Comparative immunological studies on arylsulfatase in bacteria of the family Enterobacteriaceae: occurrence of latent arylsulfatase protein regulated by sulfur compounds and tyramine

Compartmentalization and regulation of arylsulfatase activities in Streptomyces sp., Microbacterium sp. and Rhodococcus sp. soil isolates in response to inorganic sulfate limitation

Arylsulfatases allow microorganisms to satisfy their sulfur (S) requirements as inorganic sulfate after sulfate ester hydrolysis. Our objectives were to investigate the arylsulfatase activities among soil isolates, especially Streptomyces sp., Microbacterium sp. and Rhodococcus sp., because such investigations are limited for these bacteria, which often live in sulfate-limited conditions. Physiological and biochemical analyses indicated that these isolates possessed strong specific arylsulfatase activities ranging from 6 to 8 U. Moreover, for Streptomyces sp., an arylsulfatase localization study revealed 2 forms of arylsulfatases. A first form was located in the membrane, and a second form was located in the intracellular compartment. Both arylsulfatases had different patterns of induction. Indeed, the intracellular arylsulfatase was strictly induced by inorganic sulfate limitation, whereas the membrane arylsulfatase was induced both by substrate presence or S demand independently. For Microbacterium and Rhodococcus isolates, only a membrane arylsulfatase was found. Consequently, our results suggest the presence of a previously undescribed arylsulfatase in these microorganisms that allows them to develop an alternative strategy to fulfill their S requirements compared to bacteria previously studied in the literature.

Sulfatases: Structure, Mechanism, Biological Activity, Inhibition, and Synthetic Utility

Sulfatases, which cleave sulfate esters in biological systems, play a key role in regulating the sulfation states that determine the function of many physiological molecules. Sulfatase substrates range from small cytosolic steroids, such as estrogen sulfate, to complex cell-surface carbohydrates, such as the glycosaminoglycans. The transformation of these molecules has been linked with important cellular functions, including hormone regulation, cellular degradation, and modulation of signaling pathways. Sulfatases have also been implicated in the onset of various pathophysiological conditions, including hormone-dependent cancers, lysosomal storage disorders, developmental abnormalities, and bacterial pathogenesis. These findings have increased interest in sulfatases and in targeting them for therapeutic endeavors. Although numerous sulfatases have been identified, the wide scope of their biological activity is only beginning to emerge. Herein, accounts of the diversity and growing biological relevance of sulfatases are provided along with an overview of the current understanding of sulfatase structure, mechanism, and inhibition.

Biodegradation of aromatic compounds by Escherichia coli

Although Escherichia coli has long been recognized as the best-understood living organism, little was known about its abilities to use aromatic compounds as sole carbon and energy sources. This review gives an extensive overview of the current knowledge of the catabolism of aromatic compounds by E. coli. After giving a general overview of the aromatic compounds that E. coli strains encounter and mineralize in the different habitats that they colonize, we provide an up-to-date status report on the genes and proteins involved in the catabolism of such compounds, namely, several aromatic acids (phenylacetic acid, 3- and 4-hydroxyphenylacetic acid, phenylpropionic acid, 3-hydroxyphenylpropionic acid, and 3-hydroxycinnamic acid) and amines (phenylethylamine, tyramine, and dopamine). Other enzymatic activities acting on aromatic compounds in E. coli are also reviewed and evaluated. The review also reflects the present impact of genomic research and how the analysis of the whole E. coli genome reveals novel aromatic catabolic functions. Moreover, evolutionary considerations derived from sequence comparisons between the aromatic catabolic clusters of E. coli and homologous clusters from an increasing number of bacteria are also discussed. The recent progress in the understanding of the fundamentals that govern the degradation of aromatic compounds in E. coli makes this bacterium a very useful model system to decipher biochemical, genetic, evolutionary, and ecological aspects of the catabolism of such compounds. In the last part of the review, we discuss strategies and concepts to metabolically engineer E. coli to suit specific needs for biodegradation and biotransformation of aromatics and we provide several examples based on selected studies. Finally, conclusions derived from this review may serve as a lead for future research and applications.

Escherichia coli K1 aslA contributes to invasion of brain microvascular endothelial cells in vitro and in vivo

Neonatal Escherichia coli meningitis remains a devastating disease, with unacceptably high morbidity and mortality despite advances in supportive care measures and bactericidal antibiotics. To further our ability to improve the outcome of affected neonates, a better understanding of the pathogenesis of the disease is necessary. To identify potential bacterial genes which contribute to E. coli invasion of the blood-brain barrier, a cerebrospinal fluid isolate of E. coli K1 was mutagenized with TnphoA. TnphoA mutant 27A-6 was found to have a significantly decreased ability to invade brain microvascular endothelial cells compared to the wild type. In vivo, 32% of the animals infected with mutant 27A-6 developed meningitis, compared to 82% of those infected with the parent strain, despite similar levels of bacteremia. The DNA flanking the TnphoA insertion in 27A-6 was cloned and sequenced and determined to be homologous to E. coli K-12 aslA (arylsulfatase-like gene). The deduced amino acid sequence of the E. coli K1 aslA gene product shows homology to a well-characterized arylsulfatase family of enzymes found in eukaryotes, as well as prokaryotes. Two additional aslA mutants were constructed by targeted gene disruption and internal gene deletion. Both of these mutants demonstrated decreased invasion phenotypes, similar to that of TnphoA mutant 27A-6. Complementation of the decreased-invasion phenotypes of these mutants was achieved when aslA was supplied in trans. This is the first demonstration that this locus contributes to invasion of the blood-brain barrier by E. coli K1.

Molecular cloning and site-specific mutagenesis of a gene involved in arylsulfatase production in Campylobacter jejuni

The arylsulfatase gene from Campylobacter jejuni 81-176 encodes a predicted protein of 69,293 Da which shows no sequence similarity with other known arylsulfatases. The gene hybridizes to other Ast+ strains of C. jejuni and Campylobacter sputorum subsp. bubulus, as well as to many Ast- strains of C. jejuni.

Purification and characterization of the arylsulfatase synthesized by Pseudomonas aeruginosa PAO during growth in sulfate-free medium and cloning of the arylsulfatase gene (atsA)

An arylsulfatase (EC 3.1.6.1) was extracted from Pseudomonas aeruginosa PAO1 and purified 2700-fold to homogeneity. Synthesis of this enzyme was repressed when sulfate, cysteine or thiocyanate was supplied as the sole sulfur source for growth, but derepressed with all other sulfur sources tested. The apparent molecular mass was determined by SDS/PAGE to be 57 kDa, and the enzyme was presumed to be a monomer after gel filtration chromatography. The arylsulfatase showed maximal activity at 57 degrees C and pH 8.9, and a Km of 105 microM for 4-nitrocatecholsulfate. Despite previous reports that both inducible and derepressible forms of arylsulfatase exist in P. aeruginosa, we found only one enzyme under a variety of growth conditions: a sulfate-repressed enzyme with a native isoelectric point of 4.76. The gene encoding this enzyme (atsA) was isolated by complementation of a Tn5-751 mutant of P. aeruginosa PAO1. Sequencing revealed a 1602-bp reading frame encoding a 534-amino-acid protein with sequence similarity to known bacterial and eukaryotic arylsulfatases (30-40% and 25-30% identity, respectively), but lacking the signal peptide which is present in all known sequences. The lack of this signal peptide suggests that the P. aeruginosa arylsulfatase is neither periplasmic nor membrane-associated, unlike other known arylsulfatases. The atsA gene was located at 15-17' on the P. aeruginosa genome by Southern hybridization. Only a single copy was observed under moderate stringency conditions.

Microbial metabolism of sulfur- and phosphorus-containing xenobiotics

The enzymes involved in the microbial metabolism of many important phosphorus- or sulfur-containing xenobiotics, including organophosphate insecticides and precursors to organosulfate and organosulfonate detergents and dyestuffs have been characterized. In several instances their genes have been cloned and analysed. For phosphonate xenobiotics, the enzyme system responsible for the cleavage of the carbon-phosphorus bond has not yet been observed in vitro, though much is understood on a genetic level about phosphonate degradation. Phosphonate metabolism is regulated as part of the Pho regulon, under phosphate starvation control. For organophosphorothionate pesticides the situation is not so clear, and the mode of regulation appears to depend on whether the compounds are utilized to provide phosphorus, carbon or sulfur for cell growth. The same is true for organosulfonate metabolism, where different (and differently regulated) enzymatic pathways are involved in the utilization of sulfonates as carbon and as sulfur sources, respectively. Observations at the protein level in a number of bacteria suggest that a regulatory system is present which responds to sulfate limitation and controls the synthesis of proteins involved in providing sulfur to the cell and which may reveal analogies between the regulation of phosphorus and sulfur metabolism.

Analysis of the Escherichia coli genome: DNA sequence of the region from 84.5 to 86.5 minutes

The DNA sequence of 91.4 kilobases of the Escherichia coli K-12 genome, spanning the region between rrnC at 84.5 minutes and rrnA at 86.5 minutes on the genetic map (85 to 87 percent on the physical map), is described. Analysis of this sequence identified 82 potential coding regions (open reading frames) covering 84 percent of the sequenced interval. The arrangement of these open reading frames, together with the consensus promoter sequences and terminator-like sequences found by computer searches, made it possible to assign them to proposed transcriptional units. More than half the open reading frames correlated with known genes or functions suggested by similarity to other sequences. Those remaining encode still unidentified proteins. The sequenced region also contains several RNA genes and two types of repeated sequence elements were found. Intergenic regions include three "gray holes," 0.6 to 0.8 kilobases, with no recognizable functions.

Cloning and nucleotide sequence of a negative regulator gene for Klebsiella aerogenes arylsulfatase synthesis and identification of the gene as folA

A negative regulator gene for synthesis of arylsulfatase in Klebsiella aerogenes was cloned. Deletion analysis showed that the regulator gene was located within a 1.6-kb cloned segment. Transfer of the plasmid, which contains the cloned fragment, into constitutive atsR mutant strains of K. aerogenes resulted in complementation of atsR; the synthesis of arylsulfatase was repressed in the presence of inorganic sulfate or cysteine, and this repression was relieved, in each case, by the addition of tyramine. The nucleotide sequence of the 1.6-kb fragment was determined. From the amino acid sequence deduced from the DNA sequence, we found two open reading frames. One of them lacked the N-terminal region but was highly homologous to the gene which codes for diadenosine tetraphosphatase (apaH) in Escherichia coli. The other open reading frame was located counterclockwise to the apaH-like gene. This gene was highly homologous to the gene which codes for dihydrofolate reductase (folA) in E. coli. We detected 30 times more activity of dihydrofolate reductase in the K. aerogenes strains carrying the plasmid, which contains the arylsulfatase regulator gene, than in the strains without plasmid. Further deletion analysis showed that the K. aerogenes folA gene is consistent with the essential region required for the repression of arylsulfatase synthesis. Transfer of a plasmid containing the E. coli folA gene into atsR mutant cells of K. aerogenes resulted in repression of the arylsulfatase synthesis. Thus, we conclude that the folA gene codes a negative regulator for the ats operon.

A sulfur- and tyramine-regulated Klebsiella aerogenes operon containing the arylsulfatase (atsA) gene and the atsB gene

The structural gene for arylsulfatase (atsA) of Klebsiella aerogenes was cloned into a pKI212 vector in Escherichia coli. Deletion analysis showed that the atsA gene with the promoter region was located within a 3.2-kilobase cloned segment. In E. coli cells which carried the plasmid, the synthesis of arylsulfatase was repressed by various sources of sulfur; the repression was relieved, in each case, by tyramine. Transfer of the plasmid into atsA or constitutive atsR mutant strains of K. aerogenes resulted in complementation of atsA but not of atsR. The nucleotide sequence of the 3.2-kilobase fragment was determined. Two open reading frames, the atsA gene and an unknown gene (atsB), were found. These are located between a potential promoter and a transcriptional terminator sequence. Deletion analysis suggests that atsB is a potential positive factor for the regulation of arylsulfatase. Analysis of the amino acid sequences of the first 13 amino acids from the N terminus of the purified secreted arysulfatase agrees with that of the nucleotide sequence of atsA. The leader peptide extends over 20 amino acids and has the characteristics of a signal sequence. Primer extension mapping of transcripts generated in vivo suggests that the synthesis of mRNA starts at a site 31 or 32 bases upstream from the ATG initiation codon of the atsB gene. By Northern (RNA) blot analysis of the transcripts induced by tyramine, we found a 2.7-kilobase transcript which is identical in size to the total sequence of the atsB and atsA genes. Thus, the ats operon is composed of two cistrons and is regulated by sulfur and tyramine.

[Comparative immunological study of glyceraldehydephosphate dehydrogenase in Enterobacteriaceae: contribution of an anti-glyceraldehydephosphate dehydrogenase antiserum of Enterobacter intermedium]

A comparative immunological study of glyceraldehyde-3-phosphate dehydrogenase among Enterobacteriaceae was carried out with an antiserum against Enterobacter intermedium G-3-PDH. Results of immunodiffusion experiments and microcomplement fixation studies showed E. intermedium to be a homogeneous species. The genera Enterobacter and Escherichia were found to be quite heterogeneous.

Sulfur regulation of heparinase and sulfatases in Flavobacterium heparinum

Sulfur regulation of heparinase synthesis and sulfatase synthesis was studied in Flavobacterium heparinum. Heparinase synthesis was strongly repressed by sulfate and L-cysteine, while the activity of this enzyme showed little or no inhibition by these compounds. Heparinase was synthesized in the absence of heparin when L-methionine was used as the sole sulfur source. The sulfatases produced by F. heparinum, which include the sulfatases involved in heparin catabolism, were also studied. At least some of the sulfatase activity was regulated by sulfur compounds in a manner similar to heparinase regulation. L-Cysteic acid and taurine were not suitable sulfur sources to support the growth of F. heparinum.

Antigenic variability of bacterial RNA polymerases

Radioimmunoassay analysis of enteric and some other Gram-negative bacteria has shown that the antigenic structure of the RNA polymerase alpha subunit is more conserved than that of the beta and beta' subunits. Since anti-alpha antibodies do not affect RNA polymerase activity, the constraints which determine the low variability of the antigenic structure of the alpha subunit are not directly related to its functional role. The antigenic determinants of the alpha subunit located on the surface of the RNA polymerase molecule are more conserved than those involved in contacts with other subunits; an opposite tendency characterizes the beta subunit. The range of variability of the antigenic determinants buried inside the RNA polymerase molecule suggests that the subunits are attached to each other rather loosely. Immunological comparison of RNA polymerases provides a simple method for reconstructing bacterial genealogies. The genealogy of the bacteria examined is essentially in agreement with phylogenetic trees based on 16S and 5S rRNA sequence characterization. This argues against extensive interspecific transfer of genes coding for components of the transcription and translation apparatus.

Introduction of bacteriophage Mu into bacteria of various genera and intergeneric gene transfer by RP4::Mu

The host range of coliphage Mu was greatly expanded to various genera of gram-negative bacteria by using the hybrid plasmic RP4::Mu cts, which is temperature sensitive and which confers resistance to ampicillin, kanamycin, and tetracycline. These drug resistance genes were transferred from Escherichia coli to members of the general Klebsiella, Enterobacter, Citrobacter, Salmonella, Proteus, Erwinia, Serratia, Alcaligenes, Agrobacterium, Rhizobium, Pseudomonas, Acetobacter, and Bacillus. Mu phage was produced by thermal induction from the lysogens of all these drug-resistant bacteria except Bacillus. Mu phage and RP4 or the RP4::Mu plasmid were used to create intergeneric recombinant strains by transfer of some genes, including the arylsulfatase gene, between Klebsiella aerogenes and E. coli. Thus, genetic analysis and intergeneric gene transfer are possible in these RP4::Mu-sensitive bacteria.

Formation and Purification of Serratia marcescens Arylsulfatase

The effects of culture conditions on arylsulfatase production by six strains of the genus Serratia were studied. Synthesis of arylsulfatases in all six strains was repressed in media with inorganic sulfate or methionine as the sole source of sulfur and derepressed by the addition of tyramine. Serratia marcescens IFO 3046 grew most rapidly and produced a high level of arylsulfatase when cultured on mannitol with inorganic sulfate and tyramine. The derepressed synthesis of arylsulfatase in S. marcescens was not subject to strong catabolite repression. The molecular weight of purified arylsulfatase was determined to be between 46,000 and 49,000. Arylsulfatase from S. marcescens differed in K m and V max values, substrate specificities, fluoride inhibition, and electrophoretic mobility from the enzyme from K. aerogenes , but had the same molecular weight as the latter.

Distribution of membrane-bound monoamine oxidase in bacteria

The distribution of membrane-bound monoamine oxidase in 30 strains of various bacteria was studied. Monoamine oxidase was determined by using an ammonia-selective electrode; analyses were sensitive and easy to perform. The enzyme was found in some strains of the family Enterobacteriaceae, such as Klebsiella, Enterobacter, Escherichia, Salmonella, Serratia, and Proteus. Among strains of other families of bacteria tested, only Pseudomonas aeruginosa IFO 3901, Micrococcus luteus IFO 12708, and Brevibacterium ammoniagenes IAM 1641 had monoamine oxidase activity. In all of these bacteria except B. ammoniagenes, monoamine oxidase was induced by tyramine and was highly specific for tyramine, octopamine, dopamine, and norepinephrine. The enzyme in two strains oxidized histamine or benzylamine. Correlations between the distributions of membrane-bound monoamine oxidase and arylsulfatase synthesized in the presence of tyramine were discussed.

Expansion of the host range of coliphage P1 and gene transfer from enteric bacteria to other gram-negative bacteria

The bacterial host range of coliphage P1 was extented by using the heat-inducible phage P1clr100KM. A gene for kanamycin resistance was transferred from Escherichia coli to members of the family Enterobacteriaceae and some other genera of gram-negative bacteria. P1 phage was produced by thermal induction from the lysogens of all these kanamycin-resistant bacteria except some strains.

Arylsulfatase in Salmonella typhimurium: detection and influence of carbon source and tyramine on its synthesis

Arylsulfatase synthesis was shown to occur in Salmonella typhimurium LT2. The enzyme had a molecular weight of approximately 50,000 and was separated into five forms by isoelectrofocusing. The optimal pH for substrate hydrolysis was pH 6.7, with Michaelis constants for nitrocatechol sulfate and nitrophenyl sulfate being 4.1 and 7.9 mM, respectively. Enzyme synthesis was strongly influenced by the presence of tyramine in the growth medium. The uptake of [14C]tyramine and arylsulfatase synthesis were initiated during the second phase of a diauxie growth response, when the organism was cultured with different carbon sources. Adenosine 3',5'-cyclic monophosphoric acid enhanced the uptake of tyramine and the levels of arylsulfatase synthesized. However, the addition of glucose and glycerol to organisms actively transporting tyramine and synthesizing enzyme caused a rapid inhibition of both of these processes. This inhibition was not reversed by adding adenosine 3',5'-cyclic monophosphoric acid. The results suggest that the effect of the carbon source on tyramine transport and arylsulfatase synthesis may be explained in terms of inducer exclusion.

Genetic mapping of tyramine oxidase and arylsulfatase genes and their regulation in intergeneric hybrids of enteric bacteria

The genes for arylsulfatase (atsA) and tyramine oxidase (tynA) have been mapped in Klebsiella aerogenes by P1 transduction. They are linked to gdhD and trp in the order atsA-tynA-gdhD-trp-pyrF. Complementation analysis using F' episomes from Escherichia coli suggested an analogous location of these genes in E. coli, although arylsulfatase activity was not detected in E. coli. P1 phage and F' episomes were used to create intergeneric hybrid strains of enteric bacteria by transfer of the ats and tyn genes between K. aerogenes, E. coli, and Salmonella typhimurium. Intergeneric transduction of the tynK gene from K. aerogenes to an E. coli restrictionless strain was one to two orders less frequent than that of the leuK gene. The tyramine oxidase of E. coli and S. typhimurium in regulatory activity resemble very closely the enzyme of K. aerogenes. The atsE gene from E. coli was expressed, and latent arylsulfatase protein was formed in K. aerogenes and S typhimurium. The results of tyramine oxidase and arylsulfatase synthesis in intergeneric hybrids of enteric bacteria suggest that the system for regulation of enzyme synthesis is conserved more than the structure or function of enzyme protein during evolution.