AgrD

Staphylococcal AgrD protein

• SMART accession number: SM00794
• Description: This family consists of several AgrD proteins from many Staphylococcus species. The agr locus was initially described in Staphylococcus aureus as an element controlling the production of exoproteins implicated in virulence. Its pattern of action has been shown to be complex, upregulating certain extracellular toxins and enzymes expressed post-exponentially and repressing some exponential-phase surface components. AgrD encodes the precursor of the autoinducing peptide (AIP).The AIP derived from AgrD by the action of AgrB interacts with AgrC in the membrane to activate AgrA, which upregulates transcription both from promoter P2, amplifying the response, and from P3, initiating the production of a novel effector: RNAIII. In S. aureus, delta-hemolysin is the only translation product of RNA III and is not involved in the regulatory functions of the transcript, which is therefore the primary agent for modulating the expression of other operons controlled by agr (PUBMED:11807079).
• Interpro abstract (IPR009229):

  The agr locus was initially described in Staphylococcus aureus as an element controlling the production of exoproteins implicated in virulence. Its pattern of action has been shown to be complex, upregulating certain extracellular toxins and enzymes expressed post-exponentially and repressing some exponential-phase surface components. AgrD encodes the precursor of the autoinducing peptide (AIP).The AIP derived from AgrD by the action of AgrB interacts with AgrC in the membrane to activate AgrA, which upregulates transcription both from promoter P2, amplifying the response, and from P3, initiating the production of a novel effector: RNAIII. In S. aureus, delta-hemolysin is the only translation product of RNA III and is not involved in the regulatory functions of the transcript, which is therefore the primary agent for modulating the expression of other operons controlled by agr [ (PUBMED:11807079) ].

  Members of this family of short peptides are precursors to thiolactone (unless Cys is replaced by Ser) cyclic autoinducer peptides, used in quorum-sensing systems in Gram-positive bacteria. The best characterised is the AgrD precursor, processed by the AgrB protein. Nearby proteins regularly encountered include a histidine kinase and a response regulator.

There are 76 AgrD domains in 76 proteins in SMART's nrdb database.

Cellular role (predicted cellular role)

Cellular role: interaction

Literature (relevant references for this domain)

Primary literature is listed below; Automatically-derived, secondary literature is also avaliable.

• Dufour P et al.
• High genetic variability of the agr locus in Staphylococcus species.
• J Bacteriol. 2002; 184: 1180-6

The agr quorum-sensing and signal transduction system was initially described in Staphylococcus aureus, where four distinct allelic variants have been sequenced. Western blotting suggests the presence of homologous loci in many other staphylococci, and this has been confirmed for S. epidermidis and S. lugdunensis. In this study we isolated agr-like loci from a range of staphylococci by using PCR amplification from primers common to the six published agr sequences and bracketing the most variable region, associated with quorum-sensing specificity. Positive amplifications were obtained from 14 of 34 staphylococcal species or subspecies tested. Sequences of the amplicons identified 24 distinct variants which exhibited extensive sequence divergence with only 10% of the nucleotides absolutely conserved on multiple alignment. This variability involved all three open reading frames involved in quorum sensing and signal transduction. However, these variants retained several protein signatures, including the conserved cysteine residue of the autoinducing peptide, with the exception of S. intermedius of pigeon origin, which contained a serine in place of cysteine at this position. We discuss hypotheses on the mode of action and the molecular evolution of the agr locus based on comparisons between the newly determined sequences.

Metabolism (metabolic pathways involving proteins which contain this domain)

% proteins involved	KEGG pathway ID	Description
100.00	map02020	Two-component system - General

This information is based on mapping of SMART genomic protein database to KEGG orthologous groups. Percentage points are related to the number of proteins with AgrD domain which could be assigned to a KEGG orthologous group, and not all proteins containing AgrD domain. Please note that proteins can be included in multiple pathways, ie. the numbers above will not always add up to 100%.

Links (links to other resources describing this domain)

• PFAM: AgrD
• INTERPRO: IPR009229