Two-dimensional polyacrylamide gel electrophoretic analysis of protein synthesis during aromatic acid catabolism by Streptomyces violaceusniger

• Main Author: Chow, Kevin Toshio
• Format: Others
• Language: English
• Published: 2009
• Online Access: http://hdl.handle.net/2429/4449

Streptomycetes were isolated from soil samples and screened for biodegradative activity against lignin-related aromatic compounds. One isolate, Streptomyces violaceusniger, efficiently utilized 4-hydroxy-3-methoxybenzoic acid (vanillate) and 4-hydroxybenzoic acid (p-hydroxybenzoate) as sole sources of carbon and energy. S. violaceusniger was able to biotransform indole to the dye indigo, indicative of aromatic dioxygenase activity. Colorimetric Rothera assays demonstrated the induction of aromatic dioxygenase activity in S. violaceusniger in the presence of vanillate and p-hydroxybenzoate. Twodimensional gel electrophoresis of total cell proteins revealed the synthesis of specific groups of proteins upon growth in the presence of vanillate, p-hydroxybenzoate or 3,4- dihydroxybenzoic acid (protocatechuate). The amino-terminal sequence of a heavily expressed 52 kDa protein, induced by vanillate andp-hydroxybenzoate, was highly similar to the amino-terminus of a hypothetical 55 kDa protein discovered during the course of the Escherichia coli genome sequencing project. The S. violaceusniger sequence aligns with conserved regions adjacent to nucleotide binding domains of the GTP-binding cc-subunit protein family and valyl-tRNA synthetases. Because biodegradative monooxygenases are known to possess nucleotide binding domains near the amino terminus and the protein is synthesized in such abundance, it is suggested that the 52 kDa protein is an enzyme involved in aromatic biodegradation. The results of this work are of interest to the study of lignin biodegradation, and also to the study of the catabolism of phenolic compounds in Streptomyces. === Science, Faculty of === Microbiology and Immunology, Department of === Graduate