tailieunhanh - Báo cáo khoa học: In vitro and in vivo self-cleavage of Streptococcus pneumoniae signal peptidase I

We have previously demonstrated thatStreptococcus pneumoniae signal peptidase (SPase) I catalyzes a self-cleavage to result in a truncated product, SPase37–204 [Peng, ., Wang, L., Moomaw, J., Peery, ., Sun, ., Johnson, ., Lu, J., Treadway, P., Skatrud, . & Wang, . (2001)J. , 621–627]. In this study, we investigated the effect of phospholipid onin vitro self-cleavage ofS. | Eur. J. Biochem. 269 3969-3977 2002 FEBS 2002 doi In vitro and in vivo self-cleavage of Streptococcus pneumoniae signal peptidase I Feng Zheng Eddie L. Angleton Jin Lu and Sheng-Bin Peng Infectious Diseases Research Lilly Research Laboratories Indianapolis IN USA We have previously demonstrated that Streptococcus pneumoniae signal peptidase SPase I catalyzes a selfcleavage to result in a truncated product SPase37-204 Peng . Wang L. Moomaw J. Peery . Sun . Johnson . Lu J. Treadway P. Skatrud . Wang . 2001 J. Bacteriol. 183 621-627 . In this study we investigated the effect of phospholipid on in vitro self-cleavage of S. pneumoniae SPase I. In the presence of phospholipid the self-cleavage predominantly occurred at one cleavage site between Gly36-His37 whereas the selfcleavage occurred at multiple sites in the absence of phospholipid and two additional self-cleavage sites Ala65-His66 and Ala143-Phe144 were identified. All three self-cleavage sites strongly resemble the signal peptide cleavage site and follow the -1 -3 rule for SPase I recognition. Kinetic analysis demonstrated that self-cleav age is a concentration dependent and intermolecular event and the activity in the presence of phospholipid is 25-fold higher than that in the absence of phospholipid. Biochemical analysis demonstrated that SPase37-204 the major product of the self-cleavage totally lost activity to cleave its substrates indicating that the self-cleavage resulted in the inactivation of the enzyme. More importantly the self-cleavage was demonstrated to be happening in vivo in all the growth phases of S. pneumoniae cells. The bacterial cells keep the active SPase I at the highest level in exponential growth phase suggesting that the selfcleavage may play an important role in regulating the activity of the enzyme under different conditions. Keywords Streptococcus pneumoniae signal peptidase I selfcleavage inactivation regulation. Many secreted and .

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