General description: Members of ECF16 are present in Proteobacteria (96.5%), mainly Alphaproteobacteria, and ECF16s14 to Spirochaetes (2.67%). All the subgroups contain proteins with homology to original ECF16 (85.71%).
Anti-σ factor: Proteins from ECF16 are regulated by a putative AS factor with a conserved DUF1109 encoded in position +1. This protein contains six transmembrane helices (95.8%) and two conserved cysteine residues, as in the experimentally addressed AS factors of ECF16.
Genomic context conservation: Other conserved proteins in the genetic context of members of ECF16 are a DUF692-containing protein (ECF16s15 and ECF16s16) a DUF2282-containing protein (ECF16s15 and ECF16s16), a DoxX-domain containing protein (ECF16s15 and ECF16s16), an enoyl-CoA hydratase/isomerase (ECF16s2), a putative DNA-binding domain (ECF16s16), a cytochrome C biogenesis protein fused to a thioredoxin-like domain (ECF16s10), a AhpC/TSA family (ECF16s10), an outer membrane efflux protein (ECF16s2), a glutathione S-transferase (ECF16s19) and a protein from the AcrB/AcrD/AcrF family (ECF16s5).
Studied examples: Some members of ECF16, SigF from Caulobacter crescentus and Bradyrhizobium japonicum, have been functionally addressed. They are regulated by an AS factor (NrsF from C. crescentus and OsrA from B. japonicum) with six transmembrane helices and two cysteine residues facing the periplasm that are essential for sequestering their cognate ECF σ factor (Jogler et al., 2012).
Promoter motif conservation: Members of this group respond to heavy-metal stress (Jogler et al., 2012) or oxidative stress (Jogler et al., 2012). Both SigF from C. crescentus (ECF16s20) and B. japonicum (ECF16s2) self-induce their expression, and SigF from C. crescentus has the target promoter GTAACC-CGTA (Kohler et al., 2012; Masloboeva et al., 2012). These data do not agree with the predicted promoter elements (normally TTC in -35 and TAC or TAAC in -10).
Summary: Members of ECF16 are associated with DUF1109-containing AS factors with six transmembrane helices and conserved periplasmic cysteine residues. Their promoter motifs, although conserved, do not match experimental data. Members of ECF16 are involved in heavy metal and oxidative stress response.
Number of representative ECFs: 1590
Number of non-redundant ECFs: 1715
Sequences with C-terminal extension: 0.12%
Sequences with N-terminal extension: 11.60%
Overrepresented phylum: Proteobacteria [97.80%]
|A caulobacter crescentus extracytoplasmic function sigma factor mediating the response to oxidative stress in stationary phase.||Journal of bacteriology||2006||C. Alvarez-Martinez, R. Baldini, S. Gomes||PubMed: 16484194||ECF16|
|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|
|Reactive oxygen species-inducible ECF σ factors of Bradyrhizobium japonicum.||PloS one||2012||N. Masloboeva, L. Reutimann, P. Stiefel, R. Follador, N. Leimer, H. Hennecke, S. Mesa, H. Fischer||PubMed: 22916258||ECF16, ECF33|
|Extracytoplasmic function (ECF) sigma factor σF is involved in Caulobacter crescentus response to heavy metal stress.||BMC microbiology||2012||C. Kohler, R. Lourenço, G. Avelar, S. Gomes||PubMed: 22985357||ECF16|