PMID- 16445940
OWN - NLM
STAT- MEDLINE
DCOM- 20060425
LR  - 20171213
IS  - 0022-2836 (Print)
IS  - 0022-2836 (Linking)
VI  - 357
IP  - 2
DP  - 2006 Mar 24
TI  - Molecular determinants for substrate specificity of the ligand-binding protein 
      OpuAC from Bacillus subtilis for the compatible solutes glycine betaine and 
      proline betaine.
PG  - 592-606
AB  - Compatible solutes play a decisive role in the defense of microorganisms against 
      changes in temperature and increases in osmolarity in their natural habitats. In 
      Bacillus subtilis, the substrate-binding protein (SBP)-dependent ABC-transporter 
      OpuA serves for the uptake of the compatible solutes glycine betaine (GB) and 
      proline betaine (PB). Here, we report the determinants of compatible solute 
      binding by OpuAC, the SBP of the OpuA transporter, by equilibrium binding studies 
      and X-ray crystallography. The affinity of OpuAC/GB and OpuAC/PB complexes were 
      analyzed by intrinsic tryptophan fluorescence and the K(D) values were determined 
      to be 17(+/-1)microM for GB and 295(+/-27)microM for PB, respectively. The 
      structures of OpuAC in complex with GB or PB were solved at 2.0 A and 2.8 A, 
      respectively, and show an SBP-typical class II fold. The ligand-binding pocket is 
      formed by three tryptophan residues arranged in a prism-like geometry suitable to 
      coordinate the positive charge of the trimethyl ammonium group of GB and the 
      dimethyl ammonium group of PB by cation-pi interactions and by hydrogen bonds 
      with the carboxylate moiety of the ligand. Structural differences between the 
      OpuAC/GB and OpuAC/PB complexes occur within the ligand-binding pocket as well as 
      across the domain-domain interface. These differences provide a structural 
      framework to explain the drastic differences in affinity of the OpuAC/GB and 
      OpuAC/PB complexes. A sequence comparison with putative SBP specific for 
      compatible solutes reveals the presence of three distinct families for which the 
      crystal structure of OpuAC might serve as a suitable template to predict the 
      structures of these putative compatible solute-binding proteins.
FAU - Horn, Carsten
AU  - Horn C
AD  - Institute of Biochemistry, Heinrich Heine University Duesseldorf, 
      Universitaetsstr. 1, 40225 Duesseldorf, Germany.
FAU - Sohn-Bosser, Linda
AU  - Sohn-Bosser L
FAU - Breed, Jason
AU  - Breed J
FAU - Welte, Wolfram
AU  - Welte W
FAU - Schmitt, Lutz
AU  - Schmitt L
FAU - Bremer, Erhard
AU  - Bremer E
LA  - eng
SI  - PDB/2B4L
SI  - PDB/2B4M
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20060113
PL  - Netherlands
TA  - J Mol Biol
JT  - Journal of molecular biology
JID - 2985088R
RN  - 0 (ATP-Binding Cassette Transporters)
RN  - 0 (Bacterial Proteins)
RN  - 0 (Escherichia coli Proteins)
RN  - 0 (Lipoproteins)
RN  - 0 (OpuAC protein, Bacillus subtilis)
RN  - 3SCV180C9W (Betaine)
RN  - 9DLQ4CIU6V (Proline)
RN  - S1L688345C (stachydrine)
SB  - IM
MH  - ATP-Binding Cassette Transporters/*chemistry/genetics/*metabolism
MH  - Amino Acid Sequence
MH  - Bacillus subtilis/chemistry
MH  - Bacterial Proteins/*chemistry/genetics/*metabolism
MH  - Betaine/*chemistry/metabolism
MH  - Binding Sites
MH  - Crystallography, X-Ray
MH  - Escherichia coli Proteins/chemistry/genetics
MH  - Lipoproteins/*chemistry/genetics/*metabolism
MH  - Models, Molecular
MH  - Molecular Sequence Data
MH  - Proline/*analogs & derivatives/chemistry/metabolism
MH  - Protein Binding
MH  - *Protein Structure, Tertiary
MH  - Sequence Alignment
MH  - Substrate Specificity
EDAT- 2006/02/01 09:00
MHDA- 2006/04/28 09:00
CRDT- 2006/02/01 09:00
PHST- 2005/09/27 00:00 [received]
PHST- 2005/12/22 00:00 [revised]
PHST- 2005/12/29 00:00 [accepted]
PHST- 2006/02/01 09:00 [pubmed]
PHST- 2006/04/28 09:00 [medline]
PHST- 2006/02/01 09:00 [entrez]
AID - S0022-2836(05)01675-X [pii]
AID - 10.1016/j.jmb.2005.12.085 [doi]
PST - ppublish
SO  - J Mol Biol. 2006 Mar 24;357(2):592-606. doi: 10.1016/j.jmb.2005.12.085. Epub 2006 
      Jan 13.