Abstract:To study the sequence characteristics of epimerization domain genes and their stereo-isomerization in the biosynthesis of non-ribosomal peptides, an epimerization domain gene was cloned from the genomic DNA of Streptomyces sp. X66. Bioinformatics analysis showed that the gene sequence length was 1,099 bp. Blast sequence alignment showed that the similarity between the cloned gene and the epimerization domain gene of Streptomyces albidoflavus strain W68 is 99.45%, and that the former has a typical functional region of the epimerization domain. It contains a unique conserved motif (HHxxxD) of the epimerization domain, which proves that the amplified gene fragment is an epimerization domain gene sequence. Physical and chemical analysis showed that it can encode 366 amino acids, and that its theoretical isoelectric point is 5.69. Its atomic composition, instability coefficient, and total average hydrophilicity were found to be C1752H2738N510O523S3, 32.68, and -0.15, respectively. Its coding product is an acidic hydrophilic stable protein without a signal peptide and transmembrane structure. The secondary structure of the protein comprises an α helix and random coil. SDS-PAGE showed that its molecular weight is about 55 ku, consistent with the expected value. By studying such epimerization domain genes, we hope to provide a scientific basis for the follow-up study of epimerization domain functions and the development of new non-ribosomal peptides.
