1
|
Seo SO, Janssen H, Magis A, Wang Y, Lu T, Price ND, Jin YS, Blaschek HP. Genomic, Transcriptional, and Phenotypic Analysis of the Glucose Derepressed Clostridium beijerinckii Mutant Exhibiting Acid Crash Phenotype. Biotechnol J 2017; 12. [PMID: 28762642 DOI: 10.1002/biot.201700182] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 05/07/2017] [Indexed: 01/08/2023]
Abstract
Clostridium beijerinckii is a predominant solventogenic bacterium that is used for the ABE fermentation. Various C. beijerinckii mutants are constructed for desirable phenotypes. The C. beijerinckii mutant BA105 harboring a glucose derepression phenotype was previously isolated and demonstrated the enhanced amylolytic activity in the presence of glucose. Despite its potential use, BA105 is not further characterized and utilized. Therefore, the authors investigate fermentation phenotypes of BA105 in this study. Under the typical batch fermentation conditions, BA105 consistently exhibits acid crash phenotype resulting in limited glucose uptake and cell growth. However, when the culture pH is maintained above 5.5, BA105 exhibits the increased glucose uptake and butanol production than did the wild-type. To further analyze BA105, the authors perform genome sequencing and RNA sequencing. Genome analysis identifies two SNPs unique to BA105, in the upstream region of AbrB regulator (Cbei_4885) and the ROK family glucokinase (Cbei_4895) which are involved in catabolite repression and regulation of sugar metabolism. Transcriptional analysis of BA105 reveals significant differential expression of the genes associated with the PTS sugar transport system and acid production. This study improves understanding of the acid crash phenomenon and provides the genetic basis underlying the catabolite derepression phenotype of C. beijericnkii.
Collapse
Affiliation(s)
- Seung-Oh Seo
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Holger Janssen
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | | | - Yi Wang
- Biosystems Engineering Department, Auburn University, Auburn, AL, 36849, USA
| | - Ting Lu
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.,Department of Bioengineering and Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | | | - Yong-Su Jin
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Hans P Blaschek
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.,The Integrated Bioprocessing Research Laboratory (IBRL), University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| |
Collapse
|
2
|
Biochemistry and regulatory functions of bacterial glucose kinases. Arch Biochem Biophys 2015; 577-578:1-10. [DOI: 10.1016/j.abb.2015.05.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Revised: 04/30/2015] [Accepted: 05/02/2015] [Indexed: 11/19/2022]
|
3
|
Romero-Rodríguez A, Robledo-Casados I, Sánchez S. An overview on transcriptional regulators in Streptomyces. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2015; 1849:1017-39. [PMID: 26093238 DOI: 10.1016/j.bbagrm.2015.06.007] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Revised: 06/09/2015] [Accepted: 06/12/2015] [Indexed: 12/19/2022]
Abstract
Streptomyces are Gram-positive microorganisms able to adapt and respond to different environmental conditions. It is the largest genus of Actinobacteria comprising over 900 species. During their lifetime, these microorganisms are able to differentiate, produce aerial mycelia and secondary metabolites. All of these processes are controlled by subtle and precise regulatory systems. Regulation at the transcriptional initiation level is probably the most common for metabolic adaptation in bacteria. In this mechanism, the major players are proteins named transcription factors (TFs), capable of binding DNA in order to repress or activate the transcription of specific genes. Some of the TFs exert their action just like activators or repressors, whereas others can function in both manners, depending on the target promoter. Generally, TFs achieve their effects by using one- or two-component systems, linking a specific type of environmental stimulus to a transcriptional response. After DNA sequencing, many streptomycetes have been found to have chromosomes ranging between 6 and 12Mb in size, with high GC content (around 70%). They encode for approximately 7000 to 10,000 genes, 50 to 100 pseudogenes and a large set (around 12% of the total chromosome) of regulatory genes, organized in networks, controlling gene expression in these bacteria. Among the sequenced streptomycetes reported up to now, the number of transcription factors ranges from 471 to 1101. Among these, 315 to 691 correspond to transcriptional regulators and 31 to 76 are sigma factors. The aim of this work is to give a state of the art overview on transcription factors in the genus Streptomyces.
Collapse
Affiliation(s)
- Alba Romero-Rodríguez
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México, D.F. 04510, Mexico
| | - Ivonne Robledo-Casados
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México, D.F. 04510, Mexico
| | - Sergio Sánchez
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México, D.F. 04510, Mexico.
| |
Collapse
|
4
|
Puopolo G, Masi M, Raio A, Andolfi A, Zoina A, Cimmino A, Evidente A. Insights on the susceptibility of plant pathogenic fungi to phenazine-1-carboxylic acid and its chemical derivatives. Nat Prod Res 2012; 27:956-66. [PMID: 22724439 DOI: 10.1080/14786419.2012.696257] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Pseudomonas chlororaphis subsp. aureofaciens strain M71 produced two phenazine compounds as main secondary metabolites. These metabolites were identified as phenazine-1-carboxylic acid (PCA) and 2-hydroxyphenazine (2-OH P). In this study, the spectrum of the activity of PCA and 2-OH P was evaluated against a group of crop and forestal plant pathogenic fungi by an agar plate bioassay. PCA was active against most of the tested plant pathogens, while 2-OH P slightly inhibited a few fungal species. Furthermore, four semisynthesised derivatives of PCA (phenazine-1-carboxymethyl, phenazine-1-carboxamide, phenazine-1-hydroxymethyl and phenazine-1-acetoxymethyl) were assayed for their antifungal activity against 11 phytopathogenic species. Results showed that the carboxyl group is a structural feature important for the antifungal activity of PCA. Since the activity of phenazine-1-carboxymethyl and phenazine-1-carboxamide, the two more lipophilic and reversible PCA derivatives remained substantially unaltered compared with PCA.
Collapse
Affiliation(s)
- Gerardo Puopolo
- Dipartimento di Arboricoltura, Botanica e Patologia Vegetale, Universitá di Napoli Federico II, Via Università 100, 80055 Portici, Italy
| | | | | | | | | | | | | |
Collapse
|
5
|
The role of glucose kinase in carbohydrate utilization and extracellular polysaccharide production in Xanthomonas campestris pathovar campestris. Microbiology (Reading) 2007; 153:4284-4294. [DOI: 10.1099/mic.0.2007/010538-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
|
6
|
Han B, Liu H, Hu X, Cai Y, Zheng D, Yuan Z. Molecular characterization of a glucokinase with broad hexose specificity from Bacillus sphaericus strain C3-41. Appl Environ Microbiol 2007; 73:3581-6. [PMID: 17400775 PMCID: PMC1932687 DOI: 10.1128/aem.02863-06] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacillus sphaericus cannot metabolize sugar since it lacks several of the enzymes necessary for glycolysis. Our results confirmed the presence of a glucokinase-encoding gene, glcK, and a phosphofructokinase-encoding gene, pfk, on the bacterial chromosome and expression of glucokinase during vegetative growth of B. sphaericus strains. However, no phosphoglucose isomerase gene (pgi) or phosphoglucose isomerase enzyme activity was detected in these strains. Furthermore, one glcK open reading frame was cloned from B. sphaericus strain C3-41 and then expressed in Escherichia coli. Biochemical analysis revealed that this gene encoded a protein with a molecular mass of 33 kDa and that the purified recombinant glucokinase had K(m) values of 0.52 and 0.31 mM for ATP and glucose, respectively. It has been proved that this ATP-dependent glucokinase can also phosphorylate fructose and mannose, and sequence alignment of the glcK gene indicated that it belongs to the ROK protein family. It is postulated that the absence of the phosphoglucose isomerase-encoding gene pgi in B. sphaericus might be one of the reasons for the inability of this bacterium to metabolize carbohydrates. Our findings provide additional data that further elucidate the specific metabolic pathway and could be used for genetic improvement of B. sphaericus.
Collapse
Affiliation(s)
- Bei Han
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
| | | | | | | | | | | |
Collapse
|
7
|
Guilhabert MR, Kirkpatrick BC. Identification of Xylella fastidiosa antivirulence genes: hemagglutinin adhesins contribute a biofilm maturation to X. fastidios and colonization and attenuate virulence. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2005; 18:856-68. [PMID: 16134898 DOI: 10.1094/mpmi-18-0856] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Xylella fastidosa, a gram-negative, xylem-limited bacterium, is the causal agent of several economically important plant diseases, including Pierce's disease (PD) and citrus variegated chlorosis (CVC). Until recently, the inability to transform or produce transposon mutants of X. fastidosa had been a major impediment to identifying X. fastidosa genes that mediate pathogen and plant interactions. A random transposon (Tn5) library of X. fastidosa was constructed and screened for mutants showing more severe symptoms and earlier grapevine death (hypervirulence) than did vines infected with the wild type. Seven hypervirulent mutants identified in this screen moved faster and reached higher populations than the wild type in grapevines. These results suggest that X. fastidosa attenuates its virulence in planta and that movement is important in X. fastidosa virulence. The mutated genes were sequenced and none had been described previously as antivirulence genes, although six of them showed similarity with genes of known functions in other organisms. One transposon insertion inactivated a hemagglutinin adhesin gene (PD2118), which we named HxfA. Another mutant in a second putative X. fastidosa hemagglutinin gene, PD1792 (HxfB), was constructed, and further characterization of these hxf mutants suggests that X. fastidosa hemagglutinins mediate contact between X. fastidosa cells, which results in colony formation and biofilm maturation within the xylem vessels.
Collapse
|
8
|
Fields MW, Russell JB. Transcriptional regulation of beta-glucanase activity in the ruminal bacterium, Prevotella bryantii B14. Curr Microbiol 2005; 50:155-9. [PMID: 15883874 DOI: 10.1007/s00284-004-4453-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2004] [Accepted: 10/15/2004] [Indexed: 11/26/2022]
Abstract
The ruminal bacterium, Prevotella bryantii B(1)4, grew more rapidly with glucose as an energy source than mannose (0.73 versus 0.47 h(-1)) and had 8-fold less beta-glucanase activity (50 versus 400 nmol reducing sugar mg protein(-1) min(-1)). Cultures that were provided with glucose and mannose had little beta-glucanase activity even though both sugars were utilized simultaneously. The observation that glucose and mannose were utilized simultaneously indicated that beta-glucanase expression was not merely a simple induction or inducer exclusion. When glucose was added to cultures growing on mannose, hexose flux through the glucomannokinase increased 1.5-fold, and this increase was associated with an almost immediate decrease in beta-glucanase mRNA. After only three generation (doubling) times, the amount of beta-glucanase mRNA was comparable to that observed in cells growing only with glucose. These results indicate that beta-glucanase activity is transcriptionally regulated. However, further work will be needed to define more precisely the nature of this regulation and to identify the intermediate in this response.
Collapse
Affiliation(s)
- Matthew W Fields
- Agricultural Research Service, USDA, Cornell University, Ithaca, NY, 14853, USA
| | | |
Collapse
|
9
|
Lunin VV, Li Y, Schrag JD, Iannuzzi P, Cygler M, Matte A. Crystal structures of Escherichia coli ATP-dependent glucokinase and its complex with glucose. J Bacteriol 2004; 186:6915-27. [PMID: 15466045 PMCID: PMC522197 DOI: 10.1128/jb.186.20.6915-6927.2004] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Intracellular glucose in Escherichia coli cells imported by phosphoenolpyruvate-dependent phosphotransferase system-independent uptake is phosphorylated by glucokinase by using ATP to yield glucose-6-phosphate. Glucokinases (EC 2.7.1.2) are functionally distinct from hexokinases (EC 2.7.1.1) with respect to their narrow specificity for glucose as a substrate. While structural information is available for ADP-dependent glucokinases from Archaea, no structural information exists for the large sequence family of eubacterial ATP-dependent glucokinases. Here we report the first structure determination of a microbial ATP-dependent glucokinase, that from E. coli O157:H7. The crystal structure of E. coli glucokinase has been determined to a 2.3-A resolution (apo form) and refined to final Rwork/Rfree factors of 0.200/0.271 and to 2.2-A resolution (glucose complex) with final Rwork/Rfree factors of 0.193/0.265. E. coli GlK is a homodimer of 321 amino acid residues. Each monomer folds into two domains, a small alpha/beta domain (residues 2 to 110 and 301 to 321) and a larger alpha+beta domain (residues 111 to 300). The active site is situated in a deep cleft between the two domains. E. coli GlK is structurally similar to Saccharomyces cerevisiae hexokinase and human brain hexokinase I but is distinct from the ADP-dependent GlKs. Bound glucose forms hydrogen bonds with the residues Asn99, Asp100, Glu157, His160, and Glu187, all of which, except His160, are structurally conserved in human hexokinase 1. Glucose binding results in a closure of the small domains, with a maximal Calpha shift of approximately 10 A. A catalytic mechanism is proposed that is consistent with Asp100 functioning as the general base, abstracting a proton from the O6 hydroxyl of glucose, followed by nucleophilic attack at the gamma-phosphoryl group of ATP, yielding glucose-6-phosphate as the product.
Collapse
Affiliation(s)
- Vladimir V Lunin
- Biotechnology Research Institute, NRCC, 6100 Royalmount Ave., Montreal, Quebec H4P 2R2 Canada
| | | | | | | | | | | |
Collapse
|
10
|
Caescu CI, Vidal O, Krzewinski F, Artenie V, Bouquelet S. Bifidobacterium longum requires a fructokinase (Frk; ATP:D-fructose 6-phosphotransferase, EC 2.7.1.4) for fructose catabolism. J Bacteriol 2004; 186:6515-25. [PMID: 15375133 PMCID: PMC516584 DOI: 10.1128/jb.186.19.6515-6525.2004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although the ability of Bifidobacterium spp. to grow on fructose as a unique carbon source has been demonstrated, the enzyme(s) needed to incorporate fructose into a catabolic pathway has hitherto not been defined. This work demonstrates that intracellular fructose is metabolized via the fructose-6-P phosphoketolase pathway and suggests that a fructokinase (Frk; EC 2.7.1.4) is the enzyme that is necessary and sufficient for the assimilation of fructose into this catabolic route in Bifidobacterium longum. The B. longum A10C fructokinase-encoding gene (frk) was expressed in Escherichia coli from a pET28 vector with an attached N-terminal histidine tag. The expressed enzyme was purified by affinity chromatography on a Co(2+)-based column, and the pH and temperature optima were determined. A biochemical analysis revealed that Frk displays the same affinity for fructose and ATP (Km(fructose) = 0.739 +/- 0.18 mM and Km(ATP) = 0.756 +/- 0.08 mM), is highly specific for D-fructose, and is inhibited by an excess of ATP (>12 mM). It was also found that frk is inducible by fructose and is subject to glucose-mediated repression. Consequently, this work presents the first characterization at the molecular and biochemical level of a fructokinase from a gram-positive bacterium that is highly specific for D-fructose.
Collapse
Affiliation(s)
- Cristina I Caescu
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR CNRS-USTL 8576, Université des Sciences et Technologies de Lille, Villeneuve d'Ascq, France
| | | | | | | | | |
Collapse
|
11
|
Ramos I, Guzmán S, Escalante L, Imriskova I, Rodríguez-Sanoja R, Sanchez S, Langley E. Glucose kinase alone cannot be responsible for carbon source regulation in Streptomyces peucetius var. caesius. Res Microbiol 2004; 155:267-74. [PMID: 15142624 DOI: 10.1016/j.resmic.2004.01.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2003] [Accepted: 01/26/2004] [Indexed: 11/29/2022]
Abstract
Using an antibiotic enrichment procedure, eight mutants of Streptomyces peucetius var. caesius were isolated for their sensitivity to the glucose analogue 2-deoxyglucose (DOG), from a DOG-resistant strain (Dog(R)). These mutants (Dog(S)) and their parent strain were examined for growth sensitivity to DOG, glucose kinase (Glk) activity, glucose uptake, and sensitivity to repression by glucose and other catabolites derived from it. No correlation was found between Glk levels or glucose uptake and carbon catabolite repression (CCR) in these strains. However, the ratio of glucose uptake to Glk activity, and thus the flux through glycolysis, seemed responsible for this effect. Among several products of glucose catabolism tested, fructose-1,6-bis-phosphate and phosphoenolpyruvate showed significant repression of anthracycline formation. These compounds also reduced anthracycline formation in a Dog(R) mutant insensitive to glucose repression. Our data suggest that Glk alone is not sufficient to elicit CCR in this microorganism, and gives the first physiological evidence supporting the hypothesis that some products of glucose catabolism are involved in CCR in Streptomyces.
