Laboratoire de Biologie et Génétique Moléculaire, Institut de Génétique et Microbiologie, CNRS UMR8621 Bâtiment 400, Université Paris-Sud, F-91405 Orsay Cedex, France1
Author for correspondence: Marie-Joelle Virolle. Tel: +33 169156913. Fax: +33 169156678. e-mail: virolle{at}igmors.u-psud.fr
![]() |
ABSTRACT |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Keywords: glucose repression, induction, inositol monophosphatase, transition phase
Abbreviations: Amp, ampicillin; Apr, apramycin; CBS, Cibachron blue starch; IMP, inositol monophosphatase; Nos, nosiheptide
The EMBL accession number for the sequence reported in this paper is AJ223365.
![]() |
INTRODUCTION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
When cultures of S. lividans TK24(pTS6000) are grown in the presence of a non-repressive carbon source such as glycerol or mannitol, expression of aml is switched on at a low level at the end of the exponential phase of growth, even in the absence of exogenous inducer. Adding a low level of exogenous inducer (10-4 M maltotriose) to cultures growing exponentially in a glycerol medium does not induce aml expression, whereas adding the exogenous inducer after the growth-phase-dependent aml expression has started clearly enhances aml expression. Both growth-phase-related and maltotriose-inducible aml expression are strongly repressed in the presence of glucose (Virolle & Gagnat, 1994 ). The molecular mechanisms responsible for growth-phase-dependent aml expression are not yet elucidated, but could be related to growth-phase-dependent degradation of the internal storage compound glycogen. This degradation might provide the maltodextrins inducing, at a low level, the different components of the maltose regulon. Low level induction of the maltose transport system, and thus the transport of external inducer, could account for the growth-phase-related pattern of aml inducibility.
For more insight into the molecular mechanisms involved in glucose repression of aml expression, we developed a transposon mutagenesis procedure yielding S. lividans mutants in which aml expression had become insensitive to glucose repression. In this paper, we report the characterization of one such mutant. The interrupted gene, called sblA, was cloned and sequenced and its transcription was investigated. Effects of the sblA null mutation on growth and aml expression in different culture conditions are reported.
![]() |
METHODS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
Transposon mutagenesis.
The delivery plasmid pCZA168 (Solenberg & Baltz, 1991 ), carrying the tsr gene that confers resistance to nosiheptide (Nos) in Streptomyces and the transposon Tn5096 harbouring the aacC4 gene that confers resistance to geneticin (G418) in both streptomycetes and E. coli, was used in transposon mutagenesis. Protoplasts of strain TK24(pTS6000) were transformed by pCZA168, plated on R2YE medium (Hopwood et al., 1985
) and overlaid with SNA (Hopwood et al., 1985
) containing Nos (50 µg ml-1). Spores from the transformants were spread on solid defined agar to obtain separate colonies. This minimal agar consisted of a basal layer (20 ml) of minimal agar (Hopwood et al., 1985
) containing 1% glucose, 0·25% (w/v) Casamino acids and G418 (15 µg ml-1) to maintain selective pressure for the presence of Tn5096, and a top layer (5 ml) of the same medium containing 2% (w/v) Cibachron blue starch (CBS), as a chromogenic substrate for
-amylase (Klein et al., 1969
). These cultures, called CBS plates, were incubated for 3 d at 30 °C (no haloes were seen), then for 23 weeks at 40 °C. At this non-permissive temperature for pCZA168 replication, colonies stopped growing uniformly in diameter, but after 1 week, most of them had grown sectors (a mean of four per colony), 12% of which were surrounded by white haloes of CBS hydrolysis and were considered to be potentially interesting mutants. Mycelium from these sectors was streaked on the same medium to confirm their phenotype.
Chemicals and enzymes.
G418 was purchased from Sigma and Nos was a generous gift from Rhône-Poulenc. Restriction enzymes, DNA ligase and T4 polynucleotide kinase were used according to the recommendations of the suppliers (Boehringer Mannheim and Biolab).
DNA manipulation.
Total genomic DNA and plasmid DNA were isolated from S. lividans TK24(pTS6000) as described by Hopwood et al. (1985 ). Methods for plasmid isolation from E. coli, purification of DNA fragments, preparation of DNA probes, Southern blotting or colony hybridization were as described by Sambrook et al. (1989
).
