scholarly journals The Alkene Monooxygenase from Xanthobacter Strain Py2 Is Closely Related to Aromatic Monooxygenases and Catalyzes Aromatic Monohydroxylation of Benzene, Toluene, and Phenol

1999 ◽  
Vol 65 (4) ◽  
pp. 1589-1595 ◽  
Author(s):  
Ning-Yi Zhou ◽  
Alister Jenkins ◽  
Chan K. N. Chan Kwo Chion ◽  
David J. Leak
Keyword(s):  
Consensus Sequence ◽  
Detailed Comparison ◽  
Amino Acid Sequences ◽  
Effector Protein ◽  
Chromosomal Dna ◽  
Α Subunit ◽  
Γ Subunit ◽  
Genes Encoding ◽  
Benzene Toluene ◽  
Α Subunits

ABSTRACT The genes encoding the six polypeptide components of the alkene monooxygenase from Xanthobacter strain Py2 (Xamo) have been located on a 4.9-kb fragment of chromosomal DNA previously cloned in cosmid pNY2. Sequencing and analysis of the predicted amino acid sequences indicate that the components of Xamo are homologous to those of the aromatic monooxygenases, toluene 2-, 3-, and 4-monooxygenase and benzene monooxygenase, and that the gene order is identical. The genes and predicted polypeptides are aamA, encoding the 497-residue oxygenase α-subunit (XamoA); aamB, encoding the 88-residue oxygenase γ-subunit (XamoB); aamC, encoding the 122-residue ferredoxin (XamoC); aamD, encoding the 101-residue coupling or effector protein (XamoD); aamE, encoding the 341-residue oxygenase β-subunit (XamoE); andaamF, encoding the 327-residue reductase (XamoF). A sequence with >60% concurrence with the consensus sequence of ς54 (RpoN)-dependent promoters was identified upstream of the aamA gene. Detailed comparison of XamoA with the oxygenase α-subunits from aromatic monooxygenases, phenol hydroxylases, methane monooxygenase, and the alkene monooxygenase fromRhodococcus rhodochrous B276 showed that, despite the overall similarity to the aromatic monooxygenases, XamoA has some distinctive characteristics of the oxygenases which oxidize aliphatic, and particularly alkene, substrates. On the basis of the similarity between Xamo and the aromatic monooxygenases, Xanthobacterstrain Py2 was tested and shown to oxidize benzene, toluene, and phenol, while the alkene monooxygenase-negative mutants NZ1 and NZ2 did not. Benzene was oxidized to phenol, which accumulated transiently before being further oxidized. Toluene was oxidized to a mixture ofo-, m-, and p-cresols (39.8, 18, and 41.7%, respectively) and a small amount (0.5%) of benzyl alcohol, none of which were further oxidized. In growth studiesXanthobacter strain Py2 was found to grow on phenol and catechol but not on benzene or toluene; growth on phenol required a functional alkene monooxygenase. However, there is no evidence of genes encoding steps in the metabolism of catechol in the vicinity of theaam gene cluster. This suggests that the inducer specificity of the alkene monooxygenase may have evolved to benefit from the naturally broad substrate specificity of this class of monooxygenase and the ability of the host strain to grow on catechol.

scholarly journals Human epithelial Na+ channel missense variants identified in the GenSalt study alter channel activity

2016 ◽  
Vol 311 (5) ◽  
pp. F908-F914 ◽  
Author(s):  
Evan C. Ray ◽  
Jingxin Chen ◽  
Tanika N. Kelly ◽  
Jiang He ◽  
L. Lee Hamm ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Cell Surface ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Channel Activity ◽  
Dietary Salt ◽  
Α Subunit ◽  
Γ Subunit ◽  
Genes Encoding ◽  
Altered Sensitivity

Mutations in genes encoding subunits of the epithelial Na+ channel (ENaC) can cause early onset familial hypertension, demonstrating the importance of this channel in modulating blood pressure. It remains unclear whether other genetic variants resulting in subtler alterations of channel function result in hypertension or altered sensitivity of blood pressure to dietary salt. This study sought to identify functional human ENaC variants to examine how these variants alter channel activity and to explore whether these variants are associated with altered sensitivity of blood pressure to dietary salt. Six-hundred participants of the Genetic Epidemiology Network of Salt Sensitivity (GenSalt) study with salt-sensitive or salt-resistant blood pressure underwent sequencing of the genes encoding ENaC subunits. Functional effects of identified variants were examined in a Xenopus oocyte expression system. Variants that increased channel activity included three in the gene encoding the α-subunit (αS115N, αR476W, and αV481M), one in the β-subunit (βS635N), and one in the γ-subunit (γL438Q). One α-subunit variant (αA334T) and one γ-subunit variant (βD31N) decreased channel activity. Several α-subunit extracellular domain variants altered channel inhibition by extracellular Na+ (Na+ self-inhibition). One variant (αA334T) decreased and one (αV481M) increased cell surface expression. Association between these variants and salt sensitivity did not reach statistical significance. This study identifies novel functional human ENaC variants and demonstrates that some variants alter channel cell surface expression and/or Na+ self-inhibition.

