This group dissipated from the ECF classification during the reclassification by [[Casas-Pastor et al.]]!

Taxonomical distribution

This group of σ factors is restricted to Bacteroidetes (Staroń et al., 2009).

Experimentally studied examples


Genomic context conservation

The ECF117 σ factors are putatively co-transcribed with their cognate anti-σ factors but the genomic context conservation does not extend beyond these.

Signaling mechanism

The putative ECF117 cognate anti-σ factor is a soluble protein containing a ZAS domain (Staroń et al., 2009), indicative of a regulatory mechanism relying on conformational changes. Nevertheless, experimental evidence supporting this hypothesis has so far not been gathered.

Physiological function



Members of ECF117 are part of ECF293, together with ECF13 and ECF101. 9.46% of the proteins from ECF293 have homology to original ECF117.


Staroń A, Sofia HJ, Dietrich S, Ulrich LE, Liesegang H, et al. 2009. The third pillar of bacterial signal transduction: classification of the extracytoplasmic function (ECF) sigma factor protein family. Molecular Microbiology 74 (3): 557–581.
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