Procedure used to clone the transposon bordering sequences
Total DNA of the chosen mutant was cut by BamHI [a BamHI site is located downstream of the 3' end of the aacC4 gene of Tn5096] and BgIII (this site is absent in Tn5096). Fragments were ligated into the BamHI site of pBR322 (Bolivar et al., 1977 ) and the ligation mix was used to transform competent E. coli DH5
cells. Transformant colonies were selected on agar media containing G418 (30 µg ml-1). Plasmid DNA was extracted from 24 independent transformants and was digested with PstI (site located near one end of Tn5096, Fig. 1a
) and SmaI or SalI (two enzymes that cut streptomycete DNA frequently). Analysis of restriction patterns by agarose gel electrophoresis revealed two different types of bordering sequences. They were sequenced using the oligonucleotide OTN 1 (5'-TCAAGTCCTGGCGACTCCTTCGCAGGCTCCGTTGCTCGAC-3'), which is complementary to the sequence downstream of the NruI site of Tn5096 (Fig. 1a
). One type of bordering sequence was shown to be pCZA168 DNA whereas the other was bona fide chromosomal DNA. The pBR322 derivative carrying the chromosomal DNA was called p6998 (Fig. 1a
). To clone the gene interrupted by the transposon, a mini-library of the approximately 2 kb SphIBglII chromosomal DNA fragments from S. lividans was constructed in pIJ2925 (Janssen & Bibb, 1985
) and probed with the 440 bp SalISalI fragment I of p6998.
|
RNA isolation and transcriptional analysis.
RNA was prepared as described by Hopwood et al. (1985 ) except that a DNase I treatment was used in addition to salt precipitation. RNA used for Northern blot analysis was prepared from transition-phase cultures grown in NMMP with 1% (w/v) mannitol as the carbon source. RNA used for high-resolution nuclease S1 mapping was kindly provided by Eriko Takano (John Innes Institute, Norwich, UK). It was prepared from cultures grown in SMM medium (Takano et al., 1992
) and sampled at intervals during the exponential, transition and stationary phases.
For Northern blot analysis, total RNA was denatured with glyoxal/dimethylsulfoxide (DMSO), fractionated on 1% agarose gels, transferred to Hybond-N membrane and hybridized at 65 °C with the 563 bp BclI no. 3NotI no. 10 fragment labelled with [-32P]dCTP using the T7 quick prime kit (Pharmacia). Molecular mass standards from BRL were treated in the same way as the RNA samples and labelled as DNA probes.
The DNA fragment used in high-resolution nuclease S1 mapping was the PCR fragment synthesized using the -180 reverse primer (5'-ATGCAGCTGGCACGACAGGT-3') showing complementarity to pUC18, and the 5'-CGATCGCGACTTCGGTGTCGTCGTG-3' oligonucleotide showing complementarity to the sblA region boxed in Fig. 2. It was phosphorylated at its 5' end with [
-32P]ATP; 40 µg total RNA was hybridized with 50 nmol labelled probe (corresponding to approximately 104 Cerenkov counts min-1) in NaTCA buffer (Murray, 1986
) at 45 °C overnight after denaturation at 70 °C for 10 min. All subsequent steps were carried out as described by Strauch et al. (1991
) using S1 nuclease from Pharmacia. As a sequencing template, p7000 double-stranded DNA was used with the oligonucleotide mentioned above phosphorylated at its 5' end with [
-32P]ATP. The sequence ladders were run in parallel with the S1 protected products. The resulting polyacrylamide gel was dried, exposed for 72 h and scanned with a phosphor imager.
|
Determination of the chromosomal location of sblA by PFGE.
Chromosomal DNAs of S. lividans TK24(pTS6000) and S. lividans TK24(pTS6000) sblA::aac were digested with AseI or DraI as described by Leblond et al. (1990
). The DNA fragments were separated on 1 or 1·3% agarose gels by PFGE. Electrophoresis buffer contained 20 mM triethanolamine (Fluka), 8·75 mM acetic acid and 1·5 mM EDTA. Electrophoresis was carried out for 30 h with pulse times of 60 s for the AseI digests and 200 s for the DraI digests.