scholarly journals The α- and β-subunits of the Human UDP-N-acetylglucosamine:Lysosomal Enzyme Phosphotransferase Are Encoded by a Single cDNA

2005 ◽  
Vol 280 (43) ◽  
pp. 36141-36149 ◽  
Author(s):  
Mariko Kudo ◽  
Ming Bao ◽  
Anil D'Souza ◽  
Fu Ying ◽  
Huaqin Pan ◽  
...  
Keyword(s):  
Amino Acid ◽  
Catalytic Domain ◽  
Amino Acid Sequences ◽  
Subunit Structure ◽  
Bac Clone ◽  
Significant Similarity ◽  
Α Subunit ◽  
Γ Subunit ◽  
Mannose 6 Phosphate ◽  
Α And Β Subunits

Lysosomal enzymes are targeted to the lysosome through binding to mannose 6-phosphate receptors because their glycans are modified with mannose 6-phosphate. This modification is catalyzed by UDP-N-acetylglucosamine:lysosomal enzyme N-acetylglucosamine-1-phosphotransferase (GlcNAc-phosphotransferase). Bovine GlcNAc-phosphotransferase was isolated using monoclonal antibody affinity chromatography, and an α2β2γ2-subunit structure was proposed. Although cDNA encoding the γ-subunit has been described, cDNAs for the α- and β-subunits have not. Using partial amino acid sequences from the bovine α- and β-subunits, we have isolated a human cDNA that encodes both the α- and β-subunits. Both subunits contain a single predicted membrane-spanning domain. The α- and β-subunits appear to be generated by a proteolytic cleavage at the Lys928-Asp929 bond. Transfection of 293T cells with the α/β-subunits-precursor cDNA with or without the γ-subunit cDNA results in a 3.6- or 17-fold increase in GlcNAc-phosphotransferase activity in cell lysates, suggesting that the precursor cDNA contains the catalytic domain. The sequence lacks significant similarity with any described vertebrate enzyme except for two Notch-like repeats in the α-subunit. However, a 112-amino acid sequence is highly similar to a group of bacterial capsular polymerases (46% identity). A BAC clone containing the gene that spanned 85.3 kb and was composed of 21 exons was sequenced and localized to chromosome 12q23. We now report the cloning of both the cDNA and genomic DNA of the precursor of Glc-NAc-phosphotransferase. The completion of cloning all three subunits of GlcNAc-phosphotransferase allows expression of recombinant enzyme and dissection of lysosomal targeting disorders.

scholarly journals Benzylsuccinate Synthase of Azoarcussp. Strain T: Cloning, Sequencing, Transcriptional Organization, and Its Role in Anaerobic Toluene and m-Xylene Mineralization

2001 ◽  
Vol 183 (23) ◽  
pp. 6763-6770 ◽  
Author(s):  
Gypsy R. Achong ◽  
Ana M. Rodriguez ◽  
Alfred M. Spormann
Keyword(s):  
Response Regulator ◽  
Transcriptional Start Site ◽  
Amino Acid Sequences ◽  
Α Subunit ◽  
Reverse Transcription Pcr ◽  
Thauera Aromatica ◽  
Regulatory Systems ◽  
Site Mapping ◽  
Genes Encoding ◽  
Benzylsuccinate Synthase

