PDBsum entry 2xd2

Sugar binding protein

PDB id: 2xd2

Contents

Protein chains

379 a.a. *

Waters ×58

* Residue conservation analysis

PDB id:

2xd2

Name:

Sugar binding protein

Title:

The crystal structure of malx from streptococcus pneumoniae

Structure:

Maltose/maltodextrin-binding protein. Chain: a, b. Fragment: residues 31-423. Synonym: malx. Engineered: yes

Source:

Streptococcus pneumoniae. Organism_taxid: 170187. Strain: tigr4. Expressed in: escherichia coli. Expression_system_taxid: 469008.

Resolution:

2.90Å R-factor: 0.219 R-free: 0.274

Authors:

D.W.Abbott,M.A.Higgins,S.Hyrnuik,B.Pluvinage,A.Lammerts Van Bueren, A.B.Boraston

Key ref:

D.W.Abbott et al. (2010). The molecular basis of glycogen breakdown and transport in Streptococcus pneumoniae. Mol Microbiol, 77, 183-199. PubMed id: 20497336

Date:

28-Apr-10 Release date: 09-Jun-10

Protein chains

P59213  (MALX_STRPN) -  Maltooligosaccharide ABC transporter solute-binding lipoprotein from Streptococcus pneumoniae serotype 4 (strain ATCC BAA-334 / TIGR4)

Seq: 423 a.a.

Struc: 379 a.a.*

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.?

Mol Microbiol 77:183-199 (2010)

PubMed id: 20497336

The molecular basis of glycogen breakdown and transport in Streptococcus pneumoniae.

D.W.Abbott, M.A.Higgins, S.Hyrnuik, B.Pluvinage, A.Lammerts van Bueren, A.B.Boraston.

ABSTRACT

SUMMARY The genome of Streptococcus pneumoniae strains, as typified by the TIGR4 strain, contains several genes encoding proteins putatively involved in alpha-glucan degradation, modification and synthesis. The extracellular components comprise an ABC-transporter with its solute-binding protein, MalX, and the hydrolytic enzyme SpuA. We show that of the commonly occurring exogenous alpha-glucans, S. pneumoniae TIGR4 is only able to grow on glycogen in a MalX and SpuA-dependent manner. SpuA is able to degrade glycogen into a ladder of alpha-1,4-glucooligosaccharides while the high affinity interaction (K(a) approximately 10(6) M(-1)) of MalX with maltooligosaccharides plays a key role in promoting the selective uptake of the glycogen degradation products that are produced by SpuA. The X-ray crystallographic analyses of apo- and complexed MalX illuminate the protein's specificity for the degradation products of glycogen and its striking ability to recognize the helical structure of the ligand. Overall, the results of this work provide new structural and functional insight into streptococcal alpha-glucan metabolism while supplying biochemical support for the hypothesis that the substrate of the S. pneumoniaealpha-glucan metabolizing machinery is glycogen, which in a human host is abundant in lung epithelial cells, a common target for invasive S. pneumoniae.