![]() |
RESULTS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Mutants of TK24(pTS6000) producing -amylase on glucose plates were isolated by transposon mutagenesis using Tn5096 carried by pCZA168 (Solenberg & Baltz, 1991
). Tn5096 is derived from the insertion sequence IS493 (Solenberg et al., 1989
) present at three copies in the S. lividans TK24 chromosome. All the mutants isolated were apramycin (Apr)-resistant (Tn5096 marker) and NosR (plasmid marker), suggesting that, besides true transposition events, integration of pCZA168 into the chromosome via homologous recombination between Tn5096 and one of the three chromosomal copies of IS493 had occurred.
Cloning of the gene interrupted by Tn5096: nucleotide sequence and similarities between the deduced protein and database proteins
For the chosen mutant, the Tn5096 bordering sequences were first cloned into pBR322 by taking advantage of the presence of aacC4 in the transposon. Of the two types of bordering sequences obtained, one was, as expected, pCZA168 DNA, whereas the other was bona fide chromosomal DNA. The pBR322 derivative carrying the chromosomal sequences flanking the Tn5096 insertion on one side was called p6998 (Fig. 1a). The 440 bp SalISalI fragment I of p6998 was used as a probe to screen an E. coli mini-library of the approximately 2 kb SphIBglII chromosomal DNA fragments from S. lividans. Two positive clones with the same 2 kb SphIBglII insert were isolated. The restriction map of the insert is shown in Fig. 1b
. The resulting plasmid was called p7000 and its insert was sequenced.
The sequence of the ORF interrupted by Tn5096 is shown in Fig. 2. Comparison of this sequence with the transposon flanking sequence identified the exact insertion point (position 540) of Tn5096. The interrupted ORF starts with a GTG in position 259 and ends with a TGA in position 1080. No typical Streptomyces RBS could be found in the vicinity of the putative GTG start codon. The 72% G+C content of this ORF is in good agreement with the mean G+C content of Streptomyces DNA. Codon usage is extremely biased toward G or C (93·8%) at the third position of the triplet (Bibb et al., 1984
).
The ORF encodes 274 amino acids. Searches using the gap-blast program (Altschul et al., 1997 ) indicated that the sequence shared similarities with proteins belonging to the inositol monophosphatase (IMP) family (Fig. 3
). The greatest similarity was to the product of the suhB gene of E. coli (Yano et al., 1990
) (30·8% identity and 48·8% similarity). This ORF was thus called sblA for suhB-like. SuhB has IMP activity but exhibits quite a broad range of substrate specificity (Matsuhisa et al., 1995
) and its biological role is not yet clearly understood. Furthermore, SblA shared significant similarity (29·7% identity and 54·2% similarity) with the product of the impA gene of Mycobacterium smegmatis encoding an IMP (Parish et al., 1997
), and with three proteins from various Streptomyces species. These three proteins are encoded by genes belonging to two different antibiotic biosynthetic pathways. One is encoded by pur3 (29·8% identity and 48·6% similarity), a gene belonging to the puromycin biosynthetic cluster of Streptomyces alboniger and thought to be a phosphatase acting on one of the precursors of puromycin (Tercero et al., 1996
). The other two are encoded by strO, a gene belonging to the streptomycin biosynthetic cluster of Streptomyces glaucescens (30·2% identity and 53% similarity) or Streptomyces griseus (28% identity and 51% similarity) and thought to encode an N-amidino-scyllo-inosamine-4-phosphate phosphatase (Ahlert et al., 1997
).
|
Transcriptional regulation of sblA expression
Northern blot analysis indicated that sblA was transcribed as unique monocistronic mRNA of approximately 840 bp (Fig. 4). Therefore, the mutant phenotype linked to the interruption of sblA was likely to be due to the inactivation of the gene itself and not to a polar effect on downstream sequences.
