Phosphorus metabolism

Abstract

Phosphorus (P) is one of the major constituents of the cell, making up about 1.5 to 2.1% of the cell dry weight. Phosphorus occurs in inorganic form as orthophosphate (Pi), pyrophosphate (PPi) or polyphosphate (polyPi) and in numerous organophosphates, such as nucleotides, sugar phosphates, and phospholipids. Major P-containing components of the cells are the polymers RNA, DNA, and polyphosphate. Phosphorus plays a central role in energy metabolism, since the free energy obtained by the oxidation of substrates is used to generate ATP from ADP and Pi. Moreover, many cellular regulatory mechanisms depend on Pi, e.g., in the phosphotransfer reactions of two-component signal transduction systems or of serine/threonine protein kinases. Studies on the P metabolism of Corynebacterium glutamicum were initiated only recently and have focused on polyphosphate metabolism [22], the characterization of pyrophosphatase [32], the definition of the phosphate starvation stimulon [18], and the elucidation of the phosphoproteome [4]. In this chapter, the information on P metabolism deducible from the genome sequence as well as the available experimental data will be summarized.