Primary structure of Streptomyces griseus metalloendopeptidase II.
Streptomyces griseus metalloendopeptidase II (SGMPII) is a unique protease, since it shows anomalous susceptibility to the proteinaceous "serine protease inhibitors" produced by Streptomyces, such as Streptomyces subtilisin inhibitor (SSI) and its homologous proteins. In this study, we analyzed the amino acid sequence of SGMPII by analyzing various peptide fragments produced enzymatically. The sequence of SGMPII, which is composed of 334 amino acids, showed no extensive similarity to SSI-insensitive metalloproteases produced by other species of Streptomyces, except for the amino acid residues essential for catalysis and zinc binding. However, SGMPII is 35-41% similar to thermolysin and its related metalloproteases, which are not inhibited by SSI, and the residues presumed to be critical for catalysis and zinc-binding are well conserved in SGMPII. Glu137 in a "His-Glu-Xaa-His" motif of SGMPII was identified as the residue modified by CICH2 CO-DL-(N-OH)Leu-Ala-Gly-NH2, an active-site-directed irreversible inhibitor of thermolysin-like metalloproteases. Based on the sequence comparison of SGMPII and other bacterial metalloproteases, we discuss the structural basis for the differences in substrate specificity and stability between SGMPII and other thermolysin-like proteases. A possible SSI-binding locus of SGMPII is also proposed.
Institute for Biomolecular Science, Gakushuin University, Tokyo, Japan.
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Kojima
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Kumazaki
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Ishii
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Miura
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry; D004795:Enzyme Stability; D008666:Metalloendopeptidases / Q000737:chemistry*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015842:Serine Proteinase Inhibitors / Q000737:chemistry; D013305:Streptomyces griseus / Q000201:enzymology*; D013379:Substrate Specificity; D013820:Thermolysin
D001426:Bacterial Proteins; D010446:Peptide Fragments; D015842:Serine Proteinase Inhibitors; C018150:subtilisin inhibitor protein, Streptomyces; D008666:Metalloendopeptidases; D013820:Thermolysin