General description: The proteins from ECF51 could be classified against original ECF51 (97.9%), except ECF51s15, which contains ~50 amino acid N-terminal extension. Proteins from ECF51 are present in Actinobacteria (100%).
Regulation: Even though domains in position +1 are not conserved, proteins in position +1 have homology to AS factors from the original ECF classification (Staroń et al., 2009) (except in subgroup ECF51s4) and contain typically one transmembrane helix (70.73%, ~100% in the MSA). These putative AS factors were also pinpointed in the original ECF51 (Huang et al., 2015). Interestingly, members of ECF51s9 encoded a protein with a σ4 domain (80%) and with the σ2 domain (20%) in -1. These proteins might function as AAS factors since they are transmembrane proteins (100%), their σ2 domain is missing in some cases, and they contain a PknH-like extracellular domain (20%) with sensing functions. Other proteins with σ2 or σ4 domains appear in members of ECF51 with an average of 0.33 per ECF. Although these proteins are usually ECFs from different groups, some are not included in the ECF library and could be AAS factors as in the case of ECF51s9.
Genomic context conservation: Other conserved proteins encoded in the context of ECF51 are only present in ECF51s9 and ECF51s13 and include a CoA-binding protein, a formyltransferase, an AICARFT/IMPCHase bienzyme fused to an MGS-like domain, with potential functions in purine sythesis, and an ATP-grasp-domain protein.
Summary: In conclussion, the AS factors of ECF51, also identified for original ECF51 (Huang et al., 2015), could be regulated, at least in ECF51s9, by partner-switching via AAS that also contain an extracytoplasmic, potentially sensing, domain. The promoter motifs are conserved and agree with original ECF51 (Huang et al., 2015).
Number of representative ECFs: 774
Number of non-redundant ECFs: 761
Sequences with C-terminal extension: 1.84%
Sequences with N-terminal extension: 2.63%
Overrepresented class: Actinobacteria [99.74%]
|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|
|Environmental Sensing in Actinobacteria: a Comprehensive Survey on the Signaling Capacity of This Phylum.||Journal of bacteriology||2015||X. Huang, D. Pinto, G. Fritz, T. Mascher||PubMed: 25986905||ECF122, ECF56, ECF118, ECF128, ECF51, ECF52, ECF132, ECF53, ECF123, ECF125, ECF54, ECF130, ECF131, ECF218, ECF294, ECF48|