An acetylation site in lectin domain modulates the biological activity of polypeptide GalNAc-transferase-2

TY - JOUR

T1 - An acetylation site in lectin domain modulates the biological activity of polypeptide GalNAc-transferase-2

AU - Zlocowski, Natacha

AU - Lorenz, Virginia

AU - Bennett, Eric Paul

AU - Clausen, Henrik

AU - Nores, Gustavo Alejandro

AU - Irazoqui, Fernando

PY - 2013/1

Y1 - 2013/1

N2 - Polypeptide GalNAc-transferases (ppGalNAc-Ts) are a family of enzymes that catalyze the initiation of mucintype O-glycosylation. All ppGalNAc-T family members contain a common (QXW) 3 motif, which is present in the R-type lectin group. The acetylation site K521 is part of the QKW motif of -trefoil in the lectin domain of ppGalNAc-T2. We used a combination of acetylation and site-directed mutagenesis approaches to examine the functional role of K521 in ppGalNAc-T2. Binding assays of non-acetylated and acetylated forms of the mutant ppGalNAc-T2 K521Q to various naked and α GalNAc-glycosylated mucin peptides indicated that the degree of interaction of lectin domain with α GalNAc depends on the peptide sequence of mucin. Studies of the inhibitory effect of various carbohydrates on the interactions of ppGalNAc-T2 with MUC1 α GalNAc indicate that point K521Q mutation enhance the carbohydrate specificity of lectin domain for α GalNAc. K521Q mutation resulted in an enzyme activity lower than that of the wildtype ppGalNAc-T2, similar to the acetylation of ppGalNAc-T2. We conclude that an acetylation site in the QKW motif of the lectin domain modulates carbohydrate recognition specificity and catalytic activity of ppGalNAc-T2 for partially preglycosylated acceptors and a certain naked peptide. Posttranslational modifications of ppGalNAc-Ts, such as acetylation, may play key roles in modulating the functions of the R-type lectin domains in cellular homeostasis.

AB - Polypeptide GalNAc-transferases (ppGalNAc-Ts) are a family of enzymes that catalyze the initiation of mucintype O-glycosylation. All ppGalNAc-T family members contain a common (QXW) 3 motif, which is present in the R-type lectin group. The acetylation site K521 is part of the QKW motif of -trefoil in the lectin domain of ppGalNAc-T2. We used a combination of acetylation and site-directed mutagenesis approaches to examine the functional role of K521 in ppGalNAc-T2. Binding assays of non-acetylated and acetylated forms of the mutant ppGalNAc-T2 K521Q to various naked and α GalNAc-glycosylated mucin peptides indicated that the degree of interaction of lectin domain with α GalNAc depends on the peptide sequence of mucin. Studies of the inhibitory effect of various carbohydrates on the interactions of ppGalNAc-T2 with MUC1 α GalNAc indicate that point K521Q mutation enhance the carbohydrate specificity of lectin domain for α GalNAc. K521Q mutation resulted in an enzyme activity lower than that of the wildtype ppGalNAc-T2, similar to the acetylation of ppGalNAc-T2. We conclude that an acetylation site in the QKW motif of the lectin domain modulates carbohydrate recognition specificity and catalytic activity of ppGalNAc-T2 for partially preglycosylated acceptors and a certain naked peptide. Posttranslational modifications of ppGalNAc-Ts, such as acetylation, may play key roles in modulating the functions of the R-type lectin domains in cellular homeostasis.

U2 - 10.1515/hsz-2012-0191

DO - 10.1515/hsz-2012-0191

M3 - Journal article

C2 - 23096348

SN - 1431-6730

VL - 394

SP - 69

EP - 77

JO - Biological Chemistry

JF - Biological Chemistry

IS - 1

ER -