Mutagenesis of two N‐terminal Thr and five Ser residues in HslV, the proteolytic component of the ATP‐dependent HslVU protease

FEBS Letters

Shim, Yoon Kyung¹  Chung, Chin Ha¹  Kang, Man-Sik¹  Seong, Ihn Sik¹  Yoo, Soon Ji¹  Seol, Jae Hong¹ 

[1] Department of Molecular Biology and Research Center for Cell Differentiation, College of Natural Sciences, Seoul National University, Seoul 151-742, South Korea

关键词: ATP-dependent protease;    ATPase;    Heat shock protein;    HslVU;    20S proteasome;    Escherichia coli;   

DOI  :  10.1016/S0014-5793(97)00742-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

HslVU in E. coli is a new type of ATP-dependent protease consisting of two heat shock proteins: the HslU ATPase and the HslV peptidase that has two repeated Thr residues at its N terminus, like certain β-type subunit of the 20S proteasomes. To gain an insight into the catalytic mechanism of HslV, site-directed mutagenesis was performed to replace each of the Thr residues with Ser or Val and to delete the first or both Thr. Also each of the five internal Ser residues in HslV were replaced with Ala. The results obtained by the mutational analysis revealed that the N-terminal Thr acts as the active site nucleophile and that certain Ser residues, particularly Ser¹²⁴ and Ser¹⁷², also contribute to the peptide hydrolysis by the HslVU protease. The mutational studies also revealed that both Thr, Ser¹⁰³, and Ser¹⁷², but not Ser¹²⁴, are involved in the interaction of HslV with HslU and hence in the activation of HslU ATPase as well as in the HslVU complex formation.

【 授权许可】

Unknown