The answer structure of the protein YndB has been solved using NMR in order to investigate proposed biological functions. that preferentially bind YndB. The screen recognized in order of affinity the chalcone/hydroxychalcone flavanone and flavone/flavonol classes of lipids which was further verified by 2D 1H-15N HSQC NMR titration experiments with to chalcone-like flavonoids released by plants PHA-665752 due to a pathogen contamination. The observed binding of chalcone-like molecules by YndB is likely related to the symbiotic relationship between and plants. INTRODUCTION The Bet v 1 protein from birch is usually a major allergen with high sequence similarity to the herb PR-10 pathogenesis-related proteins which are involved in the response of plants towards microbial contamination.1 Since the Bet v 1 protein structure was solved 2 numerous other proteins from among eukaryotes archaea and bacteria have been identified as having the same characteristic fold.3 The Bet v 1-like superfamily of proteins now contains approximately 10 135 sequences and consists of 13 unique families. The four largest families in the Bet v 1-like superfamily are the polyketide cyclases (3 475 sequences) the ring hydroxylases α-string (2 22 sequences) the activator of Hsp90 ATPase homolog 1-like proteins (AHSA1) family members (1 762 sequences) as well as the StAR-related lipid transfer (Begin) family members (1 26 sequences). The series similarity among the various Wager v 1-like households is commonly fairly low (0 to 38%) but all support the same helix-grip fold that forms a hydrophobic cavity among the lengthy C-terminal α-helix as well as the antiparallel β-sheet.3 This hydrophobic cavity provides been proven to bind to lipids sterols polyketide antibiotics and various other hydrophobic substances preferentially.3 As the Bet v 1-like superfamily associates share an identical fold the natural functions vary over the different households. The band hydroxylases degrade polycyclic aromatic hydrocarbons into nonaromatic YndB proteins is a proteins of unknown natural function targeted for structural evaluation with the Northeast Structural Genomics Consortium (NESG; http://www.nesg.org; NESG focus on: SR211). We previously reported the near comprehensive NMR tasks for YndB 15 where in fact the proteins was originally defined as being a person in the Begin15 16 area because of the equivalent helix-grip fold within the framework of two homologous protein and predicated on CATH evaluations.17 The NMR buildings reported for proteins BC4709 (PDB ID: 1xn6) and proteins BH1534 (PDB ID: 1xn5) resulted in their Begin area classification.16 Both of these protein are 64 and 57% homologous to YndB respectively inferring an identical annotation for YndB. Nevertheless the Pfam and SCOP databases possess suggested that YndB BC4709 and BH1534 participate in PHA-665752 the AHSA1 family. Sequence similarity searches with YndB only identify proteins annotated as either AHSA1 or proteins of unknown function. The primary difference between the START domain and AHSA1 Rabbit Polyclonal to PDGFRb. structures is that START domain proteins typically contain two additional N-terminal β-strands and an α-helix which also makes the proteins larger. The structure of BC4709 and BH1534 do not have these additional structural components further supporting the AHSA1 classification. Assigning a function to an uncharacterized protein like YndB can be a daunting task that involves obtaining a high-resolution structure18 combined with detailed studies that may include generating knockout libraries to analyze cell phenotypes monitoring gene expression levels or performing pull-down assays all of which require in-depth bioinformatics analyses.19-23 Since the biological function of a protein is by definition derived from its interactions with other biomolecules or small molecules identifying interacting partners is an alternative route to obtaining a functional annotation. One such technique FAST-NMR 24 25 utilizes a small biologically-focused compound library combined with NMR high-throughput screening (HTS) quick protein-ligand co-structures using AutoDock26 and chemical shift perturbations 27 and a comparison of protein active site structures (CPASS)28 to assist the functional annotation of proteins. However the power of FAST-NMR relies on structural homologs being found within the diverse functional chemical library. In the case of YndB the known Bet v 1-like superfamily ligands combined with the expected hydrophobic cavity for YndB already suggests the protein is. PHA-665752