Plant and fungus calmodulins are polyubiquitinated at a single site in a Ca2+‐dependent manner

FEBS Letters

Ziegenhagen, R.¹  Jennissen, H.P.¹ 

[1] Institut für Physiologische Chemie, Universität-GHS-Essen, Hufelandstr. 55, D-4300 Essen 1, FRG

关键词: Plant calmodulin;    Ubiquitin;    Calmodulin-ubiquitin conjugate;    Protein ubiquitination;    ATP-dependent proteolysis;    Trimethyllysine;   

DOI  :  10.1016/0014-5793(90)81097-8

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

In plants Ca²⁺ plays a crucial role as second messenger. Thus calmodulin is one of the most important signal transducing molecules for metabolic regulation in plants. Previously we showed that bovine testis calmodulin can be covalently coupled at one site to ubiquitin in a Ca²⁺-dependent manner in the presence of ATP/Mg²⁺ by ubiquityl-calmodulin synthetase. Since calmodulin from spinach has 13 amino acid sequence differences to bovine calmodulin - two of them in Ca²⁺-binding loops - it was unclear, whether a conjugation of ubiquitin to this molecule would be possible. In this paper it is shown that calmodulin from spinach and a similar calmodulin from the mold Neurospora crassa can be covalently conjugated to ubiquitin in a Ca²⁺-dependent manner. It is shown that higher molecular mass conjugates containing up to three ubiquitin molecules per calmodulin are obtained. Experiments with methylated ubiquitin demonstrate that, as with vertebrate calmodulins, only one lysine residue is linked to ubiquitin and that the incorporation of addditional ubiquitin molecules leads to a polyubiquitin chain.

【 授权许可】

Unknown