Anti-sigmas for Programmable Transcriptional Regulation

Technology #15523

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FIG. 1 depicts a strategy for the genomic mining of Extracytoplasmic Function (ECF) σs, anti-σs, and promoters. FIG. 1A shows how sigmas recruit core RNA polymerase (RNAP) to promoters; a function that is inhibited by the anti-σ. Sigmas have a two-domain structure that binds to the −10 and −35 regions of the target promoter. FIG. 1B shows the complete libraries of 86 synthesized σs (top row) and their 62 cognate anti-σs (bottom row) organized as a phylogenetic tree. Asterisks indicate active σs (>5-fold activation) or anti-σs (>2-fold repression). Carets indicate σs or anti-σs that appear in the final orthogonal sets. All σs in the library are named ECFXX_YYYY, where “XX” denotes the ECF subgroup, and “YYYY” denotes the unique σ ID given by Staron and co-workers7. The anti-σs were named ASXX_YYYY, where “XX” and “YYYY” denote the ECF subgroup and unique ID of the cognate σ. Consequently, cognate σ/anti-σ pairs have the same numbering (e.g., ECF11—987 and AS11—987). FIG. 1C shows that for each σ, target promoters are identified through a process of computational search, selection, and design. The first step involves the organization of the ECF operons according to the subgroups defined by Mascher and co-workers.
Professor Christopher Voigt
Department of Biological Engineering, MIT
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Virgil Rhodius
University of California, San Francisco
Carol Gross
University of California, San Francisco
Managed By
Jon Gilbert
MIT Technology Licensing Officer
Patent Protection

Anti-sigmas for programmable transcriptional regulation

US Patent Pending 2015-0051112


This invention enables better control of large genetic circuits in synthetic biology.

Problem Addressed

There are only a few well characterized transcription factors with which to program genetic circuits in synthetic biology. This invention is a novel system which can be used to "wire-together" components of genetic circuits, enabling independent control of each component.


ECF sigmas (extracytoplasmic function) are similar to transcription factors, and enable directed expression of target genes by recognizing specific promoters. Anti-sigmas are proteins that bind to specific ECF sigmas and serve to block their ability to direct transcription from target promoters. This reaction is highly specific due to high-binding constants.  The inventors have assembled a library of ECF sigmas and anti-sigmas, which, in conjunction with promoters, can dramatically expand the ability to design and construct large genetic circuits. The ability to both positively and negatively regulate specific parts of a circuit enables independent control of target modules and provides the ability to integrate multiple input signals to generate desired output. These novel genetic circuits are an effective mechanism to regulate gene expression.


  • High specificity
  • Positive and negative circuit regulation