Variable intron/exon structure in the oligochaete lombricine kinase gene

Lombricine kinase is an annelid enzyme that belongs to the phosphagen kinase family of which creatine kinase and arginine kinase are the typical representatives. The enzymes play important roles in the cellular energy metabolism of animals. Biochemical, physiological and molecular information with respect to lombricine kinase is limited compared to other phosphagen kinases. This study presents data on the cDNA sequences of lombricine kinase from two smaller oligochaetes, Enchytraeus sp. and Stylaria sp. The deduced amino acid sequences are analyzed and compared with other selected phosphagen kinases. The intron/exon structure of the lombricine kinase gene was determined for these two species as well as two additional oligochaetes, Lumbriculus variegatus and Tubifex tubifex, and compared with available data for annelid phosphagen kinases. The data indicate the existence of a variable organization of the proposed 8-intron/9-exon gene structure. The results provide further insights in the evolution and position of these enzymes within the phosphagen kinase family.     

Disturbance of brain energy and redox homeostasis provoked by sulfite and thiosulfate: Potential pathomechanisms involved in the neuropathology of sulfite oxidase deficiency

Sulfite oxidase (SO) deficiency is biochemically characterized by tissue accumulation and high urinary excretion of sulfite, thiosulfate and S-sulfocysteine. Affected patients present severe neurological symptoms and cortical atrophy, whose pathophysiology is still poorly established. Therefore, in the present work we investigated the in vitro effects of sulfite and thiosulfate on important parameters of energy metabolism in the brain of young rats. We verified that sulfite moderately inhibited the activity of complex IV, whereas thiosulfate did not alter any of the activities of the respiratory chain complexes. It was also found that sulfite and thiosulfate markedly reduced the activity of total creatine kinase (CK) and its mitochondrial and cytosolic isoforms, suggesting that these metabolites impair brain cellular energy buffering and transfer. In contrast, the activity of synaptic Na⁺,K⁺-ATPase was not altered by sulfite or thiosulfate. We also observed that the inhibitory effect of sulfite and thiosulfate on CK activity was prevented by melatonin, reduced glutathione and the combination of both antioxidants, as well as by the nitric oxide synthase N^ω-nitro-l-arginine methyl ester, indicating the involvement of reactive oxygen and nitrogen species in these effects. Sulfite and thiosulfate also increased 2′,7′-dichlorofluorescin oxidation and hydrogen peroxide production and decreased the activity of the redox sensor aconitase enzyme, reinforcing a role for oxidative damage in the effects elicited by these metabolites. It may be presumed that the disturbance of cellular energy and redox homeostasis provoked by sulfite and thiosulfate contributes to the neurological symptoms and abnormalities found in patients affected by SO deficiency.