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The 65‐kDa protein derived from the internal translational start site of the clpA gene blocks autodegradation of ClpA by the ATP‐dependent protease Ti in Escherichia coli
Author(s) -
Seol Jae Hong,
Yoo Soon Ji,
Kang Man-Sik,
Ha Doo Bong,
Chung Chin Ha
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)01306-7
Subject(s) - proteolysis , protease , atp hydrolysis , escherichia coli , biochemistry , proteasome , serine protease , gene , biology , enzyme , chemistry , atpase
The ATP‐dependent protease Ti consists of two different components: ClpA containing ATP‐cleaving sites and ClpP having serine active sites for proteolysis. The clpA gene has dual translational start sites and therefore encodes two polypeptides with sizes of 84 and 65 kDa (referred to as ClpA84 and ClpA65, respectively). Here we show that ClpA84, but not ClpA65, is degraded in vitro by ClpP in the presence of ATP. The ClpP‐mediated hydrolysis of ClpA84 could be prevented by casein, which is an excellent substrate of protease Ti (i.e. ClpA84/ClpP complex). Thus, it appears that free form of ClpA84 competes with casein for the degradation by ClpA/ClpP complex. Furthermore, ClpA65 inhibited the auto‐degradation of ClpA84 by the complex. These results suggest that ClpA65 may play an important role in the control of the ClpA84 level and in turn in the regulation of ATP‐dependent protein breakdown in E. coli .