ABSTRACT Biochemical studies in Azoarcus sp. strain T have demonstrated that anaerobic oxidation of both toluene andm-xylene is initiated by addition of the aromatic hydrocarbon to fumarate, forming benzylsuccinate and 3-methyl benzylsuccinate, respectively. Partially purified benzylsuccinate synthase was previously shown to catalyze both of these addition reactions. In this study, we identified and sequenced the genes encoding benzylsuccinate synthase from Azoarcus sp. strain T and examined the role of this enzyme in both anaerobic toluene and m-xylene mineralization. Based on reverse transcription-PCR experiments and transcriptional start site mapping, we found that the structural genes encoding benzylsuccinate synthase,bssCAB, together with two additional genes,bssD and bssE, were organized in an operon in the order bssDCABE. bssD is believed to encode an activating enzyme, similar in function to pyruvate formate-lyase activase. bssE shows homology to tutHfrom Thauera aromatica strain T1, whose function is currently unknown. A second operon that is upstream ofbssDCABE and divergently transcribed contains two genes,tdiS and tdiR. The predicted amino acid sequences show similarity to sensor kinase and response regulator proteins of prokaryotic two-component regulatory systems. A chromosomal null bssA mutant was constructed (the bssAgene encodes the α-subunit of benzylsuccinate synthase). ThisbssA null mutant strain was unable to grow under denitrifying conditions on either toluene or m-xylene, while growth on benzoate was unaffected. The growth phenotype of the ΔbssA mutant could be rescued by reintroducingbssA in trans. These results demonstrate that benzylsuccinate synthase catalyzes the first step in anaerobic mineralization of both toluene and m-xylene.

scholarly journals Nucleotide sequence of the Klebsiella pneumoniae nifD gene and predicted amino acid sequence of the α-subunit of nitrogenase MoFe protein

1987 ◽  
Vol 247 (2) ◽  
pp. 287-291 ◽  
Author(s):  
I Ioannidis ◽  
M Buck
Keyword(s):  
Amino Acid ◽  
Nucleotide Sequence ◽  
Klebsiella Pneumoniae ◽  
Amino Acid Sequences ◽  
Alpha Subunit ◽  
Predicted Amino Acid Sequence ◽  
Structural Homology ◽  
Α Subunit ◽  
Mofe Protein ◽  
Genes Encoding

The nucleotide sequence of the Klebsiella pneumoniae nifD gene is presented and together with the accompanying paper [Holland, Zilberstein, Zamir & Sussman (1987) Biochem. J. 247, 277-285] completes the sequence of the nifHDK genes encoding the nitrogenase polypeptides. The K. pneumoniae nifD gene encodes the 483-amino acid-residue nitrogenase alpha-subunit polypeptide of Mr 54156. The alpha-subunit has five strongly conserved cysteine residues at positions 63, 89, 155, 184 and 275, some occurring in a region showing both primary sequence and potential structural homology to the K. pneumoniae nitrogenase beta-subunit. A comparison with six other alpha-subunit amino acid sequences has been made, which indicates a number of potentially important domains within alpha-subunits.

Location of subunits in the acetylcholine receptor by analysis of electron images of tubular crystals from Torpedo marmorata

1996 ◽  
Vol 54 ◽  
pp. 70-71
Author(s):  
David A. Burkwall ◽  
Robert Josephs ◽  
Jennifer Holly ◽  
David Richman ◽  
Robert Fairclough
Keyword(s):  
Acetylcholine Receptor ◽  
Torpedo Marmorata ◽  
Central Cavity ◽  
Α Subunit ◽  
Γ Subunit ◽  
Disulphide Bonds ◽  
Selective Channel ◽  
Polypeptide Chains ◽  
Tubular Crystals ◽  
Α Subunits

The nicotinic acetylcholine receptor(AChR) is a membrane protein containing four different homologous polypeptide chains (two copies of an α-subunit and single copies of β, γ, and δ). These subunits assemble about a central cavity, which is thought to delineate the ion-selective channel. In tubular crystals from T. marmorata receptors normally exist as dimers, paired through disulphide bonds between the δ-subunits. Conflicting reports still arise concerning the relative locations of these subunits around the central axis. It has been proposed that the β-subunit lies between the two α-subunits or that the γ subunit lies between the two α-subunits. Here we examine the locus of two subunit-specific labels, mAb 383C and 247G, bound to receptors and averaged in each case from over 5,000 molecules.

scholarly journals Genome-Wide Identification of Targets for the Archaeal Heat Shock Regulator Phr by Cell-Free Transcription of Genomic DNA

2009 ◽  
Vol 192 (5) ◽  
pp. 1292-1298 ◽  
Author(s):  
Annette M. Keese ◽  
Gerrit J. Schut ◽  
Mohamed Ouhammouch ◽  
Michael W. W. Adams ◽  
Michael Thomm
Keyword(s):  
Heat Shock ◽  
Pyrococcus Furiosus ◽  
Inositol Phosphate ◽  
Consensus Sequence ◽  
Small Heat Shock Protein ◽  
Open Reading Frames ◽  
Chromosomal Dna ◽  
Genes Encoding ◽  
High Conservation

ABSTRACT The hyperthermophilic archaeon Pyrococcus furiosus grows optimally near 100°C and undergoes a heat shock response at 105°C, mediated at least in part by the heat shock regulator Phr. Genes encoding a small heat shock protein (HSP20) and a member of the AAA+ ATPase are the only known targets of the regulator, but a genetic mutant of Phr has yet to be characterized. We describe here an alternative approach for the identification of the regulon of Phr based on cell-free transcription of fragmented chromosomal DNA in the presence or absence of the regulator and hybridization of in vitro RNA to P. furiosus whole-genome microarrays. Our results confirmed the phr, the hsp20, and the aaa + ATPase genes as targets of Phr and also identified six additional open reading frames, PF0624, PF1042, PF1291, PF1292, PF1488, and PF1616, as Phr-responsive genes, which include that encoding di-myo-inositol phosphate synthase. Transcription of the identified novel genes was inhibited by Phr in standard transcription assays, and the novel consensus sequence 5′-TTTAnnnACnnnnnGTnAnnAAAA-3′ (uppercase letters denote a high conservation of the bases) was inferred from our data as the Phr recognition motif. Mutational evidence for the significance of this sequence as Phr recognition was provided in DNA-binding experiments.

scholarly journals Molecular Cloning, Nucleotide Sequence, and Expression of Genes Encoding a Polycyclic Aromatic Ring Dioxygenase from Mycobacterium sp. Strain PYR-1

2001 ◽  
Vol 67 (8) ◽  
pp. 3577-3585 ◽  
Author(s):  
Ashraf A. Khan ◽  
Rong-Fu Wang ◽  
Wei-Wen Cao ◽  
Daniel R. Doerge ◽  
David Wennerstrom ◽  
...  
Keyword(s):  
Genomic Library ◽  
Terminal Sequence ◽  
Α Subunit ◽  
Pah Degradation ◽  
Expression Of Genes ◽  
Genes Encoding ◽  
Polycyclic Aromatic ◽  
2D Gel ◽  
Α Subunits ◽  
Induced Proteins

ABSTRACT Mycobacterium sp. strain PYR-1 degrades high-molecular-weight polycyclic hydrocarbons (PAHs) primarily through the introduction of both atoms of molecular oxygen by a dioxygenase. To clone the dioxygenase genes involved in PAH degradation, two-dimensional (2D) gel electrophoresis of PAH-induced proteins from cultures of Mycobacterium sp. strain PYR-1 was used to detect proteins that increased after phenanthrene, dibenzothiophene, and pyrene exposure. Comparison of proteins from induced and uninduced cultures on 2D gels indicated that at least six major proteins were expressed (105, 81, 52, 50, 43, and 13 kDa). The N-terminal sequence of the 50-kDa protein was similar to those of other dioxygenases. A digoxigenin-labeled oligonucleotide probe designed from this protein sequence was used to screen dioxygenase-positive clones from a genomic library of Mycobacterium sp. strain PYR-1. Three clones, each containing a 5,288-bp DNA insert with three genes of the dioxygenase system, were obtained. The genes in the DNA insert, from the 5′ to the 3′ direction, were a dehydrogenase, the dioxygenase small (β)-subunit, and the dioxygenase large (α)-subunit genes, arranged in a sequence different from those of genes encoding other bacterial dioxygenase systems. Phylogenetic analysis showed that the large α subunit did not cluster with most of the known α-subunit sequences but rather with three newly described α subunits of dioxygenases from Rhodococcus spp. andNocardioides spp. The genes fromMycobacterium sp. strain PYR-1 were subcloned and overexpressed in Escherichia coli with the pBAD/ThioFusion system. The functionality of the genes for PAH degradation was confirmed in a phagemid clone containing all three genes, as well as in plasmid subclones containing the two genes encoding the dioxygenase subunits.

V. The epithelial sodium channel and its implication in human diseases

1999 ◽  
Vol 276 (3) ◽  
pp. G567-G571 ◽  
Author(s):  
Edith Hummler ◽  
Jean-Daniel Horisberger
Keyword(s):  
Distal Colon ◽  
Loss Of Function ◽  
Newborn Mice ◽  
Α Subunit ◽  
Salt Wasting ◽  
Lung Fluid ◽  
Wasting Syndrome ◽  
Rate Limiting Step ◽  
Γ Subunit ◽  
Rate Limiting

