Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.5.1.4 (deaminase)
 5,113 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The gene queD encoding quercetinase of Streptomyces sp. FLA, a soil isolate related to S. eurythermus (T), was identified. Quercetinases catalyze the 2,4-dioxygenolytic cleavage of 3,5,7,3',4'-pentahydroxyflavone to 2-protocatechuoylphloroglucinol carboxylic acid and carbon monoxide. The queD gene was expressed in S. lividans and E. coli, and the recombinant hexahistidine-tagged protein (QueDHis(6)) was purified. Several flavonols were converted by QueDHis(6), whereas CO formation from the 2,3-dihydroflavonol taxifolin and the flavone luteolin were not observed. In contrast to bicupin quercetinases from Aspergillus japonicus and Bacillus subtilis, and bicupin pirins showing quercetinase activity, QueD of strain FLA is a monocupin exhibiting 35.9% sequence identity to the C-terminal domain of B. subtilis quercetinase. Its native molecular mass of 63 kDa suggests a multimeric protein. A queD-specific probe hybridized with fragments of genomic DNA of four other quercetin degrading Streptomyces strains, but not with DNA of B. subtilis. Potential ORFs upstream of queD probably code for a serine protease and an endoribonuclease; two ORFs downstream of queD may encode an amidohydrolase and a carboxylesterase. This arrangement suggests that queD is not part of a catabolic gene cluster. Quercetinases might play a major role as detoxifying rather than catabolic enzymes.
 ...
PMID:A new monocupin quercetinase of Streptomyces sp. FLA: identification and heterologous expression of the queD gene and activity of the recombinant enzyme towards different flavonols. 1751 49

Quercetinase, catalyzing the 2,4-dioxygenolytic cleavage of the flavonol quercetin (3,5,7,3',4'-pentahydroxyflavone) to carbon monoxide and 2-protocatechuoylphloroglucinol carboxylic acid, is encoded by the queD gene in Streptomyces sp. FLA. Because studies on the transcriptional regulation of quercetinase genes are rare, we analyzed the expression of queD in response to quercetin and other carbon compounds. RNA hybridization experiments revealed that transcription of queD is triggered by quercetin and its 3-O-rhamnosylglucoside rutin, but not by the flavonol morin (3,5,7,2',4'-pentahydroxyflavone), the presumed quercetin degradation products protocatechuate and 2,4,6-trihydroxybenzoate or the sugars rhamnose and glucose. Quercetin-induced queD expression was not influenced by the presence of Ni(II), the preferred cofactor of Streptomyces QueD. Reverse transcription-PCR analysis showed a concerted transcription of queD and two putative genes located downstream of queD, which were predicted to code for an amidohydrolase and an esterase. By determination of the transcriptional start site of the queD operon, putative -10 and -35 regions could be identified, suggesting transcription from a sigma70-dependent promoter. Sequence analysis of the queD promoter region indicated possible binding sites for an LmrA/YxaF-like repressor.
 ...
PMID:Transcriptional analysis of the queD gene coding for quercetinase of Streptomyces sp. FLA. 1868 65