scholarly journals Corynebacterium glutamicum Tailored for Efficient Isobutanol Production

2011 ◽  
Vol 77 (10) ◽  
pp. 3300-3310 ◽  
Author(s):  
Bastian Blombach ◽  
Tanja Riester ◽  
Stefan Wieschalka ◽  
Christian Ziert ◽  
Jung-Won Youn ◽  
...  
Keyword(s):  
Alcohol Dehydrogenase ◽  
Corynebacterium Glutamicum ◽  
Malic Enzyme ◽  
Pyruvate Dehydrogenase Complex ◽  
Specific Yield ◽  
Acetohydroxyacid Synthase ◽  
Content Type ◽  
Production Phase ◽  
Genes Encoding ◽  
Alcohol Dehydrogenase 2

ABSTRACTWe recently engineeredCorynebacterium glutamicumfor aerobic production of 2-ketoisovalerate by inactivation of the pyruvate dehydrogenase complex, pyruvate:quinone oxidoreductase, transaminase B, and additional overexpression of theilvBNCDgenes, encoding acetohydroxyacid synthase, acetohydroxyacid isomeroreductase, and dihydroxyacid dehydratase. Based on this strain, we engineeredC. glutamicumfor the production of isobutanol from glucose under oxygen deprivation conditions by inactivation ofl-lactate and malate dehydrogenases, implementation of ketoacid decarboxylase fromLactococcus lactis, alcohol dehydrogenase 2 (ADH2) fromSaccharomyces cerevisiae, and expression of thepntABtranshydrogenase genes fromEscherichia coli. The resulting strain produced isobutanol with a substrate-specific yield (YP/S) of 0.60 ± 0.02 mol per mol of glucose. Interestingly, a chromosomally encoded alcohol dehydrogenase rather than the plasmid-encoded ADH2 fromS. cerevisiaewas involved in isobutanol formation withC. glutamicum, and overexpression of the correspondingadhAgene increased the YP/Sto 0.77 ± 0.01 mol of isobutanol per mol of glucose. Inactivation of the malic enzyme significantly reduced the YP/S, indicating that the metabolic cycle consisting of pyruvate and/or phosphoenolpyruvate carboxylase, malate dehydrogenase, and malic enzyme is responsible for the conversion of NADH+H+to NADPH+H+. In fed-batch fermentations with an aerobic growth phase and an oxygen-depleted production phase, the most promising strain,C. glutamicumΔaceEΔpqoΔilvEΔldhAΔmdh(pJC4ilvBNCD-pntAB)(pBB1kivd-adhA), produced about 175 mM isobutanol, with a volumetric productivity of 4.4 mM h−1, and showed an overall YP/Sof about 0.48 mol per mol of glucose in the production phase.

scholarly journals Platform Engineering of Corynebacterium glutamicum with Reduced Pyruvate Dehydrogenase Complex Activity for Improved Production of l-Lysine, l-Valine, and 2-Ketoisovalerate

2013 ◽  
Vol 79 (18) ◽  
pp. 5566-5575 ◽  
Author(s):  
Jens Buchholz ◽  
Andreas Schwentner ◽  
Britta Brunnenkan ◽  
Christina Gabris ◽  
Simon Grimm ◽  
...  
Keyword(s):  
Corynebacterium Glutamicum ◽  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Complex ◽  
Fed Batch ◽  
Complex Activity ◽  
Gene Encoding ◽  
Content Type ◽  
Genes Encoding ◽  
Cell Densities ◽  
Dehydrogenase Complex

ABSTRACTExchange of the nativeCorynebacterium glutamicumpromoter of theaceEgene, encoding the E1p subunit of the pyruvate dehydrogenase complex (PDHC), with mutateddapApromoter variants led to a series ofC. glutamicumstrains with gradually reduced growth rates and PDHC activities. Upon overexpression of thel-valine biosynthetic genesilvBNCE, all strains producedl-valine. Among these strains,C. glutamicum aceEA16 (pJC4ilvBNCE) showed the highest biomass and product yields, and thus it was further improved by additional deletion of thepqoandppcgenes, encoding pyruvate:quinone oxidoreductase and phosphoenolpyruvate carboxylase, respectively. In fed-batch fermentations at high cell densities,C. glutamicum aceEA16 Δpqo Δppc(pJC4ilvBNCE) produced up to 738 mM (i.e., 86.5 g/liter)l-valine with an overall yield (YP/S) of 0.36 mol per mol of glucose and a volumetric productivity (QP) of 13.6 mM per h [1.6 g/(liter × h)]. Additional inactivation of the transaminase B gene (ilvE) and overexpression ofilvBNCDinstead ofilvBNCEtransformed thel-valine-producing strain into a 2-ketoisovalerate producer, excreting up to 303 mM (35 g/liter) 2-ketoisovalerate with aYP/Sof 0.24 mol per mol of glucose and aQPof 6.9 mM per h [0.8 g/(liter × h)]. The replacement of theaceEpromoter by thedapA-A16 promoter in the twoC. glutamicuml-lysine producers DM1800 and DM1933 improved the production by 100% and 44%, respectively. These results demonstrate thatC. glutamicumstrains with reduced PDHC activity are an excellent platform for the production of pyruvate-derived products.

scholarly journals Metabolic Engineering of Corynebacterium glutamicum for 2-Ketoisovalerate Production

2010 ◽  
Vol 76 (24) ◽  
pp. 8053-8061 ◽  
Author(s):  
Felix S. Krause ◽  
Bastian Blombach ◽  
Bernhard J. Eikmanns
Keyword(s):  
Corynebacterium Glutamicum ◽  
Competitive Inhibition ◽  
Pyruvate Dehydrogenase Complex ◽  
Product Yield ◽  
Acetohydroxyacid Synthase ◽  
Gene Encoding ◽  
Keto Acids ◽  
Genes Encoding ◽  
Cell Densities ◽  
Branched Chain

ABSTRACT 2-Ketoisovalerate is used as a therapeutic agent, and a 2-ketoisovalerate-producing organism may serve as a platform for products deriving from this 2-keto acid. We engineered the wild type of Corynebacterium glutamicum for the growth-decoupled production of 2-ketoisovalerate from glucose by deletion of the aceE gene encoding the E1p subunit of the pyruvate dehydrogenase complex, deletion of the transaminase B gene ilvE, and additional overexpression of the ilvBNCD genes, encoding the l-valine biosynthetic enzymes acetohydroxyacid synthase (AHAS), acetohydroxyacid isomeroreductase, and dihydroxyacid dehydratase. 2-Ketoisovalerate production was further improved by deletion of the pyruvate:quinone oxidoreductase gene pqo. In fed-batch fermentations at high cell densities, the newly constructed strains produced up to 188 ± 28 mM (21.8 ± 3.2 g liter−1) 2-ketoisovalerate and showed a product yield of about 0.47 ± 0.05 mol per mol (0.3 ± 0.03 g per g) of glucose and a volumetric productivity of about 4.6 ± 0.6 mM (0.53 ± 0.07 g liter−1) 2-ketoisovalerate per h in the overall production phase. In studying the influence of the three branched-chain 2-keto acids 2-ketoisovalerate, 2-ketoisocaproate, and 2-keto-3-methylvalerate on the AHAS activity, we observed a competitive inhibition of the AHAS enzyme by 2-ketoisovalerate.

scholarly journals l-Valine Production with Pyruvate Dehydrogenase Complex-Deficient Corynebacterium glutamicum

2007 ◽  
Vol 73 (7) ◽  
pp. 2079-2084 ◽  
Author(s):  
Bastian Blombach ◽  
Mark E. Schreiner ◽  
Jiří Holátko ◽  
Tobias Bartek ◽  
Marco Oldiges ◽  
...  
Keyword(s):  
Corynebacterium Glutamicum ◽  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Complex ◽  
Maximum Yield ◽  
Cellular Growth ◽  
Acetohydroxyacid Synthase ◽  
Gene Encoding ◽  
Genes Encoding ◽  
Cell Densities ◽  
Dehydrogenase Complex

ABSTRACT Corynebacterium glutamicum was engineered for the production of l-valine from glucose by deletion of the aceE gene encoding the E1p enzyme of the pyruvate dehydrogenase complex and additional overexpression of the ilvBNCE genes encoding the l-valine biosynthetic enzymes acetohydroxyacid synthase, isomeroreductase, and transaminase B. In the absence of cellular growth, C. glutamicum ΔaceE showed a relatively high intracellular concentration of pyruvate (25.9 mM) and produced significant amounts of pyruvate, l-alanine, and l-valine from glucose as the sole carbon source. Lactate or acetate was not formed. Plasmid-bound overexpression of ilvBNCE in C. glutamicum ΔaceE resulted in an approximately 10-fold-lower intracellular pyruvate concentration (2.3 mM) and a shift of the extracellular product pattern from pyruvate and l-alanine towards l-valine. In fed-batch fermentations at high cell densities and an excess of glucose, C. glutamicum ΔaceE(pJC4ilvBNCE) produced up to 210 mM l-valine with a volumetric productivity of 10.0 mM h−1 (1.17 g l−1 h−1) and a maximum yield of about 0.6 mol per mol (0.4 g per g) of glucose.

scholarly journals Malic Enzyme and Malolactic Enzyme Pathways Are Functionally Linked but Independently Regulated in Lactobacillus casei BL23

2013 ◽  
Vol 79 (18) ◽  
pp. 5509-5518 ◽  
Author(s):  
José María Landete ◽  
Sergi Ferrer ◽  
Vicente Monedero ◽  
Manuel Zúñiga
Keyword(s):  
Carbon Source ◽  
Gene Cluster ◽  
Malic Enzyme ◽  
Lactobacillus Casei ◽  
Growth Defect ◽  
Two Component System ◽  
Content Type ◽  
Malolactic Enzyme ◽  
Genes Encoding ◽  
Malate Metabolism

ABSTRACTLactobacillus caseiis the only lactic acid bacterium in which two pathways forl-malate degradation have been described: the malolactic enzyme (MLE) and the malic enzyme (ME) pathways. Whereas the ME pathway enablesL. caseito grow onl-malate, MLE does not support growth. Themlegene cluster consists of three genes encoding MLE (mleS), the putativel-malate transporter MleT, and the putative regulator MleR. Themaegene cluster consists of four genes encoding ME (maeE), the putative transporter MaeP, and the two-component system MaeKR. Since both pathways compete for the same substrate, we sought to determine whether they are coordinately regulated and their role inl-malate utilization as a carbon source. Transcriptional analyses revealed that themleandmaegenes are independently regulated and showed that MleR acts as an activator and requires internalization ofl-malate to induce the expression ofmlegenes. Notwithstanding, bothl-malate transporters were required for maximall-malate uptake, although only anmleTmutation caused a growth defect onl-malate, indicating its crucial role inl-malate metabolism. However, inactivation of MLE resulted in higher growth rates and higher final optical densities onl-malate. The limited growth onl-malate of the wild-type strain was correlated to a rapid degradation of the availablel-malate tol-lactate, which cannot be further metabolized. Taken together, our results indicate thatL. caseil-malate metabolism is not optimized for utilization ofl-malate as a carbon source but for deacidification of the medium by conversion ofl-malate intol-lactate via MLE.

scholarly journals Overexpression of Genes Encoding Glycolytic Enzymes in Corynebacterium glutamicum Enhances Glucose Metabolism and Alanine Production under Oxygen Deprivation Conditions

2012 ◽  
Vol 78 (12) ◽  
pp. 4447-4457 ◽  
Author(s):  
Shogo Yamamoto ◽  
Wataru Gunji ◽  
Hiroaki Suzuki ◽  
Hiroshi Toda ◽  
Masako Suda ◽  
...  
Keyword(s):  
Glucose Metabolism ◽  
Corynebacterium Glutamicum ◽  
Glucose Consumption ◽  
Glycolytic Enzyme ◽  
Oxygen Deprivation ◽  
Glycolytic Enzymes ◽  
Content Type ◽  
Extracellular Metabolites ◽  
High Copy Number Plasmid ◽  
Genes Encoding

ABSTRACTWe previously reported thatCorynebacterium glutamicumstrain ΔldhAΔppc+alaD+gapA, overexpressing glyceraldehyde-3-phosphate dehydrogenase-encodinggapA, shows significantly improved glucose consumption and alanine formation under oxygen deprivation conditions (T. Jojima, M. Fujii, E. Mori, M. Inui, and H. Yukawa, Appl. Microbiol. Biotechnol. 87:159–165, 2010). In this study, we employ stepwise overexpression and chromosomal integration of a total of four genes encoding glycolytic enzymes (herein referred to as glycolytic genes) to demonstrate further successive improvements inC. glutamicumglucose metabolism under oxygen deprivation. In addition togapA, overexpressing pyruvate kinase-encodingpykand phosphofructokinase-encodingpfkenabled strain GLY2/pCRD500 to realize respective 13% and 20% improved rates of glucose consumption and alanine formation compared to GLY1/pCRD500. Subsequent overexpression of glucose-6-phosphate isomerase-encodinggpiin strain GLY3/pCRD500 further improved its glucose metabolism. Notably, both alanine productivity and yield increased after each overexpression step. After 48 h of incubation, GLY3/pCRD500 produced 2,430 mM alanine at a yield of 91.8%. This was 6.4-fold higher productivity than that of the wild-type strain. Intracellular metabolite analysis showed thatgapAoverexpression led to a decreased concentration of metabolites upstream of glyceraldehyde-3-phosphate dehydrogenase, suggesting that the overexpression resolved a bottleneck in glycolysis. Changing ratios of the extracellular metabolites by overexpression of glycolytic genes resulted in reduction of the intracellular NADH/NAD+ratio, which also plays an important role on the improvement of glucose consumption. Enhanced alanine dehydrogenase activity using a high-copy-number plasmid further accelerated the overall alanine productivity. Increase in glycolytic enzyme activities is a promising approach to make drastic progress in growth-arrested bioprocesses.

scholarly journals E1 Enzyme of the Pyruvate Dehydrogenase Complex in Corynebacterium glutamicum: Molecular Analysis of the Gene and Phylogenetic Aspects

2005 ◽  
Vol 187 (17) ◽  
pp. 6005-6018 ◽  
Author(s):  
Mark E. Schreiner ◽  
Diana Fiur ◽  
Jiří Holátko ◽  
Miroslav Pátek ◽  
Bernhard J. Eikmanns
Keyword(s):  
Corynebacterium Glutamicum ◽  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Complex ◽  
Transcriptional Analysis ◽  
Oxidative Decarboxylation ◽  
Gene Encoding ◽  
Mutant Sequence ◽  
Genes Encoding ◽  
Translational Start ◽  
Dehydrogenase Complex

ABSTRACT The E1p enzyme is an essential part of the pyruvate dehydrogenase complex (PDHC) and catalyzes the oxidative decarboxylation of pyruvate with concomitant acetylation of the E2p enzyme within the complex. We analyzed the Corynebacterium glutamicum aceE gene, encoding the E1p enzyme, and constructed and characterized an E1p-deficient mutant. Sequence analysis of the C. glutamicum aceE gene and adjacent regions revealed that aceE is not flanked by genes encoding other enzymes of the PDHC. Transcriptional analysis revealed that aceE from C. glutamicum is monocistronic and that its transcription is initiated 121 nucleotides upstream of the translational start site. Inactivation of the chromosomal aceE gene led to the inability to grow on glucose and to the absence of PDHC and E1p activities, indicating that only a single E1p enzyme is present in C. glutamicum and that the PDHC is essential for the growth of this organism on carbohydrate substrates. Surprisingly, the E1p enzyme of C. glutamicum showed up to 51% identity to homodimeric E1p proteins from gram-negative bacteria but no similarity to E1 α- or β-subunits of heterotetrameric E1p enzymes which are generally assumed to be typical for gram-positives. To investigate the distribution of E1p enzymes in bacteria, we compiled and analyzed the phylogeny of 46 homodimeric E1p proteins and of 58 α-subunits of heterotetrameric E1p proteins deposited in public databases. The results revealed that the distribution of homodimeric and heterotetrameric E1p subunits in bacteria is not in accordance with the rRNA-based phylogeny of bacteria and is more heterogeneous than previously assumed.

scholarly journals Impact of CO2/HCO3– Availability on Anaplerotic Flux in Pyruvate Dehydrogenase Complex-Deficient Corynebacterium glutamicum Strains

2019 ◽  
Vol 201 (20) ◽  
Author(s):  
Aileen Krüger ◽  
Johanna Wiechert ◽  
Cornelia Gätgens ◽  
Tino Polen ◽  
Regina Mahr ◽  
...  
Keyword(s):  
Corynebacterium Glutamicum ◽  
Pyruvate Dehydrogenase ◽  
Pyruvate Carboxylase ◽  
Metabolic Flux ◽  
Pyruvate Dehydrogenase Complex ◽  
Lag Phase ◽  
Production Rates ◽  
Content Type ◽  
The Impact ◽  
Dehydrogenase Complex

ABSTRACT The pyruvate dehydrogenase complex (PDHC) catalyzes the oxidative decarboxylation of pyruvate, yielding acetyl coenzyme A (acetyl-CoA) and CO2. The PDHC-deficient Corynebacterium glutamicum ΔaceE strain therefore lacks an important decarboxylation step in its central metabolism. Additional inactivation of pyc, encoding pyruvate carboxylase, resulted in a >15-h lag phase in the presence of glucose, while no growth defect was observed on gluconeogenetic substrates, such as acetate. Growth was successfully restored by deletion of ptsG, encoding the glucose-specific permease of the phosphotransferase system (PTS), thereby linking the observed phenotype to the increased sensitivity of the ΔaceE Δpyc strain to glucose catabolism. In this work, the ΔaceE Δpyc strain was used to systematically study the impact of perturbations of the intracellular CO2/HCO3– pool on growth and anaplerotic flux. Remarkably, all measures leading to enhanced CO2/HCO3– levels, such as external addition of HCO3–, increasing the pH, or rerouting metabolic flux via the pentose phosphate pathway, at least partially eliminated the lag phase of the ΔaceE Δpyc strain on glucose medium. In accordance with these results, inactivation of the urease enzyme, lowering the intracellular CO2/HCO3– pool, led to an even longer lag phase, accompanied by the excretion of l-valine and l-alanine. Transcriptome analysis, as well as an adaptive laboratory evolution experiment with the ΔaceE Δpyc strain, revealed the reduction of glucose uptake as a key adaptive measure to enhance growth on glucose-acetate mixtures. Taken together, our results highlight the significant impact of the intracellular CO2/HCO3– pool on metabolic flux distribution, which becomes especially evident in engineered strains exhibiting low endogenous CO2 production rates, as exemplified by PDHC-deficient strains. IMPORTANCE CO2 is a ubiquitous product of cellular metabolism and an essential substrate for carboxylation reactions. The pyruvate dehydrogenase complex (PDHC) catalyzes a central metabolic reaction contributing to the intracellular CO2/HCO3– pool in many organisms. In this study, we used a PDHC-deficient strain of Corynebacterium glutamicum, which additionally lacked pyruvate carboxylase (ΔaceE Δpyc). This strain featured a >15-h lag phase during growth on glucose-acetate mixtures. We used this strain to systematically assess the impact of alterations in the intracellular CO2/HCO3– pool on growth in glucose-acetate medium. Remarkably, all measures enhancing CO2/HCO3– levels successfully restored growth. These results emphasize the strong impact of the intracellular CO2/HCO3– pool on metabolic flux, especially in strains exhibiting low endogenous CO2 production rates.

scholarly journals Streptococcus pyogenes Malate Degradation Pathway Links pH Regulation and Virulence

2015 ◽  
Vol 83 (3) ◽  
pp. 1162-1171 ◽  
Author(s):  
Elyse Paluscio ◽  
Michael G. Caparon
Keyword(s):  
Carbon Source ◽  
Streptococcus Pyogenes ◽  
Malic Enzyme ◽  
Ph Regulation ◽  
Carbon Sources ◽  
Degradation Pathway ◽  
Content Type ◽  
Ph Response ◽  
Expression Of Genes ◽  
Genes Encoding

The ability ofStreptococcus pyogenesto infect different niches within its human host most likely relies on its ability to utilize alternative carbon sources. In examining this question, we discovered that all sequencedS. pyogenesstrains possess the genes for the malic enzyme (ME) pathway, which allows malate to be used as a supplemental carbon source for growth. ME is comprised of four genes in two adjacent operons, with the regulatory two-component MaeKR required for expression of genes encoding a malate permease (maeP) and malic enzyme (maeE). Analysis of transcription indicated that expression ofmaePandmaeEis induced by both malate and low pH, and induction in response to both cues is dependent on the MaeK sensor kinase. Furthermore, bothmaePEandmaeKRare repressed by glucose, which occurs via a CcpA-independent mechanism. Additionally, malate utilization requires the PTS transporter EI enzyme (PtsI), as a PtsI–mutant fails to express the ME genes and is unable to utilize malate. Virulence of selected ME mutants was assessed in a murine model of soft tissue infection. MaeP–, MaeK–, and MaeR–mutants were attenuated for virulence, whereas a MaeE–mutant showed enhanced virulence compared to that of the wild type. Taken together, these data show that ME contributes toS. pyogenes' carbon source repertory, that malate utilization is a highly regulated process, and that a single regulator controls ME expression in response to diverse signals. Furthermore, malate uptake and utilization contribute to the adaptive pH response, and ME can influence the outcome of infection.

scholarly journals Metabolic Engineering of Corynebacterium glutamicum for Methanol Metabolism

2015 ◽  
Vol 81 (6) ◽  
pp. 2215-2225 ◽  
Author(s):  
Sabrina Witthoff ◽  
Katja Schmitz ◽  
Sebastian Niedenführ ◽  
Katharina Nöh ◽  
Stephan Noack ◽  
...  
Keyword(s):  
Corynebacterium Glutamicum ◽  
Biotechnological Production ◽  
Methanol Metabolism ◽  
Initial Oxidation ◽  
Content Type ◽  
Oxidation Of Methanol ◽  
Bacillus Methanolicus ◽  
Production Processes ◽  
Starting Point ◽  
Limited Application

ABSTRACTMethanol is already an important carbon feedstock in the chemical industry, but it has found only limited application in biotechnological production processes. This can be mostly attributed to the inability of most microbial platform organisms to utilize methanol as a carbon and energy source. With the aim to turn methanol into a suitable feedstock for microbial production processes, we engineered the industrially important but nonmethylotrophic bacteriumCorynebacterium glutamicumtoward the utilization of methanol as an auxiliary carbon source in a sugar-based medium. Initial oxidation of methanol to formaldehyde was achieved by heterologous expression of a methanol dehydrogenase fromBacillus methanolicus, whereas assimilation of formaldehyde was realized by implementing the two key enzymes of the ribulose monophosphate pathway ofBacillus subtilis: 3-hexulose-6-phosphate synthase and 6-phospho-3-hexuloisomerase. The recombinantC. glutamicumstrain showed an average methanol consumption rate of 1.7 ± 0.3 mM/h (mean ± standard deviation) in a glucose-methanol medium, and the culture grew to a higher cell density than in medium without methanol. In addition, [13C]methanol-labeling experiments revealed labeling fractions of 3 to 10% in the m + 1 mass isotopomers of various intracellular metabolites. In the background of aC. glutamicumΔaldΔadhEmutant being strongly impaired in its ability to oxidize formaldehyde to CO2, the m + 1 labeling of these intermediates was increased (8 to 25%), pointing toward higher formaldehyde assimilation capabilities of this strain. The engineeredC. glutamicumstrains represent a promising starting point for the development of sugar-based biotechnological production processes using methanol as an auxiliary substrate.

scholarly journals Genes Required for Aerial Growth, Cell Division, and Chromosome Segregation Are Targets of WhiA before Sporulation in Streptomyces venezuelae

mBio ◽  
2013 ◽  
Vol 4 (5) ◽  
Author(s):  
Matthew J. Bush ◽  
Maureen J. Bibb ◽  
Govind Chandra ◽  
Kim C. Findlay ◽  
Mark J. Buttner
Keyword(s):  
Cell Division ◽  
Chromosome Segregation ◽  
Regulatory Networks ◽  
Liquid Culture ◽  
Biological Processes ◽  
Streptomyces Venezuelae ◽  
Content Type ◽  
Master Regulators ◽  
Aerial Growth ◽  
Genes Encoding

ABSTRACTWhiA is a highly unusual transcriptional regulator related to a family of eukaryotic homing endonucleases. WhiA is required for sporulation in the filamentous bacteriumStreptomyces, but WhiA homologues of unknown function are also found throughout the Gram-positive bacteria. To better understand the role of WhiA inStreptomycesdevelopment and its function as a transcription factor, we identified the WhiA regulon through a combination of chromatin immunoprecipitation-sequencing (ChIP-seq) and microarray transcriptional profiling, exploiting a new model organism for the genus,Streptomyces venezuelae, which sporulates in liquid culture. The regulon encompasses ~240 transcription units, and WhiA appears to function almost equally as an activator and as a repressor. Bioinformatic analysis of the upstream regions of the complete regulon, combined with DNase I footprinting, identified a short but highly conserved asymmetric sequence, GACAC, associated with the majority of WhiA targets. Construction of a null mutant showed thatwhiAis required for the initiation of sporulation septation and chromosome segregation inS. venezuelae, and several genes encoding key proteins of theStreptomycescell division machinery, such asftsZ,ftsW, andftsK, were found to be directly activated by WhiA during development. Several other genes encoding proteins with important roles in development were also identified as WhiA targets, including the sporulation-specific sigma factor σWhiGand the diguanylate cyclase CdgB. Cell division is tightly coordinated with the orderly arrest of apical growth in the sporogenic cell, andfilP, encoding a key component of the polarisome that directs apical growth, is a direct target for WhiA-mediated repression during sporulation.IMPORTANCESince the initial identification of the genetic loci required forStreptomycesdevelopment, all of thebldandwhidevelopmental master regulators have been cloned and characterized, and significant progress has been made toward understanding the cell biological processes that drive morphogenesis. A major challenge now is to connect the cell biological processes and the developmental master regulators by dissecting the regulatory networks that link the two. Studies of these regulatory networks have been greatly facilitated by the recent introduction ofStreptomyces venezuelaeas a new model system for the genus, a species that sporulates in liquid culture. Taking advantage ofS. venezuelae, we have characterized the regulon of genes directly under the control of one of these master regulators, WhiA. Our results implicate WhiA in the direct regulation of key steps in sporulation, including the cessation of aerial growth, the initiation of cell division, and chromosome segregation.

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