Mutational deglycosylation of the Fc portion of immunoglobulin G causes O-sulfation of tyrosine adjacently preceding the originally glycosylated site.
Mutagenesis directed to a specific glycosylation site has been widely used to examine biological roles of individual glycans. However, occurrence of any post-translational modification on such deglycosylated mutants has not yet been well characterized. Here we performed mass spectrometric analyses of the Fc fragment of an unglycosylated mutant of mouse immunoglobulin G2b, whose conserved N-glycosylation site, i.e. Asn297, was substituted with alanine. We found that a major part of this mutant is sulfated at Tyr296, which adjacently precedes the originally glycosylated site. Our findings demonstrate that mutational deglycosylation can induce an unexpected post-translational modification in the protein.
Masuda
Katsuyoshi
K
Suntory Institute for Bioorganic Research, Wakayamadai, Shimamoto-cho, Mishima-gun, Osaka 618-8503, Japan.
Yamaguchi
Yoshiki
Y
Takahashi
Noriko
N
Jefferis
Royston
R
Kato
Koichi
K
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D006031:Glycosylation; D007141:Immunoglobulin Fc Fragments / Q000737:chemistry / Q000378:metabolism*; D007074:Immunoglobulin G / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D009154:Mutation / Q000235:genetics*; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D010449:Peptide Mapping; D021241:Spectrometry, Mass, Electrospray Ionization; D016339:Spectrometry, Mass, Fast Atom Bombardment; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism
D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D050505:Mutant Proteins; D010446:Peptide Fragments; C005662:tyrosine O-sulfate; D014443:Tyrosine