Model of 3-HPA and 4-HPA catabolic pathways in <i>B. xenovorans</i> LB400.

<p>Proposed main routes for hydroxyphenylacetates oxidation in LB400 are indicated with thick arrows, whereas the not preferentially oxidation route is indicated with a thin arrow. A, Hydroxyphenylacetates catabolism via <i>ortho</i>-cleavage pathway (continuous line). The substrates and products are: 3-HPA (3-hydroxyphenylacetate); 4-HPA (4-hydroxyphenylacetate); HMG (homogentisate); MA (maleylacetoacetate) and FA (fumarylacetoacetate). The enzymes are MhaAB (3-HPA 6-hydroxylase); HmgA (HMG 1,2-dioxygenase); HmgC (maleylacetate isomerase), HmgB (fumarylacetate hydrolase). B, Hydroxyphenylacetates catabolism via <i>meta</i>-cleavage pathway (dotted line). The metabolites are: HPC (homoprotocatechuate), CHMS (5-carboxymethyl-2-hydroxy-muconic semialdehyde), CHM (5-carboxymethyl-2-hydroxy-muconic acid), OPET (5-oxo-pent-3-ene-1,2,5-tricarboxylic acid), HHDD (2-hydroxy-hept-2,4-diene-1,7-dioic acid), OHED (2-oxo-hept-3-ene-1,7-dioic acid), and HHED (2,4-dihydroxy-hept-2-ene-1,7-dioic acid). The enzymes are HpaBC (4-HPA monooxygenase), HpaD (HPC 2,3-dioxygenase), HpaE (CHMS dehydrogenase), HpaF (CHM isomerase), HpaG (OPET decarboxylase), HpaH (OHED hydratase), HpaI (HHED aldolase), and Sad (succinic semialdehyde dehydrogenase). We propose that in strain LB400 3-HPA is preferentially channeled into the homogentisate central pathway, whereas 4-HPA is channeled actively in both homogentisate and homoprotocatechuate central pathways.