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43  structures 39  species 0  interactions 53  sequences 43  architectures

Family: SdrG_C_C (PF10425)

Summary: C-terminus of bacterial fibrinogen-binding adhesin

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This is the Wikipedia entry entitled "SdrG C terminal protein domain". More...

SdrG C terminal protein domain Edit Wikipedia article

SdrG, C-terminal domain
PDB 1r17 EBI.jpg
Crystal structure analysis of S.epidermidis adhesin SdrG binding to fibrinogen (adhesin-ligand complex)

In molecular biology, the protein domain SdrG C terminal refers to the C terminus domain of an adhesin found only on the cell walls of bacteria. More specifically, SdrG is only found in gram-positive bacteria. This particular domain binds to a glycoprotein named fibrinogen. SdrG stands for serine-aspartate dipeptide repeats, which as its name suggests, contains repeats of two amino acids, serine and aspartate.[1]

Gram-positive pathogens such as Staphylococci, Streptococci, and Enterococci, contain SdrG anchored to their cell walls; these proteins act as adhesins and help the bacteria adhere to the host tissues via a dock-lock-latch mechanism.[2] This protein domain is of huge significance since it binds to fibrinogen, a glycoprotein involved in important processes such as haemostasis and coagulation.[3] By understanding more about the way they attach to human cells, it is hope a therapeutic target can be developed to preven diseases such as nosocomial sepsis[2] which are caused by a bacterium which operates in this manner.


SdrG protein function

SdrG protein is a bacterial cell wall-anchored adhesion and its function is to adhere to human cells. It does this by binding to the Beta chain of human fibrinogen which is found in the extracellular matrix. Such adhesins have also been named MSCRAMMs which is short for microbial surface components recognizing adhesive matrix molecules.[2]

SdrG C-terminal domain function

The C-terminal domain is responsible for the attachment of the protein to the attachment of the protein to the cell wall.[1]


SdrG binds to its ligand with a dynamic "dock, lock, SdrG, the ligand binding site has been further localized and latch" mechanism.[2] When it does bind to fibrinogen, it binds and forms an immunoglobin fold. SdrG as an apoprotein and in complex ligand binding activity peptide analogous to its binding site in Fg.[2]


The whole SdrG protein contains two domains, a N-terminal one named N2 domain and the C-terminal one named N3.[2]

C terminal domain structure

The C terminus contain a LPXTG sequence motif and hydrophobic amino acid segments attached to peptidoglycan.[1] The C-terminal domain has many features which are required to fulfill its role: a proline-rich wall-spanning region, the wall-anchoring LPTXG motif, a hydrophobic transmembrane region and a cytoplasmic tail of positively charged amino acid residues.[4] wo main beta sheets made up of four beta strands each arranged in to a beta-sandwich topology. The C-terminal part of SdrG(276-596) is integral to the folding of the immunoglobulin-like whole to create the docking grooves necessary for Fg binding.[2]

Examples of proteins containing the SdrG C terminal domain

  • clumping factor A[4]
  • fibronectin-binding proteins A and B[4]


  1. ^ a b c McCrea KW, Hartford O, Davis S, Eidhin DN, Lina G, Speziale P, et al. (2000). "The serine-aspartate repeat (Sdr) protein family in Staphylococcus epidermidis". Microbiology. 146 (7): 1535–46. doi:10.1099/00221287-146-7-1535. PMID 10878118.
  2. ^ a b c d e f g Ponnuraj K, Bowden MG, Davis S, Gurusiddappa S, Moore D, Choe D, et al. (2003). "A "dock, lock, and latch" structural model for a staphylococcal adhesin binding to fibrinogen". Cell. 115 (2): 217–28. doi:10.1016/S0092-8674(03)00809-2. PMID 14567919.
  3. ^ Davis SL; Gurusiddappa S; McCrea KW; Perkins S; Höök M (2001). "SdrG, a fibrinogen-binding bacterial adhesin of the microbial surface components recognizing adhesive matrix molecules subfamily from Staphylococcus epidermidis, targets the thrombin cleavage site in the Bbeta chain". J Biol Chem. 276 (30): 27799–805. doi:10.1074/jbc.M103873200. PMID 11371571.
  4. ^ a b c Deivanayagam CC, Wann ER, Chen W, Carson M, Rajashankar KR, Höök M, et al. (2002). "A novel variant of the immunoglobulin fold in surface adhesins of Staphylococcus aureus: crystal structure of the fibrinogen-binding MSCRAMM, clumping factor A." EMBO J. 21 (24): 6660–72. doi:10.1093/emboj/cdf619. PMC 139082. PMID 12485987.
This article incorporates text from the public domain Pfam and InterPro: IPR011266

This page is based on a Wikipedia article. The text is available under the Creative Commons Attribution/Share-Alike License.