The epithelial Na+ channel (ENaC) controls the rate-limiting step in the process of transepithelial Na+ reabsorption in the distal nephron, the distal colon, and the airways. Hereditary salt-losing syndromes have been ascribed to loss of function mutations in the α-, β-, or γ-ENaC subunit genes, whereas gain of function mutations (located in the COOH terminus of the β- or γ-subunit) result in hypertension due to Na+ retention (Liddle’s syndrome). In mice, gene-targeting experiments have shown that, in addition to the kidney salt-wasting phenotype, ENaC was essential for lung fluid clearance in newborn mice. Disruption of the α-subunit resulted in a complete abolition of ENaC-mediated Na+ transport, whereas knockout of the β- or γ-subunit had only minor effects on fluid clearance in lung. Disruption of each of the three subunits resulted in a salt-wasting syndrome similar to that observed in humans.

scholarly journals Genes encoding components of the olfactory signal transduction cascade contain a DNA binding site that may direct neuronal expression.

1993 ◽  
Vol 13 (9) ◽  
pp. 5805-5813 ◽  
Author(s):  
M M Wang ◽  
R Y Tsai ◽  
K A Schrader ◽  
R R Reed
Keyword(s):  
Signal Transduction ◽  
Dna Binding ◽  
Binding Site ◽  
Binding Sites ◽  
Consensus Sequence ◽  
Initiation Site ◽  
Olfactory Neuron ◽  
Promoter Regions ◽  
Transcriptional Initiation ◽  
Genes Encoding

Genes which mediate odorant signal transduction are expressed at high levels in neurons of the olfactory epithelium. The molecular mechanism governing the restricted expression of these genes likely involves tissue-specific DNA binding proteins which coordinately activate transcription through sequence-specific interactions with olfactory promoter regions. We have identified binding sites for the olfactory neuron-specific transcription factor, Olf-1, in the sequences surrounding the transcriptional initiation site of five olfactory neuron-specific genes. The Olf-1 binding sites described define the consensus sequence YTCCCYRGGGAR. In addition, we have identified a second binding site, the U site, in the olfactory cyclic nucleotide gated channel and type III cyclase promoters, which binds factors present in all tissue examined. These experiments support a model in which expression of Olf-1 in the sensory neurons coordinately activates a set of olfactory neuron-specific genes. Furthermore, expression of a subset of these genes may be modulated by additional binding factors.

scholarly journals Regulatory Mechanisms Controlling Expression of the DAN/TIR Mannoprotein Genes During Anaerobic Remodeling of the Cell Wall in Saccharomyces cerevisiae

Genetics ◽  
2001 ◽  
Vol 157 (3) ◽  
pp. 1169-1177
Author(s):  
Natalia E Abramova ◽  
Brian D Cohen ◽  
Odeniel Sertil ◽  
Rachna Kapoor ◽  
Kelvin J A Davies ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Consensus Sequence ◽  
Ectopic Expression ◽  
Constitutive Expression ◽  
Anaerobic Growth ◽  
Zinc Cluster ◽  
Sterol Transport ◽  
Genes Encoding ◽  
Altered Regulation ◽  
Repression Domain

Abstract The DAN/TIR genes of Saccharomyces cerevisiae encode homologous mannoproteins, some of which are essential for anaerobic growth. Expression of these genes is induced during anaerobiosis and in some cases during cold shock. We show that several heme-responsive mechanisms combine to regulate DAN/TIR gene expression. The first mechanism employs two repression factors, Mox1 and Mox2, and an activation factor, Mox4 (for mannoprotein regulation by oxygen). The genes encoding these proteins were identified by selecting for recessive mutants with altered regulation of a dan1::ura3 fusion. MOX4 is identical to UPC2, encoding a binucleate zinc cluster protein controlling expression of an anaerobic sterol transport system. Mox4/Upc2 is required for expression of all the DAN/TIR genes. It appears to act through a consensus sequence termed the AR1 site, as does Mox2. The noninducible mox4Δ allele was epistatic to the constitutive mox1 and mox2 mutations, suggesting that Mox1 and Mox2 modulate activation by Mox4 in a heme-dependent fashion. Mutations in a putative repression domain in Mox4 caused constitutive expression of the DAN/TIR genes, indicating a role for this domain in heme repression. MOX4 expression is induced both in anaerobic and cold-shocked cells, so heme may also regulate DAN/TIR expression through inhibition of expression of MOX4. Indeed, ectopic expression of MOX4 in aerobic cells resulted in partially constitutive expression of DAN1. Heme also regulates expression of some of the DAN/TIR genes through the Rox7 repressor, which also controls expression of the hypoxic gene ANB1. In addition Rox1, another heme-responsive repressor, and the global repressors Tup1 and Ssn6 are also required for full aerobic repression of these genes.

Sign in / Sign up

Export Citation Format

Share Document