Protocatechuate 3,4-Dioxygenase: A Wide Substrate Specificity Enzyme Isolated from <b><i>Stenotrophomonas maltophilia</i></b> KB2 as a Useful Tool in Aromatic Acid Biodegradation

Abstract

Protocatechuate 3,4-dioxygenases (P34Os) catalyze the reaction of the ring cleavage of aromatic acid derivatives. It is a key reaction in many xenobiotic metabolic pathways. P34Os characterize narrow substrate specificity. This property is an unfavorable feature in the biodegradation process because one type of pollution is rarely present in the environment. Thus, the following study aimed at the characterization of a P34O from Stenotrophomonas maltophilia KB2, being able to utilize a wide spectrum of aromatic carboxylic acids. A total of 3 m<smlcap>M</smlcap> vanillic acid and 4-hydroxybenzoate were completely degraded during 8 and 4.5 h, respectively. When cells of strain KB2 were grown on 9 m<smlcap>M</smlcap> 4-hydroxybenzoate, P34O was induced. Biochemical analysis revealed that the examined enzyme was similar to other known P34Os, but showed untypical wide substrate specificity. A high activity of P34O against 2,4- and 3,5-dihydroxybenzoate was observed. As these substrates do not possess ortho configuration hydroxyl groups, it is postulated that their cleavage could be connected with their monodentate binding of substrate to the active site. Since this enzyme characterizes untypical wide substrate specificity it makes it a useful tool in applications for environmental clean-up purposes.

Degradation of 2,4,6-Trinitrotoluene (TNT): Involvement of Protocatechuate 3,4-Dioxygenase (P34O) in Buttiauxella sp. S19-1

“…Perhaps substrates for P34O exclude TNT or ADNT but may include other metabolites that are produced downstream of TNT degradation. P34O has been reported to catalyze the cleavage of aromatic ring structures such as 2,4-hydroxybenzoate, 2,5-dihydroxybenzoate, 2,6-dihydroxybenzoate, 3,5-dihydroxybenzoate, 3,4-dihydroxyhydrocinnamic acid, and other substrates [59], which illustrates that P34O could catalyze not only cleavage of the ortho hydroxyl groups but possibly cleavage of the meta/para hydroxyl groups as well. Therefore, it is possible that 4,6-trihydroxytoluene, and 4-hydroxytoluene could be substrates for P34O.…”

Selective Requirement of the Shikimate Pathway of Legionella pneumophila for Intravacuolar Growth within Human Macrophages but Not within Acanthamoeba

“…Protocatechuate is important in plants and fungi as a precursor or metabolite of a number of phenolic compounds and is itself an antioxidant (56). Protocatechuate is catabolized by the ß-ketoadipate pathway, which is found in a wide variety of soil microbes (56,57), but the L. pneumophila AA100/130b genome does not show the presence of any putative enzyme for this pathway. Therefore, the pathway branch off the shikimate pathway prior to the formation of shikimate is likely required for intramacrophage replication of L. pneumophila, independently of the aromatic amino acids.…”

Draft Genome Sequence of Delftia tsuruhatensis MTQ3, a Strain of Plant Growth-Promoting Rhizobacterium with Antimicrobial Activity

“…Specifically, quercetin dioxygenase (AA671_16710, AA671_18600) is likely a plant microbe-signaling bacterium involved in degrading plant-produced antimicrobial root exudates ( 13 , 14 ). Protocatechuate dioxygenase (AA671_06970, AA671_06975, AA671_20040, AA671_20045, AA671_25085, AA671_25090) may be related to the degradation of aromatic acid ( 15 ). Genes related to the degradation of phenylacetic acid (AA671_06085, AA671_20955, AA671_23770, AA671_24525, AA671_24535) and hydroxyatrazine (AA671_03765) were also identified.…”