Anaerobic metabolism of phenol in proteobacteria and further studies of phenylphosphate carboxylase

Abstract

Anaerobic phenol metabolism was studied in three facultative aerobic denitrifying bacteria, Thauera aromatica, "Aromatoleum aromaticum" strain EbN1 (Betaproteobacteria), and Magnetospirillum sp. (Alphaproteobacterium). All species formed phenylphosphate and contained phenylphosphate carboxylase but not phenol carboxylase activity. This is in contrast to direct phenol carboxylation by fermenting bacteria. Antisera raised against subunits of the Thauera phenylphosphate synthase and phenylphosphate carboxylase partly cross-reacted with the corresponding proteins in the other species. Some unsolved features of phenylphosphate carboxylase were addressed in T. aromatica. The core sub-complex of this enzyme consists of three different subunits and catalyzes the exchange of (14)CO(2) with the carboxyl group of 4-hydroxybenzoate, but not phenylphosphate carboxylation. It was inactivated by oxygen or by the oxidizing agent thionin and fully reactivated under reducing conditions. The purified recombinant phosphatase subunit alone had only low phenylphosphate phosphatase activity in the absence of the other components. However, activity was strongly enhanced in the presence of the core enzyme resulting in phenylphosphate carboxylation. Hence, a tight interaction of the carboxylase subunits is required for dephosphorylation of phenylphosphate, which is coupled to the concomitant carboxylation of the produced phenolate to 4-hydroxybenzoate, thus preventing a futile cycle.

Anaerobic Degradation of Benzene and Polycyclic Aromatic Hydrocarbons

“…2 ) [Ahn et al, 2009;Schleinitz et al, 2009;Schmeling and Fuchs, 2009;Schmeling et al, 2004;Schühle and Fuchs, 2004;Suzuki et al, 2014]. However, homologs of the phenylphosphate carboxylase subunits ppcA and ppcD were not identified within the genome of G. metallireducens GS-15 [Schleinitz et al, 2009].…”

“…K + was reported to support the chemical para carboxylation in this biological Kolbe-Schmitt carboxylation. In phenylphosphate carboxylation, the free energy of the phosphate ester hydrolysis shifts the equilibrium towards the carboxylation reaction Schmeling and Fuchs, 2009].…”

Enzymes of anaerobic ethylbenzene and p-ethylphenol catabolism in ‘Aromatoleum aromaticum’: differentiation and differential induction

“…Cells of Escherichia coli strain DH5α were grown aerobically at 37 °C in LB medium (Sambrook and Russell 2001). If required, the growth medium was solidified with 1.5 % (w/v) agar.…”

Bioprospects of Coastal Eubacteria

“…Hydrocarbon-degrading denitrifying bacteria encompass several genera such as Pseudomonas, Azoarcus, Thiosphaera, Thauera, Rhodopseudomonas, Bradyrhizobium, Ochrobactrum, Paracoccus, Mesorhizobium, Ensifer and Acidovorax (Chayabutra and Ju 2000;De Sousa and Bhosle 2012c;Shinoda et al 2004;Song and Ward 2005). Research on Azoarcus vansii, Pseudomonas aeruginosa and Thauera aromatica have led to substantial mechanistic advances in understanding the anaerobic degradation of hydrocarbons (Schmeling and Fuchs 2009;Song and Ward 2005).…”