1g5q: Difference between revisions

[[Image:1g5q.jpg|left|200px]]<br /><applet load="1g5q" size="350" color="white" frame="true" align="right" spinBox="true"  

Epidermin from Staphylococcus epidermidis Tu3298 is an antimicrobial peptide of the lantibiotic family that contains, amongst other unusual amino acids, S:-[(Z:)- 2-aminovinyl]-D-cysteine. This residue is introduced by post-translational modification of the ribosomally synthesized precursor EpiA. Modification starts with the oxidative decarboxylation of its C-terminal cysteine by the flavoprotein EpiD generating a reactive (Z:)-enethiol intermediate. We have determined the crystal structures of EpiD and EpiD H67N in complex with the substrate pentapeptide DSYTC at 2.5 A resolution. Rossmann-type monomers build up a dodecamer of 23 point symmetry with trimers disposed at the vertices of a tetrahedron. Oligomer formation is essential for binding of flavin mononucleotide and substrate, which is buried by an otherwise disordered substrate recognition clamp. A pocket for the tyrosine residue of the substrate peptide is formed by an induced fit mechanism. The substrate contacts flavin mononucleotide only via Cys-Sgamma, suggesting its oxidation as the initial step. A thioaldehyde intermediate could undergo spontaneous decarboxylation. The unusual substrate recognition mode and the type of chemical reaction performed provide insight into a novel family of flavoproteins.

1G5Q is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Staphylococcus_epidermidis Staphylococcus epidermidis] with <scene name='pdbligand=FMN:'>FMN</scene> and <scene name='pdbligand=TRS:'>TRS</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1G5Q OCA].  

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