SUPERFAMILY 1.75 HMM library and genome assignments server

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SirA-like superfamily

SCOP classification
Root:   SCOP hierarchy in SUPERFAMILY [ 0] (11)
Class:   Alpha and beta proteins (a+b) [ 53931] (376)
Fold:   IF3-like [ 55199] (8)
Superfamily:   SirA-like [ 64307]
Families:   SirA-like [ 88852] (4)

Superfamily statistics
Genomes (1,623) Uniprot 2018_03 genome PDB chains (SCOP 1.75)
Domains 3,053 23,171 4
Proteins 3,051 23,147 4

Functional annotation
General category Regulation
Detailed category Other regulatory function

Function annotation of SCOP domain superfamilies

UniProtKB KeyWords (KW)

(show details) Document: KW annotation of SCOP domains

InterPro annotation
Cross references IPR001455 SSF64307 Protein matches

SirA functions as a response regulator as part of a two-component system, where BarA is the sensor kinase. This system increases the expression of virulence genes and decreases the expression of motility genes [PubMed14645287]. BarA phosphorylates SirA, thereby activating the protein. Phosphorylated SirA directly activates virulence expression by interacting with hilA and hilC promoters, while repressing the flagellar regulon indirectly by binding to the csrB promoter, which in turn affects flagellar gene expression. Orthologues of SirA from Salmonella spp. can be found throughout proteobacteria, such as GacA in Psuedomonas spp., VarA in Vibrio cholerae, ExpA in Erwinia carotovora, LetA in Legionella pneumophila, and UvrY in Escherichia coli [PubMed11768529]. A sensor kinase for SirA is present in each of these organisms as well; the sensor kinase is known as BarA in E. coli and Salmonella spp., but has different names in other genera. In different species, SirA/BarA orthologues are required for virulence gene expression, exoenzyme and antibiotic production, motility, and biofilm formation.

The structure of SirA consists of an alpha/beta sandwich with a beta-alpha-beta-alpha-beta(2) fold, comprising a mixed four-stranded beta-sheet stacked against two alpha-helices, both of which are nearly parallel to the strands of the beta-sheet [PubMed11080457].

Several uncharacterised bacterial proteins (73 to 81 amino-acid residues in length) that contain a well-conserved region in their N-terminal region show structural similarity to the SirA protein, including the E. coli protein YedF, and other members of the UPF0033 family.

InterPro database

PDBeMotif information about ligands, sequence and structure motifs
Cross references PDB entries
Ligand binding statistics
Nucleic-acid binding statistics
Occurrence of secondary structure elements
Occurrence of small 3D structural motifs

PDBeMotif resource

Jump to [ Top of page · SCOP classification · InterPro annotation · PDBeMotif links · Functional annotation · UniProtKB KeyWords (KW) ]

Internal database links

Browse genome assignments for this superfamily. The SUPERFAMILY hidden Markov model library has been used to carry out SCOP domain assignments to all genomes at the superfamily level.

Alignments of sequences to 4 models in this superfamily are available by clicking on the 'Alignments' icon above. PDB sequences less than 40% identical are shown by default, but any other sequence(s) may be aligned. Select PDB sequences, genome sequences, or paste in or upload your own sequences.

Browse and view proteins in genomes which have different domain combinations including a SirA-like domain.

Examine the distribution of domain superfamilies, or families, across the major taxonomic kingdoms or genomes within a kingdom. This gives an immediate impression of how superfamilies, or families, are restricted to certain kingdoms of life.

Explore domain occurrence network where nodes represent genomes and edges are domain architectures (shared between genomes) containing the superfamily of interest.

There are 4 hidden Markov models representing the SirA-like superfamily. Information on how the models are built, and plots showing hydrophobicity, match emmission probabilities and insertion/deletion probabilities can be inspected.

Jump to [ Top of page · SCOP classification · InterPro annotation · PDBeMotif links · Functional annotation · UniProtKB KeyWords (KW) · Internal database links ]