PDBsum entry 3k8l

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protein ligands metals Protein-protein interface(s) links
Membrane protein PDB id
Protein chains
649 a.a. *
CEX ×2
CEY ×3
EDO ×4
_CA ×4
Waters ×538
* Residue conservation analysis
PDB id:
Name: Membrane protein
Title: Crystal structure of susg-d498n mutant with maltoheptaose
Structure: Alpha-amylase, susg. Chain: a, b. Engineered: yes. Mutation: yes
Source: Bacteroides thetaiotaomicron. Organism_taxid: 818. Strain: vpi-5482. Gene: bt_3698, susg. Expressed in: escherichia coli. Expression_system_taxid: 562.
2.30Å     R-factor:   0.184     R-free:   0.216
Authors: N.M.Koropatkin,T.J.Smith
Key ref: N.M.Koropatkin and T.J.Smith (2010). SusG: a unique cell-membrane-associated alpha-amylase from a prominent human gut symbiont targets complex starch molecules. Structure, 18, 200-215. PubMed id: 20159465
14-Oct-09     Release date:   02-Mar-10    
Go to PROCHECK summary

Protein chains
Pfam   ArchSchema ?
Q8A1G3  (Q8A1G3_BACTN) -  Alpha-amylase SusG
692 a.a.
649 a.a.*
Key:    PfamA domain  Secondary structure  CATH domain
* PDB and UniProt seqs differ at 1 residue position (black cross)

 Enzyme reactions 
   Enzyme class: E.C.  - Alpha-amylase.
[IntEnz]   [ExPASy]   [KEGG]   [BRENDA]
      Reaction: Endohydrolysis of 1,4-alpha-glucosidic linkages in oligosaccharides and polysaccharides.
 Gene Ontology (GO) functional annotation 
  GO annot!
  Cellular component     membrane   3 terms 
  Biological process     metabolic process   4 terms 
  Biochemical function     catalytic activity     9 terms  


Structure 18:200-215 (2010)
PubMed id: 20159465  
SusG: a unique cell-membrane-associated alpha-amylase from a prominent human gut symbiont targets complex starch molecules.
N.M.Koropatkin, T.J.Smith.
SusG is an alpha-amylase and part of a large protein complex on the outer surface of the bacterial cell and plays a major role in carbohydrate acquisition by the animal gut microbiota. Presented here, the atomic structure of SusG has an unusual extended, bilobed structure composed of amylase at one end and an unprecedented internal carbohydrate-binding motif at the other. Structural studies further demonstrate that the carbohydrate-binding motif binds maltooligosaccharide distal to, and on the opposite side of, the amylase catalytic site. SusG has an additional starch-binding site on the amylase domain immediately adjacent to the active cleft. Mutagenesis analysis demonstrates that these two additional starch-binding sites appear to play a role in catabolism of insoluble starch. However, elimination of these sites has only a limited effect, suggesting that they may have a more important role in product exchange with other Sus components.

Literature references that cite this PDB file's key reference

  PubMed id Reference
21219452 D.Dodd, R.I.Mackie, and I.K.Cann (2011).
Xylan degradation, a metabolic property shared by rumen and human colonic Bacteroidetes.
  Mol Microbiol, 79, 292-304.  
  20944222 C.Bakolitsa, Q.Xu, C.L.Rife, P.Abdubek, T.Astakhova, H.L.Axelrod, D.Carlton, C.Chen, H.J.Chiu, T.Clayton, D.Das, M.C.Deller, L.Duan, K.Ellrott, C.L.Farr, J.Feuerhelm, J.C.Grant, A.Grzechnik, G.W.Han, L.Jaroszewski, K.K.Jin, H.E.Klock, M.W.Knuth, P.Kozbial, S.S.Krishna, A.Kumar, W.W.Lam, D.Marciano, D.McMullan, M.D.Miller, A.T.Morse, E.Nigoghossian, A.Nopakun, L.Okach, C.Puckett, R.Reyes, H.J.Tien, C.B.Trame, H.van den Bedem, D.Weekes, K.O.Hodgson, J.Wooley, M.A.Elsliger, A.M.Deacon, A.Godzik, S.A.Lesley, and I.A.Wilson (2010).
Structure of BT_3984, a member of the SusD/RagB family of nutrient-binding molecules.
  Acta Crystallogr Sect F Struct Biol Cryst Commun, 66, 1274-1280.
PDB code: 3cgh
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