Proteolytic activity of plum pox virus—tobacco etch virus chimeric NIa proteases

FEBS Letters

Lain, Sonia¹  Garcia, Juan Antonio¹ 

[1] Centro de Biologia Molecular (CSIC-UAM), Universidad Autónoma de Madrid, Canto Blanco, 28049 Madrid, Spain

关键词: Viral protease;    Potyvirus;    Chimeric proteins;   

DOI  :  10.1016/0014-5793(91)80360-F

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Plasmids encoding chimeric NI_a-type proteases made of sequences from the polyviruses plum pox virus (PPV) and tobacco etch virus (TEV) have been constructed. Their proteolytic activity on the large nuclear inclusion protein (NI_a)-capsid protein (CP) junction of each virus was assayed in Escherichia coli cells. The amino half of the protease seemed to be involved neither in the enzymatic catalysis nor in substrate recognition. In spite of the large homology among the PPV and TEV NI_a-type proteases, the exchange of fragments from the carboxyl halves of the molecules usually caused a drastic decrease in the enzymatic activity. Inactive chimeric proteases did not interfere with cleavage by PPV wild type protease expressed from a second plasmid. The results suggest that the recognition and catalytic sites of the NI_a proteases are closely interlinked and, although residues relevant for the correct interaction with the substrate could be present in other parts of the protein, a main determinant for substrate specificity should lie in a region situated, approximately, between positions 30 and 90 from the carboxyl end. This region includes the conserved His at position 360 of PPV or 355 of TEV, which has been postulated to interact with the Gin at position −1 of the cleavage sites.

【 授权许可】

Unknown