The influence of the acyl chain composition of cardiolipin on the stability of mitochondrial complexes; an unexpected effect of cardiolipin in alpha-ketoglutarate dehydrogenase and prohibitin complexes.
The role of cardiolipin acyl chain composition in assembly/stabilization of mitochondrial complexes was investigated using three yeast deletion mutants (acb1Delta strain; taz1Delta strain; and acb1Deltataz1Delta strain). Deletion of the TAZ1 gene, involved in cardiolipin acyl chain remodeling, is known to increase the content of monolyso-cardiolipin (MLCL) at the expense of CL, and to decrease the unsaturation of the remaining CL. Deletion of the ACB1 gene encoding the acyl-CoA-binding protein, involved in fatty acid elongation, decreases the average length of the CL acyl chains. Furthermore, a TAZ1ACB1 double deletion mutant strain was used in this study which has both a decrease in the length of the CL acyl chains and an increase in MLCL. BN/SDS PAGE analysis revealed that cardiolipin is important for the prohibitin-m-AAA protease complex, the alpha-ketoglutarate dehydrogenase complex and respiratory chain supercomplexes. The results indicate that the decreased level of complexes in taz1Delta and acb1Deltataz1Delta mitochondria is due to a decreased content of CL or the presence of MLCL.