Shotgun proteomics for the characterization of subunit composition of mitochondrial complex I.
Here we propose shotgun proteomics as an alternative method to gel-based bottom-up proteomic platform for the structural characterization of mitochondrial NADH:ubiquinone oxidoreductase (complex I). The approach is based on simultaneous identification of subunits after global digestion of the intact complex. Resulting mixture of tryptic peptides is purified, concentrated, separated and online analyzed using nano-scale reverse-phase nano-ESI-MS/MS in a single information dependent acquisition mode. The usefulness of the method is demonstrated in our work on the well described model system of complex I from bovine heart mitochondria. The shotgun method led to the identification and partial sequence characterization of 42 subunits representing more than 95% coverage of the complex. In particular, almost all nuclear (except MLRQ) and 5 mitochondria DNA encoded subunits (except ND4L and ND6) were identified. Furthermore, it was possible to identify 30 co-purified proteins of the inner mitochondrial membrane structurally not belonging to complex I. The method's efficiency is shown by comparing it to two classical 1 D gel-based strategies. Shotgun proteomics is less laborious, significantly faster and requires less sample material with minimal treatment, facilitating the screening for post-translational modifications and quantitative and qualitative differences of complex I subunits in genetic disorders.
Pocsfalvi
Gabriella
G
Proteomic and Biomolecular Mass Spectrometry Centre, Institute of Food Science and Technology, CNR, via Roma 52, a/c, 83100 Avellino, Italy. gpocsfalvi@isa.cnr.it
Cuccurullo
Manuela
M
Schlosser
Gitta
G
Cacace
Giuseppina
G
Siciliano
Rosa Anna
RA
Mazzeo
Maria Fiorella
MF
Scacco
Salvatore
S
Cocco
Tiziana
T
Gnoni
Antonio
A
Malorni
Antonio
A
Papa
Sergio
S
D000818:Animals; D002417:Cattle; D042967:Electron Transport Complex I / Q000737:chemistry*; D004591:Electrophoresis, Polyacrylamide Gel; D008929:Mitochondria, Heart / Q000737:chemistry*; D010449:Peptide Mapping; D021122:Protein Subunits / Q000032:analysis* / Q000737:chemistry; D040901:Proteomics; D020539:Sequence Analysis, Protein; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D021122:Protein Subunits; D042967:Electron Transport Complex I