|
|
|
Effects of sblA disruption on growth
S. lividans TK24(pTS6000) sblA::aac had the same mutant phenotype as the initial transposition mutant (Fig. 6
). Colonies of TK24(pTS6000) sblA::
aac were smaller on glucose plates than those of the corresponding wild-type strain, whereas no such growth difference was seen on glycerol plates (data not shown). Growth curves of S. lividans TK24(pTS6000) and TK24(pTS6000) sblA::
aac were established in NMMP (Hopwood et al., 1985
) in the presence of 1% glucose or glycerol as carbon sources (Fig. 7
). Glucose-grown cultures of the wild-type strain showed higher biomass production than glycerol-grown cultures. Growth rates of glycerol- or glucose-grown cultures of the mutant were comparable to those of the wild-type during exponential growth. However, glucose-grown cultures of the sblA mutant reproducibly entered earlier into stationary phase than the glucose-grown wild-type cultures. This premature growth arrest led to a 25% deficit in biomass compared with the wild-type strain.
|
|
Similarly, the very weak amylolytic activity of S. lividans TK24 was clearly enhanced in S. lividans TK24 sblA::aac on the CBS plates in the presence of glucose (Fig. 6
). The interruption of sblA thus had a similar effect on the expression of endogenous amylolytic genes of S. lividans to that on the heterologous aml gene.
![]() |
DISCUSSION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
sblA constitutes the fourth characterized locus involved in the regulation of aml expression. The three other loci are the glkA gene encoding the glucose kinase in S. coelicolor (Ikeda et al., 1984 ; Virolle & Gagnat, 1994
), the LacI-like negative transcriptional regulator called Reg1 in S. lividans (Nguyen et al., 1997
) and the Reg1 operator sites located in the aml promoter region (Virolle & Gagnat, 1994
; Nguyen, 1999
). In a strain of S. coelicolor mutated for the glkA gene, glucose repression of aml expression is abolished but the derepressed aml expression is further inducible by a low level of exogenous inducer (Virolle & Bibb, 1988
). In S. lividans, the interruption of reg1 (Nguyen et al., 1997
) or the deletion of operator-like sequences located in the aml promoter region and constituting the Reg 1-binding site (Virolle & Gagnat, 1994
; Nguyen, 1999
) concomitantly abolishes both maltodextrin induction and glucose repression of aml expression. Similarly, in S. coelicolor, the interruption of gylR and malR encoding the negative transcriptional regulators of the glycerol operon gylXABC (Hindle & Smith, 1994
) and the maltose transport operon malEFG (van Wezel et al., 1997
), respectively, and the mutation of operator-like sequences located in the promoter region of chi (encoding chitinase) from Streptomyces plicatus (Delic et al., 1992
; Ni & Westpheling, 1997
) concomitantly abolish both substrate induction and glucose repression of these genes and operons. These observations suggest either that inducer exclusion is the main mechanism contributing to catabolite repression in Streptomyces or that the specific negative transcriptional regulators are mediating the process. The latter situation would be unusual since in E. coli or Bacillus subtilis catabolite repression is mainly mediated by the presence or absence of positive or negative pleiotropic transcriptional regulators, the cAMPCRP (cAMP receptor protein) complex and CcpA, respectively (Saier et al., 1995
). Nevertheless, the contribution to catabolite repression of specific regulators containing a phosphotransferase system regulation domain (PRD regulators) has been demonstrated in B. subtilis (Stulke et al., 1998
).
The apparent relief of catabolite repression of aml expression observed in the sblA mutant strain is not easy to rationalize. It could simply be due to an absence of glucose transport/metabolism resulting from the early growth arrest characteristic of this mutant. Nevertheless, in the sblA mutant, Reg1, the negative transcriptional regulator of aml expression has obviously less affinity for its binding sites than in the wild-type strain. The affinity of transcriptional regulators for their target sites could be modulated by many mechanisms. A classical way is the binding of an effector molecule inducing a conformational change leading to the reduction or the enhancement of the affinity of the transcriptional regulators for their target sites (Matthews & Nichols, 1998 ). Alternatively, a post-translational modification (phosphorylation) of a regulator or its interaction with another protein could modulate its affinity for target sites. For instance, in B. subtilis, the phosphorylation state of PRD regulators governs their DNA-binding ability (Martin-Verstraete et al., 1998
), and interaction of the pleiotropic catabolite repressor CcpA with a phosphorylated form of the phosphotransferase Hpr, Hpr Ser 46P, modulates its affinity for the catabolite-responsive elements present in the promoter regions of genes sensitive to glucose repression (Deutscher et al., 1995
). The SblA protein bears similarities to various phosphatases of the IMP family. These enzymes are usually involved in the dephosphorylation (or the phosphorylation) of small phosphorylated molecules. Considering these structural similarities, as well as the enhancement of aml expression in the absence of exogenous inducer in the sblA mutant, we propose that SblA is usually involved in the degradation of an internal inducer of aml expression or of a precursor of such an inducer. For instance, a phosphorylated glucose derivative (e.g. glucose-1-P as in E. coli; Decker et al., 1993
) might accumulate in the sblA mutant and be used as a precursor for the intracellular synthesis of an inducing maltodextrin. Alternatively, SblA might be involved in the production of a signalling molecule playing a role in catabolite repression in Streptomyces. In the glucose-grown cultures of the sblA mutant, an internal inducer of aml expression would be made (or would not be degraded) or the synthesis of a signalling molecule for catabolite repression would not occur, leading to the observed enhanced aml expression.
