6x3k

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Hsa Siglec and Unique domains in complex with 6S-sialy-Lewisx

Structural highlights

6x3k is a 1 chain structure with sequence from Streptococcus gordonii str. Challis. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 2.5Å
Ligands:	, , , ,
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

HSA_STRGC A cell wall protein involved with PadA in host cell interactions required for colonization and pathogensis (Probable) (PubMed:19884334, PubMed:27616700). Mediates hemagglutination and adherence to ghst glycoproteins (PubMed:11854202). Recognizes fetuin-A (AHSG), a highly glycosylated human plasma protein, also involved in recognition of human platelets, probably via platelet glycoprotein Ib alpha (GP1BA) (PubMed:19884334). Acts in concert with PadA to promote binding to glycosylated human fibronectin (FN1) and vitronectin (VTN), and biofilm formation. Plays a major role in fibronectin and vitronectin binding; binding is mediated by glycosylated regions. Probably mediates interaction of PadA with resting platelets (PubMed:27616700).^[1] ^[2] ^[3] ^[4]

Publication Abstract from PubMed

Bacterial binding to host receptors underlies both commensalism and pathogenesis. Many streptococci adhere to protein-attached carbohydrates expressed on cell surfaces using Siglec-like binding regions (SLBRs). The precise glycan repertoire recognized may dictate whether the organism is a strict commensal versus a pathogen. However, it is currently not clear what drives receptor selectivity. Here, we use five representative SLBRs and identify regions of the receptor binding site that are hypervariable in sequence and structure. We show that these regions control the identity of the preferred carbohydrate ligand using chimeragenesis and single amino acid substitutions. We further evaluate how the identity of the preferred ligand affects the interaction with glycoprotein receptors in human saliva and plasma samples. As point mutations can change the preferred human receptor, these studies suggest how streptococci may adapt to changes in the environmental glycan repertoire.

Origins of glycan selectivity in streptococcal Siglec-like adhesins suggest mechanisms of receptor adaptation.,Bensing BA, Stubbs HE, Agarwal R, Yamakawa I, Luong K, Solakyildirim K, Yu H, Hadadianpour A, Castro MA, Fialkowski KP, Morrison KM, Wawrzak Z, Chen X, Lebrilla CB, Baudry J, Smith JC, Sullam PM, Iverson TM Nat Commun. 2022 May 18;13(1):2753. doi: 10.1038/s41467-022-30509-y. PMID:35585145^[5]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Takahashi Y, Konishi K, Cisar JO, Yoshikawa M. Identification and characterization of hsa, the gene encoding the sialic acid-binding adhesin of Streptococcus gordonii DL1. Infect Immun. 2002 Mar;70(3):1209-18. PMID:11854202 doi:10.1128/IAI.70.3.1209-1218.2002
↑ Petersen HJ, Keane C, Jenkinson HF, Vickerman MM, Jesionowski A, Waterhouse JC, Cox D, Kerrigan SW. Human platelets recognize a novel surface protein, PadA, on Streptococcus gordonii through a unique interaction involving fibrinogen receptor GPIIbIIIa. Infect Immun. 2010 Jan;78(1):413-22. PMID:19884334 doi:10.1128/IAI.00664-09
↑ Haworth JA, Jenkinson HF, Petersen HJ, Back CR, Brittan JL, Kerrigan SW, Nobbs AH. Concerted functions of Streptococcus gordonii surface proteins PadA and Hsa mediate activation of human platelets and interactions with extracellular matrix. Cell Microbiol. 2017 Jan;19(1):e12667. PMID:27616700 doi:10.1111/cmi.12667
↑ Takahashi Y, Konishi K, Cisar JO, Yoshikawa M. Identification and characterization of hsa, the gene encoding the sialic acid-binding adhesin of Streptococcus gordonii DL1. Infect Immun. 2002 Mar;70(3):1209-18. PMID:11854202 doi:10.1128/IAI.70.3.1209-1218.2002
↑ Bensing BA, Stubbs HE, Agarwal R, Yamakawa I, Luong K, Solakyildirim K, Yu H, Hadadianpour A, Castro MA, Fialkowski KP, Morrison KM, Wawrzak Z, Chen X, Lebrilla CB, Baudry J, Smith JC, Sullam PM, Iverson TM. Origins of glycan selectivity in streptococcal Siglec-like adhesins suggest mechanisms of receptor adaptation. Nat Commun. 2022 May 18;13(1):2753. PMID:35585145 doi:10.1038/s41467-022-30509-y