Heme groups are responsible for carrying out a wide variety of biological functions in

prokaryotes and eukaryotes. These groups are essential for selleckchem respiration, oxygen metabolism and electron transport, as well as for prosthetic groups, hemoglobulins, hydroxylases, catalases, peroxidases and cytochromes [28]. More recently, new roles for heme groups have been described as biosensors of diatomic gases [29, 30] and modulators of protein activity [31]. Protoheme biosynthesis involves seven enzymatic steps, starting 17-AAG manufacturer from the universal precursor delta-aminolevulinic acid (ALA). Other heme groups that cells need are obtained from protoheme modifications. In the step before production of protoheme, an iron ion (Fe2+) is inserted in protoporphyrin IX, catalyzed by ferrochelatase [32]. One of the many roles played by protoheme in the cell is the constitution of cytochrome. Type c cytochromes, which contain a covalent heme c group, are widely distributed in organisms, in which they play a role in photosynthesis and electron transport from the respiratory chain. Most type c cytochromes of E. coli and S. enterica serovar Typhimurium are c552 cytochromes, which are comprised of six covalently bound heme NU7441 nmr groups and are located in the periplasmic space where they act as dissimilatory

nitrite reductase [33]. Therefore, heme groups are used in basic metabolism for energy production, in the electron transport chain in an aerobic pathway, and in the nitrite reduction complex in an anaerobic pathway. The interruption Etoposide price of heme group production thus presumably affects the electron transport chain, which hinders the use of oxygen or nitrate as final electron recipients by cells. If this hypothesis is true, it explains why the mutant 11D09, which carries the interrupted ORF XAC4040, a delta-aminolevulinic dehydratase (hemB), does not cause disease and shows total absence of symptoms. Proteomic analysis showed that proteins involved in glycolytic

and related pathways and fermentation are over-expressed in hemB mutant cells, which show exponential growth, compared to the parental strain [34], indicating that the mutant hemB produces energy only from phosphorylation at the substrate level in vitro. Thus, the observation that the mutant 11D09 is multiplied in planta (Fig. 3) is explained by the use of carbon sources for the production of anaerobic ATP, or even by the use of the hemes produced by the plant. So, considering the information available in the literature, the hemB mutant can survive in vitro and in planta by producing energy from hexoses or from intermediate compounds such as pyruvate, producing lactate, acetyl-CoA, producing ethanol, or L-arginine, producing CO2 + NH4.