Biochemical Characterization and Allosteric Modulation by Magnesium of (Na+, K+)-ATPase Activity in the Gills of the Red Mangrove Crab Goniopsis cruentata (Brachyura, Grapsidae)

Autor(es)

Moraes, Cintya M. ^[1] ; Lucena, Malson N. ^[2] ; Garcon, Daniela P. ^[3] ; Pinto, Marcelo R. ^[4] ; Fabri, Leonardo M. ^[1] ; Faleiros, Rogerio O. ^[5] ; Fontes, Carlos F. L. ^[6] ; McNamar, John C. ^{[7, 8]} ; Leone, Francisco A. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Dept Quim, Ave Bandeirantes 3900, BR-14040901 Ribeirao Preto, SP - Brazil

^[2] Univ Fed Mato Grosso, Inst Biociencias, Campo Grande, MS - Brazil

^[3] Univ Fed Triangulo Mineiro, Iturama, MG - Brazil

^[4] Univ Uberaba, Lab Biopatol & Biol Mol, Uberaba, MG - Brazil

^[5] Univ Fed Espirito Santo, Dept Ciencias Agr & Biol, Sao Mateus, ES - Brazil

^[6] Univ Fed Rio de Janeiro, Inst Bioquim Med Leopoldo de Meis, Rio De Janeiro, RJ - Brazil

^[7] Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Dept Biol, Ribeirao Preto, SP - Brazil

^[8] Univ Sao Paulo, Ctr Biol Marinha, Sao Sebastiao, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of Membrane Biology; v. 253, n. 3 MAY 2020.
• Citações Web of Science: 0

Resumo

We provide a kinetic characterization of (Na+, K+)-ATPase activity in a posterior gill microsomal fraction from the grapsid crab Goniopsis cruentata. (Na+, K+)-ATPase activity constitutes 95% of total ATPase activity, and sucrose density centrifugation reveals an ATPase activity peak between 25 and 35% sucrose, distributed into two, partially separated protein fractions. The (Na+, K+)-ATPase alpha-subunit is localized throughout the ionocyte cytoplasm and has an M-r of approximate to 10 kDa and hydrolyzes ATP obeying cooperative kinetics. Low (V-M = 186.0 +/- 9.3 nmol Pi min(-1) mg(-1) protein and K-0.5 = 0.085 +/- 0.004 mmol L-1) and high (V-M = 153.4 +/- 7.7 nmol Pi min(-1) mg(-1) protein and K-0.5 = 0.013 +/- 0.0006 mmol L-1) affinity ATP binding sites were characterized. At low ATP concentrations, excess Mg2+ stimulates the enzyme, triggering exposure of a high-affinity binding site that accounts for 50% of (Na+, K+)-ATPase activity. Stimulation by Mg2+ (V-M = 425.9 +/- 25.5 nmol Pi min(-1) mg(-1) protein, K-0.5 = 0.16 +/- 0.01 mmol L-1), K+ (V-M = 485.3 +/- 24.3 nmol Pi min(-1) mg(-1) protein, K-0.5 = 0.9 +/- 0.05 mmol L-1), Na+ (V-M = 425.0 +/- 23.4 nmol Pi min(-1) mg(-1) protein, K-0.5 = 5.1 +/- 0.3 mmol L-1) and NH4+ (V-M = 497.9 +/- 24.9 nmol Pi min(-1) mg(-1) protein, K-0.5 = 9.7 +/- 0.5 mmol L-1) obeys cooperative kinetics. Ouabain inhibits up to 95% of ATPase activity with K-I = 196.6 +/- 9.8 mu mol L-1. This first kinetic characterization of the gill (Na+, K+)-ATPase in Goniopsis cruentata enables better comprehension of the biochemical underpinnings of osmoregulatory ability in this semi-terrestrial mangrove crab. {[}GRAPHICS] . (AU)

• Processo FAPESP: 16/25336-0 - Estudo bioquímico comparativo da (Na+, K+)-ATPase branquial de Macrobrachium amazonicum (Heller, 1862) habitantes de regiões costeiras e continentais
• Beneficiário: Francisco de Assis Leone
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 13/24252-9 - O papel da (Na+,K+)-ATPase na capacidade osmorregulatória do caranguejo Ucides cordatus: uma abordagem bioquímica e molecular
• Beneficiário: Malson Neilson de Lucena
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado