A high-resolution reference map for cytoplasmic and membrane-associated proteins of Corynebacterium glutamicum

Abstract

We present a high-resolution reference map for soluble proteins obtained from Corynebacterium glutamicum cells grown in glucose minimal medium. The analysis window covers the p/ range from 4-6 and the molecular mass range from 5-100 kDa. Using overlapping narrow immobilized pH gradients for isoelectric focusing, 970 protein spots were detected after second-dimensional separation on SDS-polyacrylamide gels and colloidal Coomassie-staining. By tryptic peptide mass fingerprinting 169 protein spots were identified, representing 152 different proteins including many enzymes involved in central metabolism (18), amino acid biosynthesis (24) and nucleotide biosynthesis (11). Thirty-five of the identified proteins have no known function. A comparison of the observed and the expected physicochemical properties of the identified proteins indicated that nine proteins were covalently modified, since variants with apparently identical molecular mass, but differing p/ were detected. The N-termini of eight proteins were determined by post-source decay (PSD) analysis of selected peptides. In addition to the soluble proteins, a map of the membrane-bound proteins within the p/ range 4-7 is presented, which contains 660 protein spots, 22 of which were identified, representing 13 different proteins