ECF17

ECF subgroups

ECF17s1 454 ECF17s2 498 ECF17s3 209 ECF17s4 206 ECF17s5 154 ECF17s6 163 ECF17s7 99 ECF17s8 94 ECF17s9 73 ECF17s10 61 ECF17s11 64 ECF17s12 41 ECF17s13 31 ECF17s14 26 ECF17s15 27 ECF17s16 25 ECF17s17 26 ECF17s18 22 ECF17s19 28 ECF17s20 29 ECF17s21 18 ECF17s22 23 ECF17s23 17 ECF17s24 17 ECF17s25 14 ECF17s26 17 ECF17s27 24 ECF17s28 13 ECF17s29 14 ECF17s30 17 ECF17s31 15 ECF17s32 9 ECF17s33 14 ECF17s34 20 ECF17s35 12 ECF17s36 14 ECF17s37 14 ECF17s38 10 ECF17s39 12 ECF17s40 11

ECF proteins

General description: Group ECF17 is composed of 85.82% of proteins with homology to the original group ECF17. All the proteins are present in Actinobacteria.

Anti-σ factors: Members of ECF17 might be regulated by putative AS factors with a zinc-finger and one transmembrane helix (83.33%). Putative AS factors are encoded in position +1, except in ECF17s1, where it is located mainly in position +2. Subgroups ECF17s18 and ECF17s19 lack of putative AS factors in their genetic context. Indeed, previous studies identified this protein as an AS factor previous studies (Gordon et al., 2008; Hahn, Raman, Anaya, & Husson, 2005; Staroń et al., 2009).

Genomic context conservation: Aside from the AS factor, the remaining conserved proteins are subgroup-specific. ECF17s1 contains a conserved protein with a bacterial capsule synthesis protein PGA_cap (Pfam: PGA_cap) in position -1, a conserved formamidopyrimidine-DNA glycosylase, a universal stress protein, and a sortase. ECF17s2 and ECF17s11 contain a conserved protein from the Major Facilitator Superfamily (MFS). Consequent with this conserved genomic context, the only described member of ECF17s2, SigU from Streptomyces coelicolor is involved in response to envelope stress and morphological differentiation (Xu & Min, 2011). ECF17s4 contains a conserved metallopeptidase from family M24 in position -1, an adenylate kinase in position -2, a SecY translocase in position -3 and ~2 copies of a leucine carboxyl methyltransferase. Lastly, ECF17s11 encodes a secreted protein in position -1 and members of ECF17s18 encode a conserved N-acetylmuramoyl-L-alanine amidase in their genetic context.

Studied members: The genetic context of ECF17s4 agrees with the function of its only characterized member, SigL from M. tuberculosis, which is involved in the synthesis of envelope lipids, extracytoplasmic protein modification, and pathogenesis, although none of the genes in its genetic neighborhood are regulated by SigL (Jogler et al., 2012).

Promoter motif conservation: Promoter motifs are conserved, with the consensus TGAACC in -35 and CGT in -10, although other variations are possible in some subgroups. These consensus promoter motifs agree with reports of original ECF17 (Staroń et al., 2009) and with experimental data from SigL (Hahn, Raman, Anaya, & Husson, 2005) and SigU (Gordon et al., 2008).

Summary: ECF17 is regulated by anti-σ factors. The conservation of the promoter motifs indicates that it auto-induces its expression in most of the cases. Indeed, this is the case for SigL (Hahn et al., 2005) and SigU (Gordon et al., 2008). It is possible that proteases encoded near ECFs from ECF17 are in charge of the degradation of their cognate anti-σ factor. The functions of members of ECF17 are diverse, and it does seem to be the main factor that contributes to their sequence similarity.