The identification of the SblA substrate should allow a better understanding of the biological role of this protein and of its connection with the phenomenon of catabolite repression in Streptomyces.
![]() |
ACKNOWLEDGEMENTS |
---|
![]() |
REFERENCES |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Altschul, S. F., Madden, T. L., Schaffer, A. A., Zhang, J., Zhang, Z., Miller, W. & Lipman, D. J. (1997). Gapped blast and psi-blast: a new generation of protein database search programs. Nucleic Acids Res 25, 3389-3402.
Bibb, M. J., Findlay, P. R. & Johnson, M. W. (1984). The relationship between base composition and codon usage in bacterial genes and its use for the simple and reliable identification of protein-coding sequences. Gene 30, 157-166.[Medline]
Blondelet-Rouault, M. H., Weiser, J., Lebrihi, A., Branny, P. & Pernodet, J. L. (1997). Antibiotic resistance gene cassettes derived from the omega interposon for use in E. coli and Streptomyces. Gene 190, 315-317.[Medline]
Bolivar, F., Rodriguez, R. L., Greene, P. J., Betlach, M. C., Heyneker, H. L. & Boyer, H. W. (1977). Construction and characterization of new cloning vehicles. II. A multipurpose cloning system. Gene 2, 95-113.[Medline]
Boos, W. & Shuman, H. (1998). Maltose/maltodextrin system of Escherichia coli: transport, metabolism, and regulation. Microbiol Mol Biol Rev 62, 204-229.
Decker, K., Peist, R., Reidl, J., Kossmann, M., Brand, B. & Boos, W. (1993). Maltose and maltotriose can be formed endogenously in Escherichia coli from glucose and glucose-1-phosphate independently of enzymes of the maltose system. J Bacteriol 175, 5655-5665.[Abstract]
Delic, I., Robbins, P. & Westpheling, J. (1992). Direct repeat sequences are implicated in the regulation of two Streptomyces chitinase promoters that are subject to carbon catabolite control. Proc Natl Acad Sci USA 89, 1885-1889.[Abstract]
Deutscher, J., Kuster, E., Bergstedt, U., Charrier, V. & Hillen, W. (1995). Protein kinase-dependent HPr/CcpA interaction links glycolytic activity to carbon catabolite repression in gram-positive bacteria. Mol Microbiol 15, 1049-1053.[Medline]
Hindle, Z. & Smith, C. P. (1994). Substrate induction and catabolite repression of the Streptomyces coelicolor glycerol operon are mediated through the GylR protein. Mol Microbiol 12, 737-745.[Medline]
Hopwood, D. A., Bibb, M. J., Chater, K. F. & 7 other authors (1985). Genetic Manipulation of Streptomyces: a Laboratory Manual. Norwich: John Innes Foundation.
Ikeda, H., Seno, E. T., Bruton, C. J. & Chater, K. F. (1984). Genetic mapping, cloning and physiological aspects of the glucose kinase gene of Streptomyces coelicolor. Mol Gen Genet 196, 501-507.[Medline]
Janssen, G. R. & Bibb, M. J. (1985). Derivatives of pUC18 that have BglII sites flanking a modified multiple cloning site and that retain the ability to identify recombinant clones by visual screening of Escherichia coli colonies. Gene 124, 133-134.
Jucker, F. M., Heus, H. A., Yip, P. F., Moors, E. H. & Pardi, A. (1996). A network of heterogeneous hydrogen bonds in GNRA tetraloops. J Mol Biol 264, 968-980.[Medline]
Klein, B., Foreman, J. A. & Searcy, R. L. (1969). The synthesis and utilization of Cibachron Blue-amylose: a new chromogenic substrate for determination of amylase activity. Anal Biochem 31, 412-425.[Medline]
Leblond, P., Francou, F. X., Simonet, J. M. & Decaris, B. (1990). Pulsed-field gel electrophoresis analysis of the genome of Streptomyces ambofaciens strains. FEMS Microbiol Lett 60, 79-88.[Medline]
Leblond, P., Redenbach, M. & Cullum, J. (1993). Physical map of the Streptomyces lividans 66 genome and comparison with that of the related strain Streptomyces coelicolor A3(2). J Bacteriol 175, 3422-3429.[Abstract]
Martin-Verstraete, I., Charrier, V., Stulke, J., Galinier, A., Erni, B., Rapoport, G. & Deutscher, J. (1998). Antagonistic effects of dual PTS-catalysed phosphorylation on the Bacillus subtilis transcriptional activator LevR. Mol Microbiol 28, 293-303.[Medline]
Matsuhisa, A., Suzuki, N., Noda, T. & Shiba, K. (1995). Inositol monophosphatase activity from the Escherichia coli suhB gene product. J Bacteriol 177, 200-205.[Abstract]
Matthews, K. S. & Nichols, J. C. (1998). Lactose repressor protein: functional properties and structure. Prog Nucleic Acid Res Mol Biol 58, 127-164.[Medline]
Murray, M. G. (1986). Use of sodium trichloracetate and mung bean nuclease to increase sensitivity and precision during transcript mapping. Anal Biochem 158, 165-170.[Medline]
Muth, G., Nussbaumer, B., Wohlleben, W. & Pühler, A. (1989). A vector system with temperature-sensitive replication for gene disruption and mutational cloning in streptomycetes. Mol Gen Genet 219, 341-348.
Neuwald, A. F., York, J. D. & Majerus, P. W. (1991). Diverse proteins homologous to inositol monophosphatase. FEBS Lett 294, 16-18.[Medline]
Nguyen, J. (1999). The regulatory protein Reg1 of Streptomyces lividans binds the promoter region of several genes repressed by glucose. FEMS Microbiol Lett 175, 51-58.
Nguyen, J., Francou, F., Virolle, M. J. & Guerineau, M. (1997). Amylase and chitinase genes in Streptomyces lividans are regulated by reg1, a pleiotropic regulatory gene. J Bacteriol 179, 6383-6390.[Abstract]
Ni, X. & Westpheling, J. (1997). Direct repeat sequences in the Streptomyces chitinase-63 promoter direct both glucose repression and chitin induction. Proc Natl Acad Sci USA 94, 13116-13121.
Parish, T., Liu, J., Nikaido, H. & Stoker, N. G. (1997). A Mycobacterium smegmatis mutant with a defective inositol monophosphatase phosphatase gene homolog has altered cell envelope permeability. J Bacteriol 179, 7827-7833.[Abstract]
Pridham, T. G., Anderson, P., Foley, C., Lindenfelser, L. A., Hesseltine, C. W. & Benedict, R. C. (1957). A selection media for maintenance and taxonomic study of Streptomyces. Antibiot Annu 947953.
Redenbach, M., Kieser, H. M., Denapaite, D., Eichner, A., Cullum, J., Kinashi, H. & Hopwood, D. A. (1996). A set of ordered cosmids and a detailed genetic and physical map for the 8 Mb Streptomyces coelicolor A3(2) chromosome. Mol Microbiol 21, 77-96.[Medline]
Saier, M. H.Jr, Chauvaux, S., Deutscher, J., Reizer, J. & Ye, J. J. (1995). Protein phosphorylation and regulation of carbon metabolism in Gram-negative versus Gram-positive bacteria. Trends Biochem Sci 20, 267-271.[Medline]
Sambrook, J., Fritsch, E. F. & Maniatis, T. (1989). Molecular Cloning: a Laboratory Manual, 2nd edn. Cold Spring Harbor, NY: Cold Spring Harbor Laboratory.
Sanger, F., Nicklen, S. & Coulson, A. R. (1977). DNA sequencing with chain-terminating inhibitors. Proc Natl Acad Sci USA 74, 5463-5467.[Abstract]
Solenberg, P. J. & Baltz, R. H. (1991). Transposition of Tn5096 and other IS493 derivatives in Streptomyces griseofuscus. J Bacteriol 173, 1096-1104.[Medline]
Solenberg, P. J., Burgett, S. G. & Murray, M. G. (1989). Method for selection of transposable DNA and characterization of a new insertion sequence, IS493, from Streptomyces lividans. J Bacteriol 171, 4807-4813.[Medline]
Strauch, E., Takano, E., Baylis, H. A. & Bibb, M. J. (1991). The stringent response in Streptomyces coelicolor A3(2). Mol Microbiol 5, 289-298.[Medline]
Strohl, W. R. (1992). Compilation and analysis of DNA sequences associated with apparent streptomycete promoters. Nucleic Acids Res 20, 961-974.[Abstract]
Stulke, J., Arnaud, M., Rapoport, G. & Martin-Verstraete, I. (1998). PRD a protein domain involved in PTS-dependent induction and carbon catabolite repression of catabolic operons in bacteria. Mol Microbiol 28, 865-874.[Medline]
Takano, E., Gramajo, H. C., Strauch, E., Andres, N., White, J. & Bibb, M. J. (1992). Transcriptional regulation of the redD transcriptional activator gene accounts for growth-phase-dependent production of the antibiotic undecylprodigiosin in Streptomyces coelicolor A3(2). Mol Microbiol 6, 2797-2804.[Medline]
Tercero, J. A., Espinosa, J. C., Lacalle, R. A. & Jimenez, A. (1996). The biosynthetic pathway of the aminonucleoside antibiotic puromycin, as deduced from the molecular analysis of the pur cluster of Streptomyces alboniger. J Biol Chem 271, 1579-1590.
Virolle, M.-J. & Bibb, M. J. (1988). Cloning, characterization and regulation of an alpha-amylase gene from Streptomyces limosus. Mol Microbiol 2, 197-208.[Medline]
Virolle, M.-J. & Gagnat, J. (1994). Sequences involved in growth-phase-dependent expression and glucose repression of a Streptomyces -amylase gene. Microbiology 140, 1059-1067.[Abstract]
Virolle, M.-J., Morris, V. J. & Bibb, M. J. (1990). A simple and reliable turbidimetric and kinetic assay for alpha-amylase that is readily applied to culture supernatants and cell extracts. J Ind Microbiol 5, 295-302.
Volff, J. N., Eichenseer, C., Viell, P., Piendl, W. & Altenbuchner, J. (1996). Nucleotide sequence and role in DNA amplification of the direct repeats composing the amplifiable element AUD1 of Streptomyces lividans. Mol Microbiol 21, 1037-1047.[Medline]
van Wezel, G. P., White, J., Young, P., Postma, P. W. & Bibb, M. J. (1997). Substrate induction and glucose repression of maltose utilization by Streptomyces coelicolor A3(2) is controlled by malR, a member of the lacI-galR family of regulatory genes. Mol Microbiol23, 537-549.[Medline]
Williams, S. T., Goodfellow, M., Alderson, G., Wellington, E. M., Sneath, P. H. & Sackin, M. J. (1983). Numerical classification of Streptomyces and related genera. J Gen Microbiol 129, 1743-1813.[Medline]
Yano, R., Nagai, H., Shiba, K. & Yura, T. (1990). A mutation that enhances synthesis of sigma 32 and suppresses temperature-sensitive growth of the rpoH15 mutant of Escherichia coli. J Bacteriol 172, 2124-2130.[Medline]
Received 5 February 1999;
revised 19 May 1999;
accepted 25 May 1999.
HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
INT J SYST EVOL MICROBIOL | MICROBIOLOGY | J GEN VIROL |
J MED MICROBIOL | ALL SGM JOURNALS |