ABSTRACT: Aiming at defining the protein content and composition of a single mitochondrion of Arabidopsis thaliana, shotgun analyses were performed on purified mitochondria from cultured heterotrophic Arabidopsis cells. Based on microscopic observations on the size of mitochondria, as well as biochemical properties, such as protein concentration, average molecular mass of proteins, and the average length of the signal peptide, intensity-based absolute quantification (iBAQ) values were applied to calculate the copy number of each identified protein species within a single mitochondrion. Copy numbers of the individual proteins span five orders of magnitude, ranging from >40,000 for Voltage-Dependent Anion Channel 1 (VDAC1) to sub-stoichiometric copy numbers, i.e. less than a single copy per single mitochondrion, for several pentatricopeptide repeat (PPR) proteins that modify mitochondrial transcripts. Aiming at defining the protein content and composition of a single mitochondrion of Arabidopsis thaliana, shotgun analyses were performed on purified mitochondria from cultured heterotrophic Arabidopsis cells. Based on microscopic observations on the size of mitochondria, as well as biochemical properties, such as protein concentration, average molecular mass of proteins, and the average length of the signal peptide, intensity-based absolute quantification (iBAQ) values were applied to calculate the copy number of each identified protein species within a single mitochondrion. Copy numbers of the individual proteins span five orders of magnitude, ranging from >40,000 for Voltage-Dependent Anion Channel 1 (VDAC1) to sub-stoichiometric copy numbers, i.e. less than a single copy per single mitochondrion, for several pentatricopeptide repeat (PPR) proteins that modify mitochondrial transcripts. Aiming at defining the protein content and composition of a single mitochondrion of Arabidopsis thaliana, shotgun analyses were performed on purified mitochondria from cultured heterotrophic Arabidopsis cells. Based on microscopic observations on the size of mitochondria, as well as biochemical properties, such as protein concentration, average molecular mass of proteins, and the average length of the signal peptide, intensity-based absolute quantification (iBAQ) values were applied to calculate the copy number of each identified protein species within a single mitochondrion. Copy numbers of the individual proteins span five orders of magnitude, ranging from >40,000 for Voltage-Dependent Anion Channel 1 (VDAC1) to sub-stoichiometric copy numbers, i.e. less than a single copy per single mitochondrion, for several pentatricopeptide repeat (PPR) proteins that modify mitochondrial transcripts.
Holger Eubel 
