Involvement of the C-terminal tail of Arthrobacter ureafaciens sialidase isoenzyme M in cleavage of the internal sialic acid of ganglioside GM1.
Arthrobacter ureafaciens sialidase comprises four isoenzymes, L, M1, M2 and S, of which L, M1, and M2, but not S, have the unique ability to cleave GM1 ganglioside, but the hydrolysis of GM3 and colominic acid by S occurs at a higher rate than that by L, M1 and M2. Since the N-terminal amino acid sequences of L, M1, M2 and S were shown to be identical on protein sequencing, they were suggested to have arisen from the same protein through truncation at different C-terminal sites. A DNA segment containing an open reading frame was cloned from a genomic library, and the structural gene was found to comprise 2,970 bp encoding a protein of 990 amino acids including a signal peptide at the N-terminus, a conserved FYRIP-region and four Asp boxes. The molecular weights of the isoenzymes determined by MALDI-TOFMS revealed that L, M1, M2 and S should comprise amino acids 39-773, 39-653, 39-655 and 39-528, respectively. In fact, recombinant enzymes M2 and S prepared in Escherichia coli exhibited identical substrate specificities toward gangliosides as those of the purified enzymes. Consequently, the C-terminal tail of isoenzyme M2 might be involved in the hydrolysis of the internal sialic acid of GM1.
Iwamori
Masao
M
Department of Biochemistry, Faculty of Science and Technology, Kinki University, 3-4-1 Kowakae, Higashiosaka, Osaka 577-8502, Japan. iwamori@life.kindai.ac.jp
Kaido
Takeo
T
Iwamori
Yuriko
Y
Ohta
Yasuhiro
Y
Tsukamoto
Kentaro
K
Kozaki
Shunji
S
D000595:Amino Acid Sequence; D001173:Arthrobacter / Q000201:enzymology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D005677:G(M1) Ganglioside / Q000737:chemistry / Q000378:metabolism; D005798:Genes, Bacterial; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D019158:N-Acetylneuraminic Acid / Q000378:metabolism*; D009439:Neuraminidase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment
D001426:Bacterial Proteins; D007527:Isoenzymes; D005677:G(M1) Ganglioside; D009439:Neuraminidase; D019158:N-Acetylneuraminic Acid