The role of the tyrosine cluster and the walker A ATP binding motif of the protein Wzc in the production of emulsan in <i>Acinetobacter venetianus RAG-1</i>
Two regions of the wzc gene of Acinetobacter venetianus RAG-1 were investigated to understand their effects on the chain-length of the bioemulsifier emulsan. The Wzc protein is responsible for polymerization and export. When it is dephosphorylated, higher- molecular-weight exopolysaccharides result.
Point mutations in the walker A motif, the tyrosine autophosphorylation sites, and a combination of both were introduced into RAG-1 and the products excreted by these three variants were examined. The mutant in the autophosphorylation sites incorporated an unexpected frameshift which introduced a stop codon. The walker A mutant produced a low-molecular-weight polymer indicating that ATP binding in this region occurs through a separate mechanism than autophosphorylation on the 5-tyrosine residues. The mutant with both mutations was unable to carry out normal polymerization and export.
These results allow for further exploration of the ATP binding regulation mechanism for emulsan polymerization and the role of the N-terminus of Wzc.
0307: Molecular biology