CRYSTALLINE MITOCHONDRIAL INCLUSION-BODIES ISOLATED FROM CREATINE DEPLETED RAT SOLEUS MUSCLE

Rats were fed a 2% guanidino propionic acid diet for up to 18 weeks to induce cellular creatine depletion by inhibition of creatine uptake b y this creatine analogue. Ultrastructural analysis of creatine deplete d tissues showed that mitochondrial intermembrane inclusion bodies app eared in all skeletal muscles analysed, after 11 weeks of feeding, Hea rt had relatively few even after 18 weeks of analogue feeding and none were evident in kidney, brain or liver, These structures were strongl y immune-positive for sarcomeric mitochondrial creatine kinase and upo n removal from mitochondria, the inclusion bodies were shown to diffra ct to a resolution of 2.5 nm, Two-dimensional image analysis and three -dimensional reconstruction revealed arrays of creatine kinase octamer s with additional components between the octameric structures, The sam e mitochondria had a 3-fold higher extractable specific creatine kinas e activity than controls. Molecular mass gel filtration of inclusion b ody containing mitochondrial extracts from analogue fed rat solei reve aled mitochondrial creatine kinase eluting as an aggregate of an appar ent molecular mass greater than or equal to 2,000 kDa, Mitochondrial c reatine kinase of control soleus mitochondrial extract eluted as an oc tamer, with a molecular mass of 340 kDa, Respiration measurements of c ontrol solei mitochondria displayed creatine mediated stimulation of o xidative phosphorylation that was absent in analogue-fed rat solei mit ochondria, The latter also had 19% and 14% slower rates of state 4 and maximal state 3 respiration, respectively, than control mitochondria, These results indicate that mitochondrial creatine kinase co-crystall ises with another component within the inter membrane space of select mitochondria in creatine depleted skeletal muscle, and is inactive in situ.