This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.

C-terminus of bacterial fibrinogen-binding adhesin Provide feedback

This is the C-terminal half of a bacterial fibrinogen-binding adhesin SdrG. SdrG is a Gram-positive cell-wall-anchored adhesin that allows attachment of the bacterium to host tissues via specific binding to the beta-chain of human fibrinogen (Fg). SdrG binds to its ligand with a dynamic "dock, lock, and latch" mechanism which represents a general mode of ligand-binding for structurally related cell wall-anchored proteins in most Gram-positive bacteria. The C-terminal part of SdrG(276-596) is integral to the folding of the immunoglobulin-like whole to create the docking grooves necessary for Fg binding. The domain is associated with families of Cna_B, PF05738 [1].

Literature references

  1. Ponnuraj K, Bowden MG, Davis S, Gurusiddappa S, Moore D, Choe D, Xu Y, Hook M, Narayana SV; , Cell. 2003;115:217-228.: A "dock, lock, and latch" structural model for a staphylococcal adhesin binding to fibrinogen. PUBMED:14567919 EPMC:14567919

This tab holds annotation information from the InterPro database.

InterPro entry IPR011266

This entry represents the fibrinogen-binding domain from bacterial proteins such as fibrinogen-binding adhesion SdrG and clumping factor A. In both SdrG and clumping factor A, there are two fibrinogen-binding domains with similar core beta-sandwich topologies, but with different modulations in their structure. This entry represents the second domain, while INTERPRO represents the first domain.

Gram-positive pathogens, such as Staphylococci, Streptococci, and Enterococci, contain multiple cell wall-anchored proteins. Some of these proteins act as adhesins and mediate bacterial attachment to host tissues through lock-and-interactions with host ligands, such as fibrinogen, a glycoprotein found in blood plasma that plays a key role in haemostasis and coagulation. For pathogenic bacteria that do not invade host cells, extracellular matrix proteins are preferred targets for bacterial adhesion; adhesins mediating these interactions have been termed MSCRAMMs (microbial surface components recognizing adhesive matrix molecules). A common binding domain organisation found within MSCRAMMs suggests a common ancestry. Both fibrinogen-binding adhesion SdrG and clumping factor A are MSCRAMMs.

Gene Ontology

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Domain organisation

Below is a listing of the unique domain organisations or architectures in which this domain is found. More...

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Pfam Clan

This family is a member of clan Adhesin (CL0204), which has the following description:

This superfamily includes a variety of bacterial adhesins that have a jelly-roll beta-barrel fold [1]. These domains are involved in sugar recognition.

The clan contains the following 13 members:

Adhesin_Dr AfaD Antig_Caf1 Collagen_bind DUF1120 Fim-adh_lectin FimA Fimbrial FimH_man-bind PapG_N Saf-Nte_pilin SCPU SdrG_C_C


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Curation and family details

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Seed source: Gene3D, pdb_1r17
Previous IDs: none
Type: Domain
Sequence Ontology: SO:0000417
Author: Finn RD , Coggill P
Number in seed: 10
Number in full: 53
Average length of the domain: 152.60 aa
Average identity of full alignment: 18 %
Average coverage of the sequence by the domain: 10.14 %

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HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 57096847 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 24.4 24.4
Trusted cut-off 25.8 24.7
Noise cut-off 24.1 23.0
Model length: 156
Family (HMM) version: 11
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Species distribution

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Archea Archea Eukaryota Eukaryota
Bacteria Bacteria Other sequences Other sequences
Viruses Viruses Unclassified Unclassified
Viroids Viroids Unclassified sequence Unclassified sequence


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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the SdrG_C_C domain has been found. There are 43 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein sequence.

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AlphaFold Structure Predictions

The list of proteins below match this family and have AlphaFold predicted structures. Click on the protein accession to view the predicted structure.

Protein Predicted structure External Information
P14738 View 3D Structure Click here
Q2FUY2 View 3D Structure Click here
Q2G015 View 3D Structure Click here
Q2G0L4 View 3D Structure Click here
Q2G0L5 View 3D Structure Click here
Q2G1T5 View 3D Structure Click here