Substrate Specificity and Expression of Three 2,3-Dihydroxybiphenyl 1,2-Dioxygenases from
            <i>Rhodococcus globerulus</i>
            Strain P6

McKay, David; Prucha, Matthias; Reineke, Walter; Timmis, Kenneth N.; Pieper, Dietmar H.

doi:10.1128/jb.185.9.2944-2951.2003

Cited by 58 publications

(40 citation statements)

References 41 publications

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“…Overall, the present data agree reasonably well with steadystate kinetic parameters and relative activities reported by McKay et al (24). Both studies evaluated the steady-state kinetic parameters of DHBD P6 -I and -III for DHB and 2Ј-and 3Ј-Cl DHB.…”

Section: Discussionsupporting

confidence: 81%

“…Based on the higher specificity of these enzymes for some Cl DHBs than for unchlorinated DHB, it has been suggested that they may have been recruited by R. globerulus P6 to improve its PCB degradation (24,37). However, the present results demonstrate that relatively high specificity constants for Cl DHBs are not unique to the single-domain DHBDs.…”

Section: Discussioncontrasting

confidence: 48%

“…Moreover, the activities of the latter enzymes are relatively low compared to those of the two-domain enzymes. Finally, conditions under which DHBD P6 -III is expressed in R. globerulus P6 have yet to be identified (24). It is possible that the primary physiological role of DHBD P6 -II and -III is not biphenyl catabolism or PCB transformation.…”

Section: Discussionmentioning

confidence: 99%

“…1) (20). McKay et al (24) demonstrated that five DHBDs (the four mentioned above and DHBD P6 -II) have different reactivities with Cl DHBs. However, the results of these studies are harder to interpret, as the authors used partially inactive enzyme preparations and did not take into account the effects of oxidative inactivation of the enzymes during catalytic turnover.…”

mentioning

confidence: 99%

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Evolutionarily Divergent Extradiol Dioxygenases Possess Higher Specificities for Polychlorinated Biphenyl Metabolites

Fortin

Haro

et al. 2005

J Bacteriol

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The reactivities of four evolutionarily divergent extradiol dioxygenases towards mono-, di-, and trichlorinated (triCl) 2,3-dihydroxybiphenyls (DHBs) were investigated: 2,3-dihydroxybiphenyl dioxygenase (EC 1.13.11.39) from Burkholderia sp. strain LB400 (DHBD LB400 ), DHBD P6 -I and DHBD P6 -III from Rhodococcus globerulus P6, and 2,2,3-trihydroxybiphenyl dioxygenase from Sphingomonas sp. strain RW1 (THBD RW1 ). The specificity of each isozyme for particular DHBs differed by up to 3 orders of magnitude. Interestingly, the K m app values of each isozyme for the tested polychlorinated DHBs were invariably lower than those of monochlorinated DHBs. Moreover, each enzyme cleaved at least one of the tested chlorinated (Cl) DHBs better than it cleaved DHB (e.g., apparent specificity constants for 3,5-dichlorinated [diCl] DHB were 2 to 13.4 times higher than for DHB). These results are consistent with structural data and modeling studies which indicate that the substrate-binding pocket of the DHBDs is hydrophobic and can accommodate the Cl DHBs, particularly in the distal portion of the pocket. Although the activity of DHBD P6 -III was generally lower than that of the other three enzymes, six of eight tested Cl DHBs were better substrates for DHBD P6 -III than was DHB. Indeed, DHBD P6 -III had the highest apparent specificity for 4,3,5-triCl DHB and cleaved this compound better than two of the other enzymes. Of the four enzymes, THBD RW1 had the highest specificity for 2-Cl DHB and was at least five times more resistant to inactivation by 2-Cl DHB, consistent with the similarity between the latter and 2,2,3-trihydroxybiphenyl. Nonetheless, THBD RW1 had the lowest specificity for 2,6-diCl DHB and, like the other enzymes, was unable to cleave this critical PCB metabolite (k cat app < 0.001 s ؊1 ).

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Section: Discussionsupporting

confidence: 81%

Section: Discussioncontrasting

confidence: 48%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Evolutionarily Divergent Extradiol Dioxygenases Possess Higher Specificities for Polychlorinated Biphenyl Metabolites

Fortin

Haro

et al. 2005

J Bacteriol

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“…Cell extracts were prepared as previously described (39). Protein concentrations were determined by the Bradford method (6).…”

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confidence: 99%

Two Angular Dioxygenases Contribute to the Metabolic Versatility of Dibenzofuran-Degrading Rhodococcus sp. Strain HA01

Aly¹,

Huu²,

Wray

et al. 2008

Appl Environ Microbiol

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Rhodococcus sp. strain HA01, isolated through its ability to utilize dibenzofuran (DBF) as the sole carbon and energy source, was also capable, albeit with low activity, of transforming dibenzo-p-dioxin (DD). This strain could also transform 3-chlorodibenzofuran (3CDBF), mainly by angular oxygenation at the ether bond-carrying carbon (the angular position) and an adjacent carbon atom, to 4-chlorosalicylate as the end product. Similarly, 2-chlorodibenzofuran (2CDBF) was transformed to 5-chlorosalicylate. However, lateral oxygenation at the 3,4-positions was also observed and yielded the novel product 2-chloro-3,4-dihydro-3,4-dihydroxydibenzofuran. Two gene clusters encoding enzymes for angular oxygenation (dfdA1A2A3A4 and dbfA1A2) were isolated, and expression of both was observed during growth on DBF. Heterologous expression revealed that both oxygenase systems catalyze angular oxygenation of DBF and DD but exhibited complementary substrate specificity with respect to CDBF transformation. While DfdA1A2A3A4 oxygenase, with high similarity to DfdA1A2A3A4 oxygenase from Terrabacter sp. strain YK3, transforms 3CDBF by angular dioxygenation at a rate of 29% ؎ 4% that of DBF, 2CDBF was not transformed. In contrast, DbfA1A2 oxygenase, with high similarity to the DbfA1A2 oxygenase from Terrabacter sp. strain DBF63, exhibited complementary activity with angular oxygenase activity against 2CDBF but negligible activity against 3CDBF. Thus, Rhodococcus sp. strain HA01 constitutes the first described example of a bacterial strain where coexpression of two angular dioxygenases was observed. Such complementary activity allows for the efficient transformation of chlorinated DBFs.Biarylethers, comprising dibenzo-p-dioxin (DD), dibenzofuran (DBF), diphenyl ether, and their halogenated derivatives, are widespread environmental pollutants. Polychlorinated DDs and DBFs, the contaminating by-products formed during the manufacture of pesticides or the incineration of industrial and domestic wastes, can cause a wide range of serious health effects (1,4,13).Microorganisms play important roles in the degradation and mineralization of xenobiotic and aromatic compounds in natural environments. Their aerobic degradation is frequently initiated by Rieske nonheme iron oxygenases which catalyze the incorporation of two oxygen atoms into the aromatic ring to form arene cis-diols (15). This is then followed by a dehydrogenation reaction catalyzed by a cis-dihydrodiol dehydrogenase to give catechol or substituted catechols, which serve as substrates for oxygenolytic aromatic ring cleavage. Rieske nonheme iron oxygenases are typically composed of a terminal oxygenase (iron-sulfur protein) and different electron transport proteins (8). The catalytic iron-sulfur proteins are homoor heteromultimers with the ␣-subunit containing a Riesketype [2Fe-2S] cluster, a mononuclear nonheme iron oxygen activation center, and a substrate-binding site (8) that is responsible for substrate specificity (15). Comparison of the amino acid sequences of the ␣-subunits ...

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Survey of the year 2003 commercial optical biosensor literature

2005

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In the year 2003 there was a 17% increase in the number of publications citing work performed using optical biosensor technology compared with the previous year. We collated the 962 total papers for 2003, identified the geographical regions where the work was performed, highlighted the instrument types on which it was carried out, and segregated the papers by biological system. In this overview, we spotlight 13 papers that should be on everyone's 'must read' list for 2003 and provide examples of how to identify and interpret high-quality biosensor data. Although we still find that the literature is replete with poorly performed experiments, over-interpreted results and a general lack of understanding of data analysis, we are optimistic that these shortcomings will be addressed as biosensor technology continues to mature.

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Substrate Specificity and Expression of Three 2,3-Dihydroxybiphenyl 1,2-Dioxygenases from Rhodococcus globerulus Strain P6

Cited by 58 publications

References 41 publications

Evolutionarily Divergent Extradiol Dioxygenases Possess Higher Specificities for Polychlorinated Biphenyl Metabolites

Evolutionarily Divergent Extradiol Dioxygenases Possess Higher Specificities for Polychlorinated Biphenyl Metabolites

Two Angular Dioxygenases Contribute to the Metabolic Versatility of Dibenzofuran-Degrading Rhodococcus sp. Strain HA01

Survey of the year 2003 commercial optical biosensor literature

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