Studied members: One member of ECF291, CnrH from Cupriavidus metallidurans (ECF291s9), has been experimentally addressed. CnrH is encoded as part of a metal resistance determinant that includes cnrYHX and cnrCBAT operons (Grass, Fricke, & Nies, 2005). CnrH is sequestered by the AS factor CnrY, encoded in -2 from the ECF (Maillard et al., 2014). CnrY is a type II AS factor since it only contains two transmembrane helices that wrap around the ECF protein (Maillard et al., 2014). CnrX, the transmembrane heavy metal resistance protein encoded in -1, serves as the periplasmic sensor of Ni2+ or Co2+ (Trepreau et al., 2011). Upon sensing of these metals, CnrY in inhibited by an unknown mechanism and CnrH (Maillard et al., 2014). CnrH then directs the RNAP towards the cnrYXH promoter and the cnrCBA efflux pump, which secretes heavy metals (Grass et al., 2005).
Genomic context conservation: Indeed, this metal resistance determinant is conserved in our analysis of the genetic neighborhood of members of ECF291. Proteins from ECF291 encode a multicopper oxidase in +2, a copper resistance protein B precursor (CopB) in +2, a heavy metal resistance protein in -1. Members of ECF291s1 and ECF291s4 also encode CopC in 3 and CopD in -4. The Pfam domain of CnrY is only conserved in ECF291s9 and ECF291s12. Nevertheless, it is known that AS factors of this type have a variable sequence (Maillard et al., 2014) and the proteins in -2 of the rest of the groups contain one transmembrane helix (81.4%), have homology to AS factors from the original classification (Staroń et al., 2009) and align well with the CnrY-like AS factors from ECF291s9 and ECF291s12. Other conserved proteins include a LuxR transcriptional regulator fused to a response regulator receiver domain (ECF291s1), a TonB dependent receptor (ECF291s4) and an E1-E2 ATPase.
Promoter motif conservation: Predicted target promoter motifs are only conserved in some subgroups such as ECF291s1, where there is TCTCC in -35 and TACGCA in -10. These motifs do not agree with the original group ECF20 (Rhodius et al., 2013). CnrH regulates the transcription of its operon, cnrYXH, in C. metallidurans (Grass et al., 2005).
Summary: Members of ECF291 are in charge of heavy metal resistance since they upregulate the expression of an efflux complex synthesized in coding sequences from +1 to +4. Members of this group are regulated by single-transmembrane helix AS factors encoded in -2 with homology to CnrY from C. metallidurans and a transmembrane protein with a heavy metal resistance domain encoded in -1 with homology to CnrX in C. metallidurans, which serves as a periplasmic sensor of the Ni2+ or Co2+.
Number of representative ECFs: 566
Number of non-redundant ECFs: 388
Sequences with C-terminal extension: 0.00%
Sequences with N-terminal extension: 0.00%
Overrepresented phylum: Proteobacteria [95.23%]
|Control of expression of a periplasmic nickel efflux pump by periplasmic nickel concentrations.||Biometals : an international journal on the role of metal ions in biology, biochemistry, and medicine||2005||G. Grass, B. Fricke, D. Nies||PubMed: 16158236||ECF291|
|The third pillar of bacterial signal transduction: classification of the extracytoplasmic function (ECF) sigma factor protein family.||Molecular microbiology||2009||A. Staroń, H. Sofia, S. Dietrich, L. Ulrich, H. Liesegang, T. Mascher||PubMed: 19737356||ECF103, ECF21, ECF123, ECF51, ECF39, ECF281, ECF102, ECF130, ECF122, ECF291, ECF15, ECF242, ECF22, ECF285, ECF106, ECF27, ECF31, ECF240, ECF114, ECF16, ECF38, ECF41, ECF105, ECF116, ECF111, ECF03, ECF239, ECF42, ECF294, ECF17, ECF11, ECF29, ECF235, ECF293, ECF118, ECF265, ECF30, ECF23, ECF14, ECF249, ECF18, ECF115, ECF290, ECF25, ECF121, ECF02, ECF120, ECF289, ECF28, ECF243, ECF19, ECF43, ECF107, ECF12, ECF32, ECF36, ECF292, ECF286, ECF271, ECF26, ECF40, ECF56, ECF33|
|Structural basis for metal sensing by CnrX.||Journal of molecular biology||2011||J. Trepreau, E. Girard, A. Maillard, E. de Rosny, I. Petit-Haertlein, R. Kahn, J. Covès||PubMed: 21414325||ECF291|
|Design of orthogonal genetic switches based on a crosstalk map of σs, anti-σs, and promoters.||Molecular systems biology||2013||V. Rhodius, T. Segall-Shapiro, B. Sharon, A. Ghodasara, E. Orlova, H. Tabakh, D. Burkhardt, K. Clancy, T. Peterson, C. Gross, C. Voigt||PubMed: 24169405||ECF22, ECF27, ECF03, ECF21, ECF39, ECF25, ECF26, ECF42, ECF38, ECF14, ECF29, ECF33, ECF281, ECF290, ECF291|
|The crystal structure of the anti-σ factor CnrY in complex with the σ factor CnrH shows a new structural class of anti-σ factors targeting extracytoplasmic function σ factors.||Journal of molecular biology||2014||A. Maillard, E. Girard, W. Ziani, I. Petit-Härtlein, R. Kahn, J. Covès||PubMed: 24727125||ECF291|