Figure 4: LBS1 plays a critical role in yeast mitochondria ultrastructure and function.
From: Regulated membrane remodeling by Mic60 controls formation of mitochondrial crista junctions
(a) MICOS integrity in the indicated yeast strains was assessed by affinity chromatography experiments from isolated, digitonin-solubilized mitochondria. Load 5%, eluate 100%; see Supplementary Fig. 7 for uncropped images, Supplementary Table 2 for used antibodies and dilutions. (b) Yeast growth was assessed under respiratory conditions by spotting the indicated strains on agar plates containing lactate as sole carbon (SC) source. (c–f) Electron micrographs of yeast mitochondria in ultrathin cryo sections. Characteristic cristae connected to the boundary IM via CJs are seen in Mic60ProtA (top, left). Increased IM surface with stacked lamellar cristae sheets were detected in mic60Δ, Mic60_ΔLBS1ProtA and Mic60_RW433-434DDProtA mitochondria. Asterisks mark observed cristae. Scale bar, 500 nm. (g) Number of CJs in electron micrographs of mitochondrial sections from Mic60ProtA (Mic60ProtA, n=61) and MIC60 deletion yeast cells (mic60Δ, n=68) as well as cells expressing Mic60 variants with deleted LBS1 (ΔLBS1, n=39) or with LBS1 inactivated by individual amino acids substitutions (RW433-434DD, n=42). Error bars indicate the s.d. of each data set. (h,i) Complex III and complex IV activity of the indicated yeast strains were measured spectrophotometrically (n=3), error bars represent s.e.m. Mic60ProtA mitochondria pretreated with Antimycin A or KCN served as negative controls for complex III or complex IV activity, respectively.
