ECF25

ECF subgroups

ECF25s1 187 ECF25s2 27 ECF25s3 27 ECF25s4 34 ECF25s5 17 ECF25s6 19 ECF25s7 13 ECF25s8 37 ECF25s9 14 ECF25s10 18 ECF25s11 14 ECF25s12 22 ECF25s13 17 ECF25s14 16 ECF25s15 6 ECF25s16 12 ECF25s17 20 ECF25s18 11 ECF25s19 14 ECF25s20 10

ECF proteins

General description: Two subgroups of ECF25, ECF25s1 and ECF25s11, have homology to original ECF25 (30.6%) and ECF20 (0.19%). ECF25 is one of the most diverse ECF groups in terms of taxonomic origin of the sequences. Proteins from ECF25 are present mainly in Cyanobaceria (ECF25s1 and ECF25s11, 50%), but also in Firmicutes (11.88%), Deltaproteobacteria (15.84%), Spirochaetes (ECF25s3, 2.97%), Fibrobacteres (ECF25s13, 0.5%), Nitrospirae (ECF25s12, 0.5%), Deinococcus-Thermus (ECF25s5, 6.44%), Chloroflexi (ECF25s17, ECF25s18 and ECF25s19, 6.44%), Gemmatimonadetes (ECF25s4, 1%), Ignavibacteriae (ECF25s9, 1%), Acidobacteria (1%) , Bacteroidetes (1.98%), and Calditrichaeota (0.5%).

Anti-σ factor: Similarly to original ECF25 (Staroń et al., 2009), proteins from ECF25 contain a putative AS factor in position +1, which are mainly single membrane-pass (74.75%). Nevertheless, variants with two or three transmembrane helices are possible. For instance, putative AS factors from Firmicutes order Thermoanaerobacterales (ECF25s14), and Chloroflexi (ECF25s16, ECF25s18, ECF25s19) contain two transmembrane helices, and proteins ECF25s20 contain three transmembrane helices. These putative AS factors typically contain a zinc-binding domain and/or a DUF4384 or a DUF4349.

Genomic context conservation: Other proteins conserved in the genetic neighborhood of ECF25 are a transglycosylase SLT from phages, T2SS, T3SS or T4SS (ECF25s2), a DNA polymerase family A with 5'-3' exonuclease activity involved in DNA repair (ECF25s2), a dephospho-CoA kinase (ECF25s2), a DUF1800 (ECF25s5) and an iron-dependent repressor (ECF25s5).

Studied members: The only member of ECF25 experimentally addressed, SigG from Nostoc punctiforme (ECF25s1) is in charge of the defense against cell wall stress arising from external sources (EDTA, heat, lysozyme, cold) or cellular differentiation (Bell, Lee, & Summers, 2017). SigG is regulated by a single membrane pass AS factor SapG.

Promoter motif conservation: The predicted target promoter motifs of ECF25s1 and ECF25s2 are GGAAC in -35 and GTC in -10. This promoter motif is similar to the original group ECF25 (Rhodius et al., 2013) and the binding motif of SigG in N. punctiforme (Bell et al., 2017).

Summary: ECF25 is regulated by AS factors located in +1 and seem to be involved in cell wall homeostasis.