CebR as a Master Regulator for Cellulose/Cellooligosaccharide Catabolism Affects Morphological Development in
            <i>Streptomyces griseus</i>

Marushima, Kazuya; Ohnishi, Yasuo; Horinouchi, Sueharu

doi:10.1128/jb.00703-09

Cited by 38 publications

(62 citation statements)

References 49 publications

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“…The most common regulatory mechanism for bacterial cellulolytic systems involves a repressor. CebR is a classic repressor of several operons of the Streptomyces griseus cellulolytic system that responds to cellodextrins (11). The cellulase system of Thermobifida fusca is transcriptionally regulated by cellobiose induction mediated through CelR (15,22).…”

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confidence: 99%

Complex Expression of the Cellulolytic Transcriptome of Saccharophagus degradans

Zhang

Hutcheson

2011

Appl Environ Microbiol

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Saccharophagus degradans is an aerobic marine bacterium that can degrade cellulose by the induced expression of an unusual cellulolytic system composed of multiple endoglucanases and glucosidases. To understand the regulation of the cellulolytic system, transcript levels for the genes predicted to contribute to the cellulolytic system were monitored by quantitative real-time PCR (qRT-PCR) during the transition to growth on cellulose. Four glucanases of the cellulolytic system exhibited basal expression during growth on glucose. All but one of the predicted cellulolytic system genes were induced strongly during growth on Avicel, with three patterns of expression observed. One group showed increased expression (up to 6-fold) within 4 h of the nutritional shift, with the relative expression remaining constant over the next 22 h. A second group of genes was strongly induced between 4 and 10 h after nutritional transfer, with relative expression declining thereafter. The third group of genes was slowly induced and was expressed maximally after 24 h. Cellodextrins and cellobiose, products of the predicted basally expressed endoglucanases, stimulated expression of representative cellulase genes. A model is proposed by which the activity of basally expressed endoglucanases releases cellodextrins from Avicel that are then perceived and transduced to initiate transcription of each of the regulated cellulolytic system genes forming an expression pattern.

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confidence: 99%

Complex Expression of the Cellulolytic Transcriptome of Saccharophagus degradans

Zhang

Hutcheson

2011

Appl Environ Microbiol

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“…3). A similar regulation of a LacI/GalR family regulator, namely, transcription from two independent promoters, an autoregulated promoter and another constitutive one, has also been reported in Streptomyces griseus CebR, a regulator of cellulose/cello-oligosaccharide catabolism (36).…”

Section: Discussionmentioning

confidence: 94%

AraR, an l -Arabinose-Responsive Transcriptional Regulator in Corynebacterium glutamicum ATCC 31831, Exerts Different Degrees of Repression Depending on the Location of Its Binding Sites within the Three Target Promoter Regions

2015

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In Corynebacterium glutamicum ATCC 31831, a LacI-type transcriptional regulator AraR, represses the expression of L-arabinose catabolism (araBDA), uptake (araE), and the regulator (araR) genes clustered on the chromosome. AraR binds to three sites: one (BS B ) between the divergent operons (araBDA and galM-araR) and two (BS E1 and BS E2 ) upstream of araE. L-Arabinose acts as an inducer of the AraR-mediated regulation. Here, we examined the roles of these AraR-binding sites in the expression of the AraR regulon. BS B mutation resulted in derepression of both araBDA and galM-araR operons. The effects of BS E1 and/or BS E2 mutation on araE expression revealed that the two sites independently function as the cis elements, but BS E1 plays the primary role. However, AraR was shown to bind to these sites with almost the same affinity in vitro. Taken together, the expression of araBDA and araE is strongly repressed by binding of AraR to a single site immediately downstream of the respective transcriptional start sites, whereas the binding site overlapping the ؊10 or ؊35 region of the galM-araR and araE promoters is less effective in repression. Furthermore, downregulation of araBDA and araE dependent on L-arabinose catabolism observed in the BS B mutant and the AraR-independent araR promoter identified within galM-araR add complexity to regulation of the AraR regulon derepressed by L-arabinose. IMPORTANCECorynebacterium glutamicum has a long history as an industrial workhorse for large-scale production of amino acids. An important aspect of industrial microorganisms is the utilization of the broad range of sugars for cell growth and production process. Most C. glutamicum strains are unable to use a pentose sugar L-arabinose as a carbon source. However, genes for L-arabinose utilization and its regulation have been recently identified in C. glutamicum ATCC 31831. This study elucidates the roles of the multiple binding sites of the transcriptional repressor AraR in the derepression by L-arabinose and thereby highlights the complex regulatory feedback loops in combination with L-arabinose catabolism-dependent repression of the AraR regulon in an AraR-independent manner. L ignocellulosic biomass from agricultural and agro-industrial residues represents one of the important renewable resources expected to be used for the industrial production of biofuels and biochemicals (1, 2). However, significant amounts of pentose sugars derived from its hemicellulose component are one major technical hurdle in the use for economically feasible bioprocesses. These sugars, such as D-xylose and L-arabinose, are not efficiently utilized by conventional and industrial microorganisms, and improvement of the pentose sugar metabolic pathways by genetic engineering is often limited by preferential utilization of a most abundant and favorable hexose sugar, D-glucose, in lignocellulosic biomass (3).Corynebacterium glutamicum is a Gram-positive actinobacterium with a high GϩC content in its genomic DNA. It has a long history as an industri...

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“…It was strongly suggested that these gene products are secreted outside the cells as mature, active enzymes by digestion of the N-terminal signal peptides. In S. griseus, CebR, a regulatory protein for cellobiose/ cellooligosaccharide catabolism, binds to the CebR box, a 14-bp inverted repeat sequence (TGGGAGCGCTCCCT), to repress the transcription of the genes related to the catabolism [32]. The CebR box sequences were found upstream of the cel9A C , cel5A M , and cel12B M genes, suggesting that expression of these genes are regulated by CebR to be inducible by cellobiose in the C42 and M178 strains.…”

Section: Cloning and Nucleotide Sequencing Of Secretorymentioning

confidence: 99%

Cloning and Sequence Analysis of the Cellulase Genes Isolated from Two Cellulolytic Streptomycetes and Their Heterologous Expression in <i>Streptomyces lividans </i>

Tomotsune

Kasuga

Tsuchida

et al. 2014

Int.J.Soc.Mater.Eng.Resour.

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Cellulosic biomass, such as wood waste and rice straw, remains unexploited despite the high content of cellulose. Streptomycetes are producers of industrially important antibiotics and most of the antibioticproducing strains are unable to utilize cellulose. We have, therefore, aimed to breed streptomycetes that produce antibiotics from cellulosic biomass. Two cellulolytic streptomycetes, i.e. Streptomyces thermocarboxydus C42 and Streptomyces argenteolus M178, were selected on the basis of carboxymethyl cellulose (CMC)-degrading activity from approximately 1,000 soil-isolated streptomycetes. Shotgun cloning experiments of cellulase genes from these genomic DNAs were performed in Streptomyces lividans as a host to find putative four cellulase genes, i.e. cel9A C and cel5A C from the C42 strain and cel5A M and cel12B M from the M178 strain. The transformants of S. lividans harboring the four genes subcloned in an expression plasmid showed secreted CMC-degrading cellulase (CMCase) activities, thus demonstrating successful cloning and heterologous expression of the cellulase genes from the cellulolytic streptomycetes. 2.2 CMC assay and Measurement of CMC-degrading cellulase (CMCase) activity Streptomyces isolates were cultivated in 2 ml of GPY and CPY liquid media at 30˚C in a test tube containing a glass bead on a reciprocal shaker at 130 strokes/min for 3 to 4 days. A portion (50 µl) of the supernatant of culture broth was placed in wells (6 mm diameter and 5 mm depth) on 1.5% (w/v) agar plates containing 0.5% (w/v) CMC sodium salt and the plates were incubated at 37˚C for 12 hours for CMC degradation [14]. Staining of the plates with 0.1% (w/v) Congo red solution and the following destaining with 1 M NaCl visualized CMC-digested clear zones formed around the wells by the diffusion of CMCase. On the other hand, the CMCase activity was measured using CMC as the substrate as described by Okada et al. [15] with some modifications. The supernatant (20 µL) of the Streptomyces culture was mixed with 80 µL of 1.25% CMC solution in 50 mM acetate buffer (pH 6.0) for incubation at 37˚C for 60 min, and the reducing sugar released was determined by the 3,5-dinitrosalicylic acid method [16]. The experiment was conducted in triplicate. One unit of CMCase activity was defined as the amount of enzyme releasing 1 µmol of glucose equivalent per minute.2.3 DNA manipulation DNA manipulations using E. coli as a host were carried out as described by Sambrook et al. [18]. DNA manipulations in Streptomyces cells were conducted as described in a manual by Kieser et al. [16]. Enzymes and kits for DNA recombination techniques were purchased from Takara Bio Inc. and Toyobo Co. Ltd., and used according to the manufacturers' instructions. Polymerase chain reaction (PCR) was conducted using an iCycler thermal cycler (Bio-Rad Laboratories Inc.) with Takara LA Taq with GC buffer (Takara Bio Inc.) and KOD-Plus-(Toyobo Co. Ltd.). All PCR primers used for this study were synthesized commercially (Hokkaido System Science Co. Ltd.) as listed in Table...

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CebR as a Master Regulator for Cellulose/Cellooligosaccharide Catabolism Affects Morphological Development in Streptomyces griseus

Cited by 38 publications

References 49 publications

Complex Expression of the Cellulolytic Transcriptome of Saccharophagus degradans

Complex Expression of the Cellulolytic Transcriptome of Saccharophagus degradans

AraR, an l -Arabinose-Responsive Transcriptional Regulator in Corynebacterium glutamicum ATCC 31831, Exerts Different Degrees of Repression Depending on the Location of Its Binding Sites within the Three Target Promoter Regions

Cloning and Sequence Analysis of the Cellulase Genes Isolated from Two Cellulolytic Streptomycetes and Their Heterologous Expression in <i>Streptomyces lividans </i>

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