Arylformamidase Introduction

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why it was chosen for structural determination

The structure was determined using X-ray diffraction by the Joint Center for Structural Genomics (JCSG) (see figure 2). The organism is Silicibacter SP. TM1040 and the protein expression system is Escherichia Coli using a plasmid as the vector. A resolution of 1.79 A was achieved with an R-value of 0.224 and an R-free value of 0.270. The closer the R values are to each other, the better the quality of the structure.

Figure 2: An overview of 2pbl exhibiting all chains. The image above shows the chains A (upper right), B (upper left), C (lower right) & D (lower left) interacting. The red molecule in the chain structure is an unknown ligand. The molecules in the middle of chains A & B and chains C & D is phosphate ion (PO4). The green molecule between chain B & D is a magnesium ion (Mg). Image generated using PDB ProteinWorkshop 1.5.

Upon crystallisation, 2pbl formed a tetramer structure. However, structures formed upon crystalisation do not always denote the functional form of a protein which can exist as a dimer or oligomer as well. In fact, such forms may have been evolutionary selected for to confer features such as thermostability (Byun 2007). By examining the crystal structure and … , we have attempted to deduce the functional form of 2pbl.

'Arylformamidase' heralds from Silibacter sp. TM1040, a member of the Roseobacter clade of alpha-proteobacteria. It was first isolated as part of an investigation into the role of bacteria in the physiology and toxigenesis of the dinoflagellate Pfiestera piscicida. Silicibacter sp. TM1040 has been found necessary for the survival of this organism. Most interestingly, the bacteria is able to demethylate the dinoflagellate secondary metabolite dimethylsulfoniopropionate (DMSP) to methylmercaptopropionic acid (MMPA). DMSP is the major source of organic sulphur in the world’s oceans, forming a major part of the global sulphur cycle.


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