Regulation of catabolic pathways of phenoxyacetic acids and phenols in Alcaligenes eutrophus JMP 134

Abstract

Institllt fUr Mikrobio logie, Univcrsitii t Stuttgart, 0-7000 StUllgart, Federal Republ ic of Ge rmany Abstract. Alicaligenes eulrophus JMP 134 is able to grow on 2,4~dich loro-, 4-chloro-2-methyl· and 2-methylphcnoltY acetic acid . The unsubstilUted phenoxyacetic acid, however, is no growth substrate due to very poor induction of the 2,4-D monooxygenase. Spontaneous mutants of Alcaligene.f eutrophus JMP 134 capable of growth with phenoltyacctic acid were selected on agar pla tes. One of these mutants, designa ted Alcaligenes eJJlrophus JMP 134-1, shows consti· tutive production of six enzymes of the 2,4-D pathway, which were known to be localized in at least tluee different transcriptional units. A common regulatory gene is postu~ lated to be mutated. 2,4~Oichloro-, 4·chloro-2-methyl-and 2-methylphenoxyacctic acid were the inducers of the en~ zymes of the "chloroaromatic pathway" in Alcaligenes eutrophus JMP 134. Phenol and 2-methylphenol. metabolites of the degradation of phenoxyacct ic acid and 2-methyl· phenoxyacetie acid, were shown to be inducers of the mcta-cleavage pathway. whereas 2,4-dichlorophenol and 4-chloro-2-methylphenol were no\. Thus efficient regulation prevents chloroaromatics from being misrouted into the unproductive meta-cleavage pathway. Because 2,4-dichloroand 4-chloro~2 -methylphenol did no t show any induction potential, they were growth substrates only for the mutant strainJMP 134-1.

3-(2-hydroxyphenyl)catechol as substrate for proximal meta ring cleavage in dibenzofuran degradation by Brevibacterium sp. strain DPO 1361

“…One unit of enzyme activity was defined as the amount of enzyme converting 1 xmol of substrate per min. Methods for preparing cell extracts and for measuring protein content were described previously (15,16 (17); and 3-isopropylcatechol (Xmax, 389 nm), 13 cm2 pumol-1 (3). For monitoring enzyme activity during the purification procedures, the enzyme was reactivated by incubating the eluted fractions with a mixture of (NH4)2Fe(SO4)2 (2 mM) and L-ascorbic acid (5 mM) for 30 min.…”

A Gene Cluster Involved in Degradation of Substituted Salicylates viaorthoCleavage inPseudomonassp. Strain MT1 Encodes Enzymes Specifically Adapted for Transformation of 4-Methylcatechol and 3-Methylmuconate

“…Clearly, MT1 uses a similar pathway for degradation of 4-methylmuconolactone by initially isomerizing it into 3-methylmuconolactone. However, in contrast to the situation with C. necator, which also harbors catechol meta cleavage pathways (21,22) and is reported to degrade methylaromatics by both intra-and extradiol cleavage (40,41), MT1 metabolizes methylsalicylates exclusively via the ortho cleavage pathway (Fig. 4).…”

Novel insights into the interplay between peripheral reactions encoded by xyl genes and the chlorocatechol pathway encoded by tfd genes for the degradation of chlorobenzoates by Ralstonia eutropha JMP134

“…The key catabolic abilities of R. eutropha JMP134 are encoded on the plasmid pJP4 (Don & Pemberton, 1981), and the catabolic enzymes and genes of this plasmid have been studied extensively (Don et al, 1985 ; Kasberg et al, 1995 ;Kuhm et al, 1990 ;Laemmli et al, 2000 ;Leveau et al, 1999 ;Matrubutham & Harker, 1994 ; Pe! rez-Pantoja et al, 2000 ;Perkins et al, 1990 ; Pieper et al., 1988Pieper et al, , 1989Pieper et al, , 1993Seibert et al, 1993 ;Streber et al, 1987 ;Vollmer et al, 1999). Metabolism of 3-CB is initiated by the chromosomally encoded, low-specificity benzoate dioxygenase and 1,2-dihydro-1,2-dihydroxybenzene dehydrogenase to form 3-chlorocatechol and 4-chlorocatechol (Fig.…”