The efficiency of N-linked glycosylation of bovine DNase I depends on the Asn-Xaa-Ser/Thr sequence and the tissue of origin.
Bovine DNase I contains two potential N-linked glycosylation sites with the sequences Asn(18)-Ala-Thr and Asn(106)-Asp-Ser. A previous report established that pancreatic DNase I has only one sugar chain at Asn(18) [Liao, Salnikow, Moore and Stein (1973) J. Biol. Chem. 248, 1489-1495]. We found, however, that bovine DNase I expressed in COS-1 cells was glycosylated about 70% at Asn(106) in addition to being completely glycosylated at Asn(18). Glycosylation of Asn(106) increased to 97% when Asp(107) was mutated to Glu or when Ser(108) was mutated to Thr. Mutation of Asp(107) to Trp had no effect, whereas a substitution with Pro at this position abolished glycosylation of Asn(106). Analysis of the state of glycosylation of DNase I purified from a variety of bovine tissues revealed that DNase I from spleen, submaxillary gland, lung and adrenal had two sugar chains, whereas enzyme from pancreas and kidney had only one sugar chain. These findings demonstrate a major difference in the ability of various tissues to utilize N-linked glycosylation signals that contain suboptimal residues in the second and third positions.
Nishikawa
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A
Department of Biochemistry, Okayama University of Science, 1-1, Ridai-cho, Okayama 700-0005, Japan. nishikaw@dbc.ous.ac.jp
Mizuno
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S
D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002241:Carbohydrates / Q000737:chemistry; D002417:Cattle; D003850:Deoxyribonuclease I / Q000737:chemistry / Q000378:metabolism*; D006031:Glycosylation; D011233:Precipitin Tests
D002241:Carbohydrates; D003850:Deoxyribonuclease I