Difference between revisions of "Part:BBa K932000"

Revision as of 18:04, 10 October 2012

OmpR234 under Tet Repressible Promoter

This part promotes the constitutive expression of the curli cluster (csgD), proteins involved in cell-cell adhesion.

Usage and Biology

Controlled by the tet repressible promoter, the EnvZ protein expresses constitutively in the absence of the TetR protein. EnvZ is a phosphorylase kinase involved in activation of OmpR, a transcription factor. OmpR activates the expression of the csgD operon, which codes for the curli proteins. These enzymes, once expressed on the outer membrane, assemble fibrous filaments involved in cell-surface and cell-cell adhesion. We expect expression of this part to enhance transcriptional activation of the curli proteins and consequent filament assembly. Cells containing this construct should aggregate more rapidly, thus becoming more amenable to the formation of biofilms.

SEM images of E. coli BL-21 DE3 cells not expressing (left) and expressing (right) BBa_K932000. Expression qualitatively enhances cellular aggregation.

Expression of the EnvZ protein under the tet promoter does not appear to affect growth.

Using the Thioflavin T fluorescence assay detailed by Shu, et al. PNAS 2012, we found that BL-21 E. coli cells express curli at significantly higher (p < 0.001, n = 6, T-test for comparison of means) than control cells.

Sequence and Features