A Mitochondrial Membrane Exopolyphosphatase Is Modulated by, and Plays a Role in, the Energy Metabolism of Hard Tick Rhipicephalus (Boophilus) microplus Embryos

International Journal of Molecular Sciences

Eldo Campos³  Arnoldo R. Fa๺nha¹  Evenilton P. Costa²  Amanda Fraga³  Jorge Moraes³  Itabajara da Silva Vaz¹  Aoi Masuda¹ 

[1] Instituto Nacional de Ciência e Tecnologia—Entomologia Molecular, Rio de Janeiro, RJ, CEP 21941–590, Brazil; E-Mails:;Laboratório de Química e Função de Proteínas e Peptídeos, Laboratório de Biologia Celular e Tecidual and Unidade de Experimentação Animal–CBB–UENF, Avenida Alberto Lamego, 2000, Horto, Campos dos Goytacazes, RJ, CEP 28015–620, Brazil; E-Mail:;Laboratório Integrado de Bioquímica—Hatisaburo Masuda, UFRJ, Polo Barreto, Rua Rotary Club s/n, São José do Barreto, Macaé, RJ, C.P. 119.331, CEP 27971–220, Brazil; E-Mails:

关键词: inorganic polyphosphate;    respiration;    membrane exopolyphosphatase;    arthropod;    energy metabolism;   

DOI  :  10.3390/ijms12063525

来源: mdpi

【 摘 要 】

The physiological roles of polyphosphates (polyP) recently found in arthropod mitochondria remain obscure. Here, the relationship between the mitochondrial membrane exopolyphosphatase (PPX) and the energy metabolism of hard tick Rhipicephalus microplus embryos are investigated. Mitochondrial respiration was activated by adenosine diphosphate using polyP as the only source of inorganic phosphate (P_i) and this activation was much greater using polyP₃ than polyP₁₅. After mitochondrial subfractionation, most of the PPX activity was recovered in the membrane fraction and its kinetic analysis revealed that the affinity for polyP₃ was 10 times stronger than that for polyP₁₅. Membrane PPX activity was also increased in the presence of the respiratory substrate pyruvic acid and after addition of the protonophore carbonyl cyanide-p-trifluoromethoxyphenylhydrazone. Furthermore, these stimulatory effects disappeared upon addition of the cytochrome oxidase inhibitor potassium cyanide and the activity was completely inhibited by 20 μg/mL heparin. The activity was either increased or decreased by 50% upon addition of dithiothreitol or hydrogen peroxide, respectively, suggesting redox regulation. These results indicate a PPX activity that is regulated during mitochondrial respiration and that plays a role in adenosine-5′-triphosphate synthesis in hard tick embryos.

【 授权许可】

CC BY   
© 2011 by the authors; licensee Molecular Diversity Preservation International, Basel, Switzerland.