Processing of an intracellular immature pullulanase to the mature form involves enzymatic activation and stabilization in alkaliphilic Bacillus sp. S-1

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Title
Processing of an intracellular immature pullulanase to the mature form involves enzymatic activation and stabilization in alkaliphilic Bacillus sp. S-1
Author(s)
Moon Joo Lee; Bong Seok kang; Dong Soo Kim; Yong Tae Kim; Se Kwon Kim; Kang Hyun Chung; June Ki Kim; Kyung Soo Nam; Young Choon Lee; Cheorl Ho Kim
Bibliographic Citation
BMB Reports, vol. 30, no. 1, pp. 46-54
Publication Year
1997
Abstract
Alkaliphilic Bacillus sp. S-1 secretes a large amount (approximately 80% of total pullulanase activity) of an extracellular pullulanase (PUL-E). The pullulanase exists in two forms: a precursor form (PUL-I: M, 180,000), and a processed form (PUL-E: M, 140,000). Two forms were purified to homogeneity and their properties were compared. PUL-I was different in molecular weight, isoelectric point, NH2-terminal amino acid sequence, and stabilities over pH and temperature ranges. The catalytic activities of PUL-I were also distinguishable in the Km and Vmax values for various substrates, and in the specific activity for pullulan hydrolysis. PUL-E showed 10-fold higher specific activities than PUL-I. However. PUL-I is immunologically identical to PUL-E, suggesting that PUL-I is initially synthesized and proteolytically processed to the mature form of PUL-E. Processing was inhibited by PMSF. but not by pepstatin, suggesting that some intracellular serine proteases could be responsible for processing of the PUL-I. PUL-I has a different conformational structure for antibody recognition from that of PUL-E. It is also postulated that the translocation of alkaline pullulanase (AP) in the bacterium possibly requires processing of the NH2-terminal region of the AP protein. Processing of the precursor involves a conformational shift, resulting in a mature form. Therefore, precursor processing not only cleaves the signal peptide, but also induces conformational shift, allowing development of active form of the enzyme.
Keyword
activationalkaliphilic bacillus sp. S-1conformationprocessingpullulanase
ISSN
1225-8687
Publisher
South Korea
Type
Article
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1. Journal Articles > Journal Articles
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