2aac

From Proteopedia

ESCHERCHIA COLI GENE REGULATORY PROTEIN ARAC COMPLEXED WITH D-FUCOSE

Structural highlights

2aac is a 2 chain structure with sequence from Escherichia coli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 1.6Å
Ligands:	,
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

ARAC_ECOLI This protein controls the expression of at least six genes that are involved in the transport and catabolism of L-arabinose. It regulates initiation of transcription of the araBAD operon and it also controls its own synthesis. The L-arabinose operon displays both positive and negative regulation through AraC.

Evolutionary Conservation

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

Publication Abstract from PubMed

The crystal structure of the sugar-binding and dimerization domain of the Escherichia coli gene regulatory protein, AraC, has been determined in complex with the competitive inhibitor D-fucose at pH 5.5 to a resolution of 1.6 A. An in-depth analysis shows that the structural basis for AraC carbohydrate specificity arises from the precise arrangement of hydrogen bond-forming protein side-chains around the bound sugar molecule. van der Waals interactions also contribute to the epimeric and anomeric selectivity of the protein. The methyl group of D-fucose is accommodated by small side-chain movements in the sugar-binding site that result in a slight distortion in the positioning of the amino-terminal arm. A comparison of this structure with the 1.5 A structure of AraC complexed with L-arabinose at neutral pH surprisingly revealed very small structural changes between the two complexes. Based on solution data, we suspect that the low pH used to crystallize the fucose complex affected the structure, and speculate about the nature of the changes between pH 5.5 and neutral pH and their implications for gene regulation by AraC. A comparison with the structurally unrelated E. coli periplasmic sugar-binding proteins reveals that conserved features of carbohydrate recognition are present, despite a complete lack of structural similarity between the two classes of proteins, suggesting convergent evolution of carbohydrate binding.

The 1.6 A crystal structure of the AraC sugar-binding and dimerization domain complexed with D-fucose.,Soisson SM, MacDougall-Shackleton B, Schleif R, Wolberger C J Mol Biol. 1997 Oct 17;273(1):226-37. PMID:9367758^[1]

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

References

↑ Soisson SM, MacDougall-Shackleton B, Schleif R, Wolberger C. The 1.6 A crystal structure of the AraC sugar-binding and dimerization domain complexed with D-fucose. J Mol Biol. 1997 Oct 17;273(1):226-37. PMID:9367758 doi:10.1006/jmbi.1997.1314