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KMID : 0545120040140061350
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Journal of Microbiology and Biotechnology
2004 Volume.14 No. 6 p.1350 ~ p.1355
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Overexpression of sprA and sprB Genes is Tightly Regulated in Streptomyces griseus
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Kim YH
Choi SS/Kang DK/Kang SS/Jeong BC/Hong SK
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Abstract
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The sprA and sprB genes encoding the chymotrypsin-like proteases Streptomyces griseus protease A (SGPA) and Streptomyces griseus protease B (SGPB) and the sprT gene that encodes Streptomyces griseus trypsin (SGT) were cloned from S. griseus and were overexpressed in various strains of S. griseus. When the sprT gene was introduced into S. griseus trypsin activity increased 2-fold in the A-factor deficient mutant strain S. griseus HH1 and increased 4-fold in the wild strain S. griseus IFO13350. However there was no detectable increase of chymotrypsin activity in the transformants of S. griseus with either sprA or sprB in contrast to the results obtained from S. lividans as a heterologous host. To solve the negative gene dosage effects in S. griseus either the sprA or the sprB genes with their own ribosome binding sites were linked to the downstream of the entire sprT gene and the coexpression efficiency was examined in S. lividans and S. griseus. The transformants of S. lividans with either pWHM3-TA (sprT+sprA) or pWHM3- TB (sprT+sprB) showed 3-fold increase of trypsin activity over that of the control however only the transformant of pWHM3-TB demonstrated 7-fold increase in chymotrypsin activity indicating that the pWHM3-TB has a successful construction for the overexpression of chymotrypsin in Streptomyces. When the coexpression vectors were introduced into S. griseus IFO 13350 the trypsin level sharply increased by more than 4-fold however the chymotrypsin level did not increase. These results strongly suggest that the overexpression of the sprA and sprB genes is tightly regulated in S. griseus.
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KEYWORD
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