Send to

Choose Destination
J Biochem. 1996 Jul;120(1):98-103.

Purification and characterization of the Proteus vulgaris BlaA protein, the activator of the beta-lactamase gene.

Author information

Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo.


Induction of the expression of the beta-lactamase gene, blaB, is regulated by the blaA gene located just upstream of blaB in the opposite direction in Proteus vulgaris. The expression of the blaA gene is negatively autoregulated by its own product BlaA, the activator of the blaB gene. The P. vulgaris BlaA protein shares high amino acid homology with the LysR family members, which are prokaryotic transcriptional activators that possess a putative helix-turn-helix DNA binding motif. To characterize its function, we purified the BlaA protein to homogeneity from Escherichia coli carrying the expression plasmid of the blaA gene driven by the tac promoter. The gel shift assay and DNaseI footprinting showed that purified BlaA specifically bound to the blaA promoter region, which resides immediately upstream of that of blaB. The binding region contained an inverted repeat, including a T-N11-T sequence which is similar to the LysR motif (T-N11-A) that is conserved in some LysR family members [Goethals et al. (1992) Proc. Natl. Acad. Sci. USA 89, 1646-1650]. We also showed that the BlaA protein forms a dimer in solution, using glycerol gradient centrifugation and glutaraldehyde crosslinking.

[Indexed for MEDLINE]
Free full text

Supplemental Content

Full text links

Icon for Silverchair Information Systems Icon for J-STAGE, Japan Science and Technology Information Aggregator, Electronic
Loading ...
Support Center