Myc-tagged enzyme in the murine fibroblast cell line LM-TK-, the enzyme co-localizes with the Golgi marker alpha-mannosidase II, and cytosolic and luminal orientation of N- and C-terminus, respectively, recombinant expression of a soluble secreted form of CASD1, which encompasses the SGNH-like luminal domain and a C-terminal Myc-His6-tag, in Spodoptera frugiperda SF9 cells via baculovirus transfection	Homo sapiens

Cloned (Comment)

Organism

recombinant expression of N-terminally V5-tagged and C-terminally Myc-tagged enzyme in the murine fibroblast cell line LM-TK-, the enzyme co-localizes with the Golgi marker alpha-mannosidase II, and cytosolic and luminal orientation of N- and C-terminus, respectively, recombinant expression of a soluble secreted form of CASD1, which encompasses the SGNH-like luminal domain and a C-terminal Myc-His6-tag, in Spodoptera frugiperda SF9 cells via baculovirus transfection

Homo sapiens

Protein Variants

Protein Variants	Comment	Organism
additional information	CASD1 knockout abolishes Sia O-acetylation in HAP1 cells. Transfection with CASD1 cDNA, but not empty vector, results in successful complementation of the loss-of-function defect and restored 9-O-acetylation of Golgi-localized sialoglycotopes	Homo sapiens
S94A	site-directed mutagenesis, inactive mutant	Homo sapiens

Localization

Localization	Comment	Organism	GeneOntology No.	Textmining
Golgi membrane	the enzyme is a multimembrane spanning protein with 13 transmembrane segments, the SGNH-like domain of CASD1 faces the Golgi lumen. The enzyme shows cytosolic and luminal orientation of its N- and C-terminus, respectively	Homo sapiens	139	-

Natural Substrates/ Products (Substrates)

Natural Substrates	Organism	Comment (Nat. Sub.)	Natural Products	Comment (Nat. Pro.)	Rev.	Reac.
acetyl-CoA + CMP-N-acetylneuraminate	Homo sapiens	-	CoA + N-acetyl-9-O-acetylneuraminate + CMP	-	?
additional information	Homo sapiens	enzyme CASD1 mediates 9-O-acetylation of cellular sialoglycans and sialoglycoconjugates	?	-	?

Organism

Organism	UniProt	Comment	Textmining
Homo sapiens	Q96PB1	-	-

Posttranslational Modification

Posttranslational Modification	Comment	Organism
glycoprotein	the soluble recombinant enzyme CASD1 expressed in Sf9 cells is N-glycosylated at the catalytic residue S94, the recombinant enzyme is therefore inactive	Homo sapiens

Source Tissue

Source Tissue	Comment	Organism	Textmining
HAP-1 cell	-	Homo sapiens	-

Substrates and Products (Substrate)

Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.
acetyl-CoA + CMP-N-acetylneuraminate	-	Homo sapiens	CoA + N-acetyl-9-O-acetylneuraminate + CMP	-	?
acetyl-CoA + CMP-N-acetylneuraminate	the N-terminal luminal domain of CASD1 demonstrate sialate 9-O-acetyltransferase activity, transfer of acetyl groups from acetyl-coenzyme A to CMP-activated sialic acid and formation of a covalent acetyl-enzyme intermediate	Homo sapiens	CoA + N-acetyl-9-O-acetylneuraminate + CMP	-	?
acetyl-CoA + GD3 ganglioside	-	Homo sapiens	CoA + 9'-O-acetyl-GD3 ganglioside	-	?
additional information	enzyme CASD1 mediates 9-O-acetylation of cellular sialoglycans and sialoglycoconjugates	Homo sapiens	?	-	?
additional information	while the N-terminal luminal domain of CASD1 displays the characteristic fold of an esterase, it does not appear to function as such, no esterase activity with synthetic acetylesterase substrate 4-nitrophenyl acetate nor towards natural O-acetylated sialoglycoconjugates. In vitro SOAT activity of recombinant soluble enzyme sCASD1	Homo sapiens	?	-	?

Synonyms

Synonyms	Comment	Organism
CASD1	-	Homo sapiens
sialate O-acetyltransferase	-	Homo sapiens

Temperature Optimum [°C]

Temperature Optimum [°C]	Temperature Optimum Maximum [°C]	Comment	Organism
37	-	assay at	Homo sapiens

pH Optimum

pH Optimum Minimum	pH Optimum Maximum	Comment	Organism
6.5	-	assay at	Homo sapiens

Cofactor

Cofactor	Comment	Organism	Structure
acetyl-CoA	-	Homo sapiens

General Information

General Information	Comment	Organism
evolution	the N-terminal domain of CASD1 differs from the canonical GDSL/SGNH fold by lacking the conserved residues G and N, and is therefore grouped into pfam family PF13839, i.e. GDSL/SGNH-like acylesterase family found in Pmr5 and Cas1p. While the N-terminal luminal domain of CASD1 displays the characteristic fold of an esterase39, it does not appear to function as such, no esterase activity with synthetic acetylesterase substrate 4-nitrophenylacetate nor towards natural O-acetylated sialoglycoconjugates	Homo sapiens
additional information	homology modelling and topology of human enzyme CASD1 residues 83-290, using the crystal structure of an isoamyl acetate-hydrolysing esterase from Saccharomyces cerevisiae, PDB ID 3mil as template, and predicting a GDSL/SGNH-like alpha/beta-fold that forms the scaffold for a catalytic triad composed of S94, D270 and H273, with S94 as part of a conserved GDS sequence motif, overview. the catalyytic triad is formed by D270, H273, and S94	Homo sapiens
physiological function	CASD1 is a sialate O-acetyltransferase that catalyzes the transfer of acetyl groups from acetyl-coenzyme A to CMP-activated sialic acid and formation of a covalent acetyl-enzyme intermediate and serves as key enzyme in the biosynthesis of 9-O-acetylated sialoglycans	Homo sapiens