Coenzyme Q (CoQ) is a key component of the mitochondrial respiratory chain,
but it also has several other functions in the cellular metabolism. One of
them is to function as an electron carrier in the reaction catalyzed by
sulfide:quinone oxidoreductase (SQR), which catalyzes the first reaction in
the hydrogen sulfide oxidation pathway. Therefore, SQR may be affected by CoQ
deficiency. Using human skin fibroblasts and two mouse models with primary CoQ
deficiency, we demonstrate that severe CoQ deficiency causes a reduction in
SQR levels and activity, which leads to an alteration of mitochondrial sulfide
metabolism. In cerebrum of Coq9R239X mice, the deficit in SQR induces an
increase in thiosulfate sulfurtransferase and sulfite oxidase, as well as
modifications in the levels of thiols. As a result, biosynthetic pathways of
glutamate, serotonin, and catecholamines were altered in the cerebrum, and the
blood pressure was reduced. Therefore, this study reveals the reduction in SQR
activity as one of the pathomechanisms associated with CoQ deficiency
syndrome