Differential proteome analysis and mass spectrometric characterization of germ line development-related proteins of Caenorhabditis elegans

Proteome maps and differences of protein patterns of the synchronized larval stage L4 of the temperature‐sensitive Caenorhabditis elegans (C. elegans) glp‐1 mutant (e2144ts) were investigated after cultivation at 15°C (developing a normal phenotype) or 25°C (developing a mutated phenotype) by two‐dimensional gel electrophoresis (2‐DE) and matrix‐assisted laser desorption/ionization (MALDI)‐mass spectrometry. From the 183 identified protein spots six proteins were found differently expressed. The Vit‐6 vitellogenin (CE28594), the hypothetical 17.2 protein (CE25224), the hypothetical 17.4 protein (CE16999), and the heat shock protein 16 kDa (CE14249) were more abundant when growing worm cultures at 25°C. By contrast, the nucleoside diphosphate kinase (CE09650) was found increased at 15°C. Most notably, the eukariotic initiation factor 5A‐1 (CE00503), highly abundant at 15°C, was not present in cultures grown at 25°C. Its absence at 25°C can not be attributed to lack of the enzymatic machinery that is necessary for hypusinylation. Instead, a direct downstream effect of the lack of functionality of GLP‐1 may cause the expression of this protein. The yolk proteins 115 kDa and 88 kDa were attributed by mass spectrometric protein structure analysis as C‐terminal and N‐terminal fragments of the Vit‐6 vitellogin protein (CE28594), respectively. The cleavage site between both derivatives was located between R764 and A768. A conflict in the database sequences at amino acid positions 1622 and 1623 of vitellogenin‐6 was solved by mass spectrometric sequence analysis. The combination of 2‐DE with mass spectrometry enabled the identification of mutation‐associated differences on somatic gonadal cell and germ line cell development‐associated proteins.