Processing of metacaspase 2 from Trypanosoma brucei (TbMCA2) broadens its substrate specificity.

Autor: Gilio JM; Departmento de Biofísica, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Pedro de Toledo, 669 - 7° andar, São Paulo, Brazil., Marcondes MF; Departmento de Biofísica, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Pedro de Toledo, 669 - 7° andar, São Paulo, Brazil., Ferrari D; Centro Interdisciplinar de Investigação Bioquímica (CIIB), Universidade de Mogi das Cruzes, Av. Cândido Xavier de Almeida e Souza, 200, Mogi das Cruzes, SP, Brazil., Juliano MA; Departmento de Biofísica, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Pedro de Toledo, 669 - 7° andar, São Paulo, Brazil., Juliano L; Departmento de Biofísica, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Pedro de Toledo, 669 - 7° andar, São Paulo, Brazil., Oliveira V; Departmento de Biofísica, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Pedro de Toledo, 669 - 7° andar, São Paulo, Brazil., Machado MFM; Departmento de Biofísica, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Pedro de Toledo, 669 - 7° andar, São Paulo, Brazil; Centro Interdisciplinar de Investigação Bioquímica (CIIB), Universidade de Mogi das Cruzes, Av. Cândido Xavier de Almeida e Souza, 200, Mogi das Cruzes, SP, Brazil. Electronic address: mauriciomachado@umc.br.
Jazyk: angličtina
Zdroj: Biochimica et biophysica acta. Proteins and proteomics [Biochim Biophys Acta Proteins Proteom] 2017 Apr; Vol. 1865 (4), pp. 388-394. Date of Electronic Publication: 2017 Jan 09.
DOI: 10.1016/j.bbapap.2017.01.002
Abstrakt: Metacaspases are members of the cysteine peptidase family and may be implicated in programmed cell death in plants and lower eukaryotes. These proteases exhibit calcium-dependent activity and specificity for arginine residues at P 1 . In contrast to caspases, they do not require processing or dimerization for activity. Indeed, unprocessed metacaspase-2 of Trypanosoma brucei (TbMCA2) is active; however, it has been shown that cleavages at Lys 55 and Lys 268 increase TbMCA2 hydrolytic activity on synthetic substrates. The processed TbMCA2 comprises 3 polypeptide chains that remain attached by non-covalent bonds. Replacement of Lys 55 and Lys 268 with Gly via site-directed mutagenesis results in non-processed but enzymatically active mutant, TbMCA2 K55/268G. To investigate the importance of this processing for the activity and specificity of TbMCA2, we performed activity assays comparing the non-processed mutant (TbMCA2 K55/268G) with the processed TbMCA2 form. Significant differences between TbMCA2 WT (processed form) and TbMCA2 K55/268G (non-processed form) were observed. Specifically, we verified that although non-processed TbMCA2 is active when assayed with small synthetic substrates, the TbMCA2 form does not exhibit hydrolytic activity on large substrates such as azocasein, while processed TbMCA2 is able to readily digest this protein. Such differences can be relevant for understanding the physiological regulation and function of TbMCA2.
(Copyright © 2017 Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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