The Vitamin B1 Metabolism of Staphylococcus aureus Is Controlled at Enzymatic and Transcriptional Levels

Ingrid B Müller,Carsten Wrenger,Leonard Amaral,Isabel Couto,Rolf D Walter,Matthew R Groves,Bärbel Bergmann,Tadhg P Begley,Frank R Deleo

doi:10.1371/journal.pone.0007656

Abstract

Vitamin B1 is in its active form thiamine pyrophosphate (TPP), an essential cofactor for several key enzymes in the carbohydrate metabolism. Mammals must salvage this crucial nutrient from their diet in order to complement the deficiency of de novo synthesis. In the human pathogenic bacterium Staphylococcus aureus, two operons were identified which are involved in vitamin B1 metabolism. The first operon encodes for the thiaminase type II (TenA), 4-amino-5-hydroxymethyl-2-methylpyrimidine kinase (ThiD), 5-(2-hydroxyethyl)-4-methylthiazole kinase (ThiM) and thiamine phosphate synthase (ThiE). The second operon encodes a phosphatase, an epimerase and the thiamine pyrophosphokinase (TPK). The open reading frames of the individual operons were cloned, their corresponding proteins were recombinantly expressed and biochemically analysed. The kinetic properties of the enzymes as well as the binding of TPP to the in vitro transcribed RNA of the proposed operons suggest that the vitamin B1 homeostasis in S. aureus is strongly regulated at transcriptional as well as enzymatic levels.

Highlights

The pathogenic bacterium, Staphylococcus aureus, is responsible for a wide spectrum of human and animal diseases, ranging from benign skin infections to severe diseases, such as arthritis, osteomyelitis, endocarditis and fatal sepsis [1]
Whereas in E. coli thiamine monophosphate (TMP) is subsequently phosphorylated to thiamine pyrophosphate (TPP) by the thiamine phosphate kinase (ThiL) [6], yeast and Plasmodium do not possess ThiL, but instead a thiamine pyrophosphokinase (TPK)
Identification of Genes Involved in Vitamin B1 Metabolism

Summary

Introduction

The pathogenic bacterium, Staphylococcus aureus, is responsible for a wide spectrum of human and animal diseases, ranging from benign skin infections to severe diseases, such as arthritis, osteomyelitis, endocarditis and fatal sepsis [1]. SaTPK accepts only thiamine as substrate and reveals a specific activity of 22 nmol min21 mg21 protein, which is in the same range as the plasmodial counterpart, but approximately onequarter of the mouse TPK [30,31] (Table 1).

Results

Conclusion