Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P51532 (transcriptional activator)
 6,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sphingomonas paucimobilis var. EPA505 utilizes fluoranthene (FLA), naphthalene (NAP), and phenanthrene (PHE) as sole carbon sources for energy and growth. A genetic library of EPA505 was constructed using mini-Tn5 promoter reporter genes encoding for tetracycline resistance (tc(p-)) or luminescence (luxAB(p-)). Out of 2250 Tn5 mutants, ten were deficient in utilization of FLA, NAP, and/or PHE as sole carbon sources. Three classes of Tn5 mutants were defined: classI (nap(-)phe(-)fla(-)), classII (nap(-)phe(-)), and classIII (fla(-)). Four of five mutants in classI did not express dioxygenase function, whereas one classI mutant and all classII and classIII mutants retained dioxygenase activity. In Tn5 tc(p-) classI mutants 200 and 394 (dioxygenase negative) and classII mutant 132 (dioxygenase positive), promoter reporter was expressed when induced with FLA, NAP, PHE, other polycyclic aromatic hydrocarbons (PAHs), and several proposed PAH-derived catabolites. The Tn5 tc(p-) derived classIII mutant 104 was induced only with PAHs and not with PAH-derived catabolites. DNA sequence analysis of cloned regions of classI mutant 200 revealed that Tn5 inserted into a gene that shared (96%) DNA sequence homology with 2,3-dihydroxybiphenyl 1,2-dioxygenase that is designated pbhA. Nucleotide sequences downstream of pbhA shared (84%) homology to a Rieske-type ferredoxin subunit gene of a multicomponent dioxygenase designated pbhB. The Tn5 tc(p-) in classII mutant 132 occurred within sequences that shared (74%) homology with a trans-o-hydroxybenzylidene-pyruvate hydratase-aldolase gene (pbhC). Sequence analysis of the region proximal to this gene revealed a putative promoter that contained a binding site for a LysR transcriptional activator. In classIII mutant 104, the Tn5 tc(p-) resided within a region that shared 94% nucleotide homology to that of a pyruvate phosphate dikinase gene known to be involved in cellular uptake of glucose. The FLA-specific catabolic gene disrupted in mutant 104 was designated phbD. Functional and sequence analyses of promoter probe mutants allowed identification of four genes necessary for the utilization of PAHs that are controlled by at least two promoters that are affected by a wide range of aromatic compounds.
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PMID:Identification of four structural genes and two putative promoters necessary for utilization of naphthalene, phenanthrene, fluoranthene by Sphingomonas paucimobilis var. EPA505. 1113 1

The protocatechuate (PCA) 4,5-cleavage pathway is the essential metabolic route for degradation of low-molecular-weight products derived from lignin by Sphingomonas paucimobilis SYK-6. In the 10.5-kb EcoRI fragment carrying the genes for PCA 4,5-dioxygenase (ligAB), 2-pyrone-4,6-dicarboxylate hydrolase (ligI), 4-oxalomesaconate hydratase (ligJ), and a part of 4-carboxy-2-hydroxymuconate-6-semialdehyde dehydrogenase (ligC), we found the ligK gene, which encodes 4-carboxy-4-hydroxy-2-oxoadipate (CHA) aldolase. The ligK gene was located 1,183 bp upstream of ligI and transcribed in the same direction as ligI. We also found the ligR gene encoding a LysR-type transcriptional activator, which was located 174 bp upstream of ligK. The ligK gene consists of a 684-bp open reading frame encoding a polypeptide with a molecular mass of 24,131 Da. The deduced amino acid sequence of ligK showed 57 to 88% identity with those of the corresponding genes recently reported in Sphingomonas sp. strain LB126, Comamonas testosteroni BR6020, Arthrobacter keyseri 12B, and Pseudomonas ochraceae NGJ1. The ligK gene was expressed in Escherichia coli, and the gene product (LigK) was purified to near homogeneity. Electrospray-ionization mass spectrometry indicated that LigK catalyzes not only the conversion of CHA to pyruvate and oxaloacetate but also that of oxaloacetate to pyruvate and CO(2). LigK is a hexamer, and its isoelectric point is 5.1. The K(m) for CHA and oxaloacetate are 11.2 and 136 micro M, respectively. Inactivation of ligK in S. paucimobilis SYK-6 resulted in the growth deficiency of vanillate and syringate, indicating that ligK encodes the essential CHA aldolase for catabolism of these compounds. Reverse transcription-PCR analysis revealed that the PCA 4,5-cleavage pathway genes of S. paucimobilis SYK-6 consisted of four transcriptional units, including the ligK-orf1-ligI-lsdA cluster, the ligJAB cluster, and the monocistronic ligR and ligC genes.
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PMID:Characterization of the 4-carboxy-4-hydroxy-2-oxoadipate aldolase gene and operon structure of the protocatechuate 4,5-cleavage pathway genes in Sphingomonas paucimobilis SYK-6. 1248 39