Novel organization of genes in a phthalate degradation operon of Mycobacterium vanbaalenii PYR-1

Abstract

Mycobacterium vanbaalenii PYR-1 is capable of degrading polycyclic aromatic hydrocarbons (PAHs) to ring cleavage metabolites. This study identified and characterized a putative phthalate degradation operon in the M. vanbaalenii PYR-1 genome. A putative regulatory protein ( phtR) was encoded divergently with five tandem genes: phthalate dioxygenase large subunit ( phtAa), small subunit ( phtAb), phthalate dihydrodiol dehydrogenase ( phtB), phthalate dioxygenase ferredoxin subunit ( phtAc) and phthalate dioxygenase ferredoxin reductase ( phtAd ). A 6?7 kb EcoRI fragment containing these genes was cloned into Escherichia coli and converted phthalate to 3,4-dihydroxyphthalate. Homologues to the operon region were detected in a number of PAH-degrading Mycobacterium spp. isolated from various geographical locations. The operon differs from those of other Gram-positive bacteria in both the placement and orientation of the regulatory gene. In addition, the M. vanbaalenii PYR-1 pht operon contains no decarboxylase gene and none was identified within a 37 kb region containing the operon. This study is the first report of a phthalate degradation operon in Mycobacterium spp.

Simultaneous Biodegradation of Polyaromatic Hydrocarbons by a Stenotrophomonas sp: Characterization of nid Genes and Effect of Surfactants on Degradation

“…The genes encoding phthalate biodegradation such as large subunit of phthalate dioxygenase and dihydrodiol dehydrogenase were PCR amplified, cloned and sequenced (results not presented here). These results also found to match the phthalate gene sequences reported from strain PYR-1 [27]. Previous reports [18] suggested that nid genes were located on megaplasmids in Pseudoxanthomonas sp.…”

Bacterial degradation of phthalate isomers and their esters

“…Phthalate 3,4-dioxygenase from Gram positive strains possesses large and small oxygenase subunits including ferridoxin and ferridoxin reductase subunits [16,26,91]. Exceptionally the enzyme from R. erythropolis sp.…”

“…In Mycobacterium vanbaalenii PYR-1 the putative phthalate (pht) operon is located on genome and contain putative regulatory protein gene, phtR, transcribed from the opposite strand and is upstream of the operon [91]. The operon consists of phtAa, phtAb, phtU (an unknown ORF), phtB, phtAc and phtAd and no decarboxylase gene ( Table 2, Fig.…”

“…Genes involved in the metabolism of phthalate isomers are present either on plasmids, chromosome, insertion elements, or both on plasmid and chromosome [11,15,26,39,84,87,91,112]. Compared to terephthalate and isophthalate, phthalate degrading genes are well characterized with respect to their organization and regulation.…”

Functional Identification of OphR, an IclR Family Transcriptional Regulator Involved in the Regulation of the Phthalate Catabolic Operon in Rhodococcus sp. Strain DK17

“…In general, Gram-positive bacteria initially oxidize phthalate to 3,4-dihydro-3,4-dihydroxyphthalate, which is subsequently dehydrogenated and decarboxylated to form protocatechuate [2][3][4]. On the other hand, phthalate degradation in Gramnegative bacteria proceeds through oxygenation and dehydrogenation at carbons 4 and 5 to form 4,5-dihydroxyphthalate, followed by decarboxylation to yield protocatechuate [5].…”