Collapse
Affiliation(s)
- Itzel Ramos
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de Mexico, Mexico, D.F. 04510, Mexico
| | | | | | | | | | | | | |
Collapse
|
12
|
Mesak LR, Mesak FM, Dahl MK. Bacillus subtilis GlcK activity requires cysteines within a motif that discriminates microbial glucokinases into two lineages. BMC Microbiol 2004; 4:6. [PMID: 15018644 PMCID: PMC365027 DOI: 10.1186/1471-2180-4-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2003] [Accepted: 02/03/2004] [Indexed: 11/10/2022] Open
Abstract
Background Bacillus subtilis glucokinase (GlcK) (GenBank NP_390365) is an ATP-dependent kinase that phosphorylates glucose to glucose 6-phosphate. The GlcK protein has very low sequence identity (13.7%) to the Escherichia coli glucokinase (Glk) (GenBank P46880) and some other glucokinases (EC 2.7.1.2), yet glucose is merely its substrate. Our lab has previously isolated and characterized the glcK gene. Results Microbial glucokinases can be grouped into two different lineages. One of the lineages contains three conserved cysteine (C) residues in a CXCGX(2)GCXE motif. This motif is also present in the B. subtilis GlcK. The GlcK protein occurs in both monomer and homodimer. Each GlcK monomer has six cysteines. All cysteine residues have been mutated, one-by-one, into alanine (A). The in vivo GlcK enzymatic activity was assayed by functional complementation in E. coli UE26 (ptsG ptsM glk). Mutation of the three motif-specific residues led to an inactive enzyme. The other mutated forms retained, or in one case (GlcKC321A) even gained, activity. The fluorescence spectra of the GlcKC321A showed a red shift and enhanced fluorescence intensity compare to the wild type's. Conclusions Our results emphasize the necessity of cysteines within the CXCGX(2)GCXE motif for GlcK activity. On the other hand, the C321A mutation led to higher GlcKC321A enzymatic activity with respect to the wild type's, suggesting more adequate glucose phosphorylation.
Collapse
Affiliation(s)
- Lili R Mesak
- Department of Microbiology, Institute for Microbiology, Biochemistry and Genetics University of Erlangen-Nuremberg, Staudstrasse 5, 91058 Erlangen, and Department of Biology, University of Konstanz, Universitaetstrasse 1, 78457 Konstanz, Germany
- Current address: 412-2870 Cedarwood Dr., Ottawa, ON, K1V 8Y5, Canada
| | - Felix M Mesak
- Centre for Cancer Therapeutics, Ottawa Regional Cancer Centre, and Faculty of Medicine, University of Ottawa, 503 Smyth Rd., Ottawa, ON, K1H 1C4, Canada
| | - Michael K Dahl
- Department of Microbiology, Institute for Microbiology, Biochemistry and Genetics University of Erlangen-Nuremberg, Staudstrasse 5, 91058 Erlangen, and Department of Biology, University of Konstanz, Universitaetstrasse 1, 78457 Konstanz, Germany
| |
Collapse
|
13
|
Dörr C, Zaparty M, Tjaden B, Brinkmann H, Siebers B. The hexokinase of the hyperthermophile Thermoproteus tenax. ATP-dependent hexokinases and ADP-dependent glucokinases, teo alternatives for glucose phosphorylation in Archaea. J Biol Chem 2003; 278:18744-53. [PMID: 12626506 DOI: 10.1074/jbc.m301914200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The phosphorylation of glucose by different sugar kinases plays an essential role in Archaea because of the absