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B L Wanner

Publications and source records attributed to B L Wanner.

At least 37 records · Page 2Linked to original sources
PubMed1996

Involvement of the sensor kinase EnvZ in the in vivo activation of the response-regulator PhoB by acetyl phosphate.

Three signalling pathways lead to activation of the phosphate (Pho) regulon by phosphorylation of the response-regulator PhoB in Escherichia coli. One pathway responds to the extracellular inorganic phosphate (PI) level and leads to activation by the Pi sensor kinase, PhoR. The other two pathways are Pi independent and are apparent in the absence of PhoR. One Pi-independent pathway responds to the level of an unknown catabolite and leads to activation by the catabolite regulatory sensor kinase, CreC (originally called PhoM); the other Pi-independent pathway responds to acetyl phosphate and leads to activation by a process requiring acetyl phosphate. Here we show that activation of PhoB by acetyl phosphate can require the sensor kinase EnvZ. Accordingly, we propose that the in vivo activation of PhoB by acetyl phosphate (and perhaps other two-component response-regulators as well) probably always requires a certain kinase that can vary depending upon the growth conditions.

Acetate Kinase↗
PubMed1996

Global analysis of proteins synthesized during phosphorus restriction in Escherichia coli.

The pattern of proteins synthesized in Escherichia coli during steady-state growth in media with ample inorganic phosphate (Pi), upon limitation for Pi (without an alternative phosphorous compound), and during steady-state growth in media containing phosphonate (PHN) as the sole P source was examined by two-dimensional gel electrophoresis. Of 816 proteins monitored in these experiments, all those with differential synthesis rates greater than 2.0 or less than 0.5 upon phosphate limitation (P limitation) or during growth on PHN compared with their rates in the cultures with Pi were classified as belonging to the PL or PHN stimulon, respectively. The PL stimulon included 413 proteins, 208 showing induced synthesis and 205 showing repressed synthesis. The PHN stimulon was smaller: it included 257 proteins; 227 showed induced synthesis and 30 showed repressed synthesis. The overlap of the two stimulons included 137 proteins: most (118) were ones showing induced synthesis. The promoter regions of genes for several of the proteins with induced or repressed synthesis contained sequences which resembled the consensus sequence for PhoB binding. The aggregate mass of proteins responding to P limitation or growth on PHN was 30 to 40% of the cells' total mass. By comparing the proteins responding to P limitation with those responding to growth on PHN, one can speculate which proteins are likely involved in adapting cells to new P sources or in preparing cells to survive stationary phase.

Bacterial Proteins↗
PubMed1995

Cross-talk between the histidine protein kinase VanS and the response regulator PhoB. Characterization and identification of a VanS domain that inhibits activation of PhoB.

VanS is a two-component transmembrane sensory kinase that, together with its response regulator VanR, activates the expression of genes responsible for vancomycin resistance in Enterococcus faecium BM4147. In this report, we demonstrate that the cytoplasmic domain of VanS (including residues Met95 to Ser384) is capable of high level activation (> 500 fold) of the Escherichia coli response regulator PhoB in vivo in the absence of its signaling kinases PhoR, CreC (PhoM), or acetyl phosphate synthesis. In vitro experiments carried out on the purified proteins confirmed that the activation is due to efficient cross-talk between VanS and PhoB, since phospho-VanS catalyzed transfer of its phosphoryl group to PhoB with approximately 90% transfer in 5 min at a 1:4 VanS/PhoB stoichiometry. However, the rate of transfer was at least 100-fold slower than that observed between phospho-VanS and VanR. The in vivo activation of PhoB was used as a reporter system to identify peptide fragments of VanS capable of interfering with activation by VanS(Met95-Ser384), in order to identify an interaction domain. A library of plasmids encoding fragments of VanS(Met95-Ser384) was constructed using transposon mutagenesis, and a subpopulation of these plasmids encoded peptides that interfered with activation of PhoB by VanS(Met95-Ser384). A minimal size fragment (Met95-Ile174) was shown to be both necessary and sufficient for potent inhibition (85%) of this activation.

Amino Acid Sequence↗
PubMed1995

Molecular cloning, mapping, and regulation of Pho regulon genes for phosphonate breakdown by the phosphonatase pathway of Salmonella typhimurium LT2.

Two pathways exist for cleavage of the carbon-phosphorus (C-P) bond of phosphonates, the C-P lyase and the phosphonatase pathways. It was previously demonstrated that Escherichia coli carries genes (named phn) only for the C-P lyase pathway and that Enterobacter aerogenes carries genes for both pathways (K.-S. Lee, W. W. Metcalf, and B. L. Wanner, J. Bacteriol. 174:2501-2510, 1992). In contrast, here it is shown that Salmonella typhimurium LT2 carries genes only for the phosphonatase pathway. Genes for the S. typhimurium phosphonatase pathway were cloned by complementation of E. coli delta phn mutants. Genes for these pathways were proven not to be homologous and to lie in different chromosomal regions. The S. typhimurium phn locus lies near 10 min; the E. coli phn locus lies near 93 min. The S. typhimurium phn gene cluster is about 7.2 kb in length and, on the basis of gene fusion analysis, appears to consist of two (or more) genes or operons that are divergently transcribed. Like that of the E. coli phn locus, the expression of the S. typhimurium phn locus is activated under conditions of Pi limitation and is subject to Pho regulon control. This was shown both by complementation of the appropriate E. coli mutants and by the construction of S. typhimurium mutants with lesions in the phoB and pst loci, which are required for activation and inhibition of Pho regulon gene expression, respectively. Complementation studies indicate that the S. typhimurium phn locus probably includes genes both for phosphonate transport and for catalysis of C-P bond cleavage.

Aminoethylphosphonic Acid↗
PubMed1994

Identification of the DNA-binding site for the phosphorylated VanR protein required for vancomycin resistance in Enterococcus faecium.

The vancomycin resistance operon of Enterococcus faecium encodes a two-component regulatory system comprising VanS and VanR. In vitro experiments showed that about 5% of a labile phosphorylated VanR (P-VanR) was accumulated from ATP and a maltose-binding protein-VanS fusion protein (MBP-VanS). Alternatively, about an 8% abundance of P-VanR was produced with acetyl phosphate. In such incubations, gel shift experiments revealed that P-VanR selectively bound to a 254-bp DNA fragment that contains the vanH promoter for the vanH, vanA, and vanX structural genes. When VanS was added with a mole ratio for VanS:VanR of higher than 1:1, VanS competed with DNA for P-VanR and abolished the gel shift. P-VanR bound 500-fold more tightly to the vanH promoter region, with an estimated EC50 of 40 nM, than the unphosphorylated VanR. A second DNA fragment of 197 bp containing the proposed vanR promoter for the vanR and vanS regulatory genes also exhibited gel shift, but with much lower affinities. A mutant VanR(D53A) was shown to be incompetent for phosphorylation by phosphorylated MBP-VanS or by acetyl phosphate; however, it still bound DNA specifically, albeit with low affinity. DNase I footprinting by P-VanR revealed that a ca. 80-bp region was protected on the vanH promoter and a ca. 40-bp region was protected on the vanR promoter. The unphosphorylated VanR footprinted the same 80 bp on the vanH promoter, but only 20 bp on the vanR promoter.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylation↗
PubMed1994

Use of the rep technique for allele replacement to construct new Escherichia coli hosts for maintenance of R6K gamma origin plasmids at different copy numbers.

Escherichia coli hosts were constructed for maintenance of vectors containing the gamma replication origin of the R6K plasmid (oriRR6K gamma) at different copy numbers (15 or 250/cell). Such vectors require the trans-acting II protein (the pir gene product) for replication. New hosts carry pir+ or pir-116 on the chromosome within uidA, the E. coli gene encoding beta-glucuronidase. They were made using the rep technique for allele replacement and KmR M13 delta uid A::pir+ or M13 delta uidA::pir-116 phage. Because M13 cannot replicate in a rep mutant, KmR transductants arose by integration into the chromosomal uidA locus. Segregants lacking M13 sequences (which were selected as deoxycholate-resistant (DocR) ones) frequently contained delta uidA::pir+ or delta uidA::pir-116 on the chromosome. In principle, this procedure could be used for the introduction of any foreign gene into any nonessential gene on the E. coli chromosome. The delta uidA::pir+ and delta uidA::pir-116 loci were subsequently transferred to a variety of E. coli strains. One such strain is a suppressor-negative one that is especially useful for transposon (Tn) mutagenesis. This strain has an integrated RP4 derivative for conjugative transfer of oriRR6K gamma plasmids also containing oriT from RP4. In addition, new oriRR6K gamma, oriT+ vectors carrying the TcR-encoding genes tetAR from Tn10 are described. These can be used for allele replacement by conjugative transfer of an oriRR6K gamma, oriT+, tetAR plasmid containing a mutated gene into a non-pir recipient and by subsequent selection for Tc-sensitive exconjugants.

Alleles↗
PubMed1994

Molecular genetics of carbon-phosphorus bond cleavage in bacteria.

Phosphonates (Pn) are a large class of organophosphorus molecules that have direct carbon-phosphorus (C-P) bonds in place of the carbon-oxygen-phosphorus ester bond. In bacteria two pathways exist for Pn breakdown for use as a P source: the phosphonatase and C-P lyase pathways. These pathways differ both in regard to their substrate specificity and their cleavage mechanism. The phosphonatase pathway acts on the natural Pn alpha-aminoethylphosphonate (AEPn). In a two-step process it leads to cleavage of the C-P bond by a hydrolysis reaction requiring an adjacent carbonyl group. In contrast the C-P lyase pathway has a broad substrate specificity. It leads to cleavage of substituted Pn (such as AEPn) as well as unsubstituted Pn by a mechanism involving redox or radical chemistry. Due to its broad substrate specificity, the C-P lyase pathway is generally thought to be responsible for the breakdown of Pn herbicides (such as glyphosate) by bacteria. As a way to gain a more in-depth understanding of these Pn degradative pathways, their respective genes have been isolated and characterized. In the absence of a biochemical assay for the C-P lyase pathway such molecular approaches have been especially valuable. The roles of individual genes have been inferred from DNA sequence analysis and mutational effects. Genes for the C-P lyase pathway exist in a fourteen-gene operon that appears to encode both a binding protein-dependent Pn transporter and a C-P lyase. Genes for the phosphonatase pathway also exist in a gene cluster containing Pn uptake and degradative genes. A combination of biochemistry, molecular biology, and molecular genetics approaches has provided more detailed understanding of the mechanisms of C-P bond cleavage. Such basic information may provide a new handle for improvement of Pn degradation capabilities in bacteria, or in other cells in which the respective genes may be introduced and expressed.

Bacteria↗
PubMed1993

Construction of new beta-glucuronidase cassettes for making transcriptional fusions and their use with new methods for allele replacement.

Five cassettes carrying uidA, encoding beta-glucuronidase, were made for the construction of insertion mutants with transcriptional fusions to uidA. Three uidA cassettes contain antibiotic-resistance genes, for chloramphenicol (Cm), for kanamycin (Km) and neomycin (Nm), or for streptomycin (Sm) and spectinomycin (Sp). Some cause polar insertions while others provide a promoter for downstream gene expression. The expression of these uidA cassettes was compared to the expression of lacZ at the same site in phnD, a phosphate-regulated gene for phosphonate use. Several phn::uidA or phn::lacZ insertions were recombined onto the chromosome to test mutational effects and to measure gene expression in single copy. This was done using one of three methods for allele replacement. A new method involved recombination of mutations in M13 onto the chromosome by infection of an Escherichia coli rep mutant that fails to propagate single-stranded DNA phages. Merodiploid recombinants were selected using a resistance marker carried by the M13 phage; segregants lacking M13 sequences were then selected as deoxycholate-resistant (DocR) ones. An improved method for recombination of mutations in pir-dependent, oriR6K vectors involved the use of plasmids containing genes for tetracycline resistance (TcR). Merodiploid recombinants were selected by conjugative transfer of such plasmids into a recipient lacking pir (encoding the pi protein of the R6K plasmid); segregants lacking vector sequences were subsequently selected as Tc-sensitive ones. Both procedures are efficient and allow for recombining marked as well as unmarked mutations onto the chromosome. In addition, some insertions with an antibiotic-resistance marker were directly recombined onto the chromosome by transformation of a recD mutant with linear DNA.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗
PubMed1993

Evidence for a fourteen-gene, phnC to phnP locus for phosphonate metabolism in Escherichia coli.

The Escherichia coli phn (psiD) locus consists of a large gene cluster encoding proteins necessary for the use of phosphonates (Pn) as a sole phosphorus source. On the basis of nucleotide (nt) sequence analysis, the phn locus contains a 12.6-kb operon of seventeen genes named, in alphabetical order, phnA to phnQ [Chen et al., J. Biol. Chem. 265 (1990) 4461-4471]. New Pn+ plasmids were made which are suitable for mutational analysis of this gene cluster. These plasmids contain the R6K origin for DNA replication, can be conjugatively transferred, contain the tetAR genes, and therefore provide a way for allele replacement. The construction of these plasmids showed that phnA and phnB have no role in Pn metabolism. Also, these plasmids were employed to introduce nonpolar phnD::lacZ and phnD::uidA fusions into the chromosome, which allowed us to show that phnD probably has a role in transport. In addition, it was shown that phnP is the most distal gene required for Pn use. This was done by testing the effect of phn::uidA insertions in or near the 3' end of phnP on Pn use. Altogether, these results show that all genes required for Pn use are in the 10.9-kb, fourteen-gene, phnCDEFGHIJKLMNOP locus.

Amino Acid Sequence↗
PubMed1993

Gene regulation by phosphate in enteric bacteria.

The Escherichia coli phosphate (PHO) regulon includes 31 (or more) genes arranged in eight separate operons. All are coregulated by environmental (extra-cellular) phosphate and are probably involved in phosphorus assimilation. Pi control of these genes requires the sensor PhoR, the response regulator PhoB, the binding protein-dependent Pi-specific transporter Pst, and the accessory protein PhoU. During Pi limitation, PhoR turns on genes of the PHO regulon by phosphorylating PhoB that in turn activates transcription by binding to promoters that share an 18-base consensus PHO Box. When Pi is in excess, PhoR, Pst, and PhoU together turn off the PHO regulon, presumably by dephosphorylating PhoB. In addition, two Pi-independent controls that may be forms of cross regulation turn on the PHO regulon in the absence of PhoR. The sensor CreC, formerly called PhoM, phosphorylates PhoB in response to some (unknown) catabolite, while acetyl phosphate may directly phosphorylate PhoB. Cross regulation of the PHO regulon by CreC and acetyl phosphate may be examples of underlying control mechanisms important for the general (global) control of cell growth and metabolism.

Adenosine Triphosphate↗
PubMed1993

Mutational analysis of an Escherichia coli fourteen-gene operon for phosphonate degradation, using TnphoA' elements.

All genes for phosphonate (Pn) utilization in Escherichia coli are in a large cluster of 14 genes named, in alphabetical order, phnC to phnP. Plasmids carrying these genes were mutagenized by using TnphoA'-1, and 43 mutants containing simple insertions were studied in detail. Their insertion sites were defined by restriction mapping and by DNA sequencing. One or more mutations in each phn gene was identified. In 23 mutants, expression of the TnphoA'-1 lacZ gene was phosphate starvation inducible. These mutants had TnphoA'-1 oriented in line behind the phnC promoter, i.e., in the + orientation. In 20 mutants, the TnphoA'-1 lacZ gene was expressed at a low basal level. These mutants had insertions in the opposite orientation. All 43 phn::TnphoA'-1 insertions were recombined onto the chromosome to test for mutational effects, and their structures on the chromosome were verified by DNA hybridization. Those in the + orientation were switched to TnphoA'-9, which has an outward promoter for expression of downstream genes. These insertions were tested for polar effects by measuring beta-glucuronidase synthesis from a uidA gene transcriptionally fused to the 3' end of the phnP gene. The results indicate the following: (i) the phnC-to-phnP gene cluster is an operon of 14 genes, and the phnC promoter is the sole psi promoter; (ii) three gene products (PhnC, PhnD, and PhnE) probably constitute a binding protein-dependent Pn transporter; (iii) seven gene products (PhnG, PhnH, PhnI, PhnJ, PhnK, PhnL, and PhnM) are required for catalysis and are likely to constitute a membrane-associated carbon-phosphorus (C-P) lyase; (iv) two gene products (PhnN and PhnP) are not absolutely required and may therefore be accessory proteins for the C-P lyase; and (v) two gene products (PhnF and PhnO) are not required for Pn use and may have a regulatory role because they have sequence similarities to regulatory proteins. The mechanism for breaking the C-P bond by a lyase is discussed in light of these results.

Biodegradation, Environmental↗
PubMed1993

Use of the rep technique for allele replacement to construct mutants with deletions of the pstSCAB-phoU operon: evidence of a new role for the PhoU protein in the phosphate regulon.

The phosphate regulon is negatively regulated by the PstSCAB transporter and PhoU protein by a mechanism that may involve protein-protein interaction(s) between them and the Pi sensor protein, PhoR. In order to study such presumed interaction(s), mutants with defined deletions of the pstSCAB-phoU operon were made. This was done by construction of M13 recombinant phage carrying these mutations and by recombination of them onto the chromosome by using a rep host (which cannot replicate M13) for allele replacement. These mutants were used to show that delta (pstSCAB-phoU) and delta (pstB-phoU) mutations abolished Pi uptake by the PstSCAB transporter, as expected, and that delta phoU mutations had no effect on uptake. Unexpectedly, delta phoU mutations had a severe growth defect, and this growth defect was (largely) alleviated by a compensatory mutation in the pstSCAB genes or in the phoBR operon, whose gene products positively regulate expression of the pstSCAB-phoU operon. Because delta phoU mutants that synthesize a functional PstSCAB transporter constitutively grew extremely poorly, the PhoU protein must have a new role, in addition to its role as a negative regulator. A role for the PhoU protein in intracellular Pi metabolism is proposed. Further, our results contradict those of M. Muda, N. N. Rao, and A. Torriani (J. Bacteriol. 174:8057-8064, 1992), who reported that the PhoU protein was required for Pi uptake.

Alleles↗
PubMed1992

Molecular genetic studies of a 10.9-kb operon in Escherichia coli for phosphonate uptake and biodegradation.

Bacteria that use phosphonates as a phosphorus source must be able to break the stable carbon-phosphorus bond. In Escherichia coli phosphonates are broken down by a C-P lyase that has a broad substrate specificity. Evidence for a lyase is based on in vivo studies of product formation because it has been proven difficult to detect the activity in vitro. By using molecular genetic techniques, we have studied the genes for phosphonate uptake and degradation in E. coli, which are organized in an operon of 14 genes, named phnC to phnP. As expected for genes involved in P acquisition, the phnC-phnP operon is a member of the PHO regulon and is induced many hundred-fold during phosphate limitation. Three gene products (PhnC, PhnD and PhnE) comprise a binding protein-dependent phosphonate transporter, which also transports phosphate, phosphite, and certain phosphate esters such as phosphoserine; two gene products (PhnF and PhnO) may have a role in gene regulation; and nine gene products (PhnG, PhnH, PhnI, PhnJ, PhnK, PhnL, PhnM, PhnN, and PhnP) probably comprise a membrane-associated C-P lyase enzyme complex. Although E. coli can degrade many different phosphonates, the ability to use certain phosphonates appears to be limited by the specificity of the PhnCDE transporter and not by the specificity of the C-P lyase.

Biodegradation, Environmental↗
PubMed1992

TnphoA and TnphoA' elements for making and switching fusions for study of transcription, translation, and cell surface localization.

We describe a set of elements based on the transposon TnphoA for making transcriptional fusions to the lacZ gene and for making translational fusions to the phoA or lacZ structural gene. Each element can be switched, one for another, by homologous recombination, thereby allowing testing for transcription, translation, or cell surface localization determinants at the same site within a gene. We describe three kinds of elements for making each fusion type. Two kinds are transposition proficient (Tnp+): one encodes kanamycin resistance, and the other encodes tetracycline resistance. The third kind is transposition defective (Tnp-) and encodes kanamycin resistance. In addition, we describe one Tnp- element that has no reporter gene and encodes chloramphenicol resistance; this element is used primarily as a tool to aid in switching fusions. Switching is efficient because each element has in common 254 bp of DNA at the phoA end and 187 bp (or more) of DNA at the IS50R end of TnphoA, and switching is straightforward because individual elements encode different drug resistances. Thus, switched recombinants can be selected as drug-resistant transductants, and they can be recognized as ones that have lost the parental drug resistance and fusion phenotype. Further, switching Tnp+ elements to Tnp- elements reduces problems due to transposition that can arise in P1 crosses or cloning experiments. Some TnphoA and TnphoA' elements cause polar mutations, while others provide an outward promoter for downstream transcription. This feature is especially useful in the determination of operon structures. Strategies for the use of TnphoA and TnphoA' elements in gene analysis are also described.

Amino Acid Sequence↗
PubMed1992

Role of phosphorylated metabolic intermediates in the regulation of glutamine synthetase synthesis in Escherichia coli.

Transcription of the Ntr regulon is controlled by the two-component system consisting of the response regulator NRI (NtrC) and the kinase/phosphatase NRII (NtrB), which both phosphorylates and dephosphorylates NRI. Even though in vitro transcription from nitrogen-regulated promoters requires phosphorylated NRI, NRII-independent activation of NRI also occurs in vivo. We show here that this activation likely involves acetyl phosphate; it is eliminated by mutations that reduce synthesis of acetyl phosphate and is elevated by a mutation expected to cause accumulation of acetyl phosphate. With purified components, we investigated the mechanism by which acetyl phosphate stimulates glutamine synthetase synthesis. Acetyl phosphate, carbamyl phosphate, and phosphoramidate but not ATP or phosphoenolpyruvate acted as substrates for the autophosphorylation of NRI in vitro. Phosphorylated NRI produced by this mechanism exhibited the properties associated with NRI phosphorylated by NRII, including the activated ATPase activity of the central domain of NRI and the ability to activate transcription from the nitrogen-regulated glutamine synthetase glnAp2 promoter.

Adenosine Triphosphatases↗
PubMed1992

Involvement of phosphotransacetylase, acetate kinase, and acetyl phosphate synthesis in control of the phosphate regulon in Escherichia coli.

Two controls of the phosphate (PHO) regulon require sensor proteins that are protein kinases that phosphorylate the regulator, PhoB, which in turn activates transcription only when phosphorylated. Pi control requires the Pi sensor PhoR; the other control is Pi independent and requires the sensor CreC (formerly called PhoM). Here we describe an additional control of the PHO regulon which is Pi independent and requires neither PhoR nor CreC. This control is regulated by a two-step pathway in carbon metabolism in which acetyl coenzyme A, Pi, and ADP are converted into acetate, coenzyme A, and ATP via the enzymes phosphotransacetylase (Pta) and acetate kinase (AckA). It responds to the synthesis of acetyl phosphate, an intermediate in the Pta-AckA pathway. Since the synthesis of acetyl phosphate via this pathway leads to the incorporation of Pi into ATP, the primary phosphoryl donor in metabolism, we propose that a regulatory coupling(s) may exist between the PHO regulon, which encodes genes for Pi uptake, and genes for enzymes in central metabolism for incorporation of Pi into ATP. Regulatory interactions of this sort may be important in global control. Further, it provides a functional basis for the concept of cross-regulation in the PHO regulon. This is also the first evidence that acetyl phosphate may have a role as an effector of gene regulation.

Acetate Kinase↗
PubMed1992

Evidence for two phosphonate degradative pathways in Enterobacter aerogenes.

We screened mini-Mu plasmid libraries from Enterobacter aerogenes IFO 12010 for plasmids that complement Escherichia coli phn mutants that cannot use phosphonates (Pn) as the sole source of phosphorus (P). We isolated two kinds of plasmids that, unexpectedly, encode genes for different metabolic pathways. One kind complements E. coli mutants with both Pn transport and Pn catalysis genes deleted; these plasmids allow degradation of the 2-carbon-substituted Pn alpha-aminoethylphosphonate but not of unsubstituted alkyl Pn. This substrate specificity is characteristic of a phosphonatase pathway, which is absent in E. coli. The other kind complements E. coli mutants with Pn catalysis genes deleted but not those with both transport and catalysis genes deleted; these plasmids allow degradation of both substituted and unsubstituted Pn. Such a broad substrate specificity is characteristic of a carbon-phosphorus (C-P) lyase pathway, which is common in gram-negative bacteria, including E. coli. Further proof that the two kinds of plasmids encode genes for different pathways was demonstrated by the lack of DNA homology between the plasmids. In particular, the phosphonatase clone from E. aerogenes failed to hybridize to the E. coli phnCDEFGHIJKLMNOP gene cluster for Pn uptake and degradation, while the E. aerogenes C-P lyase clone hybridized strongly to the E. coli phnGHIJKLM genes encoding C-P lyase but not to the E. coli phnCDE genes encoding Pn transport. Specific hybridization by the E. aerogenes C-P lyase plasmid to the E. coli phnF, phnN, phnO, and phnP genes was not determined. Furthermore, we showed that one or more genes encoding the apparent E. aerogenes phosphonatase pathway, like the E. coli phnC-to-phnP gene cluster, is under phosphate regulon control in E. coli. This highlights the importance of Pn in bacterial P assimilation in nature.

Chromosome Deletion↗