Structure-function relationships in the MppP family
Mentor 1
Nicholas Silvaggi
Start Date
1-5-2020 12:00 AM
Description
The rare nonproteinogenic amino acid L-enduracididine (L-End) is a building block of some naturally occurring antibiotics like mannopeptimycin. Antibiotic-resistant pathogens are an imminent threat to public health. Studying the biosynthetic pathways by which natural antibiotics are formed by bacteria and fungi can provide valuable information for drug design. L-End biosynthesis involves one particularly interesting enzyme, a pyridoxal-5’phosphate (PLP) dependent L-Arg oxidase, called MppP. MppP is unique in that it is the first PLP-dependent enzyme to perform a 4-electron oxidation with just molecular oxygen and PLP. This is highly unusual in that this sort of chemistry typically uses metals or more exotic organic cofactors. A number of MppP homologs have been identified and this small family actually contains two different groups. One catalyzes the reaction that results in the hydroxylated arginine product, while the other has a fundamentally different reaction mechanism that results in the product 4,5-dehydro-2-ketoarginine. Our studies aim to identify the structural differences between these two groups of enzymes that result in their having different catalytic mechanisms. So far, the active sites of these homologs seem to have completely conserved amino acid sequences and thus likely very similar structures. Here we describe the first complete structure of a dehydrating MppP homolog from Pseudoalteromonas luteoviolacea (PlMppP). This structure is compared to the prototypical hydroxylating MppP from Streptomyces wadayamensis (SwMppP). We also report on the expression and purification of several other dehydrating MppP homologs, the structures of which will eventually allow us to refine and extend our analysis. The structural data we are generating will have implications for adapting MppP-like enzymes to be used as biocatalysts for the synthesis of potentially novel life-saving antibiotics.
Structure-function relationships in the MppP family
The rare nonproteinogenic amino acid L-enduracididine (L-End) is a building block of some naturally occurring antibiotics like mannopeptimycin. Antibiotic-resistant pathogens are an imminent threat to public health. Studying the biosynthetic pathways by which natural antibiotics are formed by bacteria and fungi can provide valuable information for drug design. L-End biosynthesis involves one particularly interesting enzyme, a pyridoxal-5’phosphate (PLP) dependent L-Arg oxidase, called MppP. MppP is unique in that it is the first PLP-dependent enzyme to perform a 4-electron oxidation with just molecular oxygen and PLP. This is highly unusual in that this sort of chemistry typically uses metals or more exotic organic cofactors. A number of MppP homologs have been identified and this small family actually contains two different groups. One catalyzes the reaction that results in the hydroxylated arginine product, while the other has a fundamentally different reaction mechanism that results in the product 4,5-dehydro-2-ketoarginine. Our studies aim to identify the structural differences between these two groups of enzymes that result in their having different catalytic mechanisms. So far, the active sites of these homologs seem to have completely conserved amino acid sequences and thus likely very similar structures. Here we describe the first complete structure of a dehydrating MppP homolog from Pseudoalteromonas luteoviolacea (PlMppP). This structure is compared to the prototypical hydroxylating MppP from Streptomyces wadayamensis (SwMppP). We also report on the expression and purification of several other dehydrating MppP homologs, the structures of which will eventually allow us to refine and extend our analysis. The structural data we are generating will have implications for adapting MppP-like enzymes to be used as biocatalysts for the synthesis of potentially novel life-saving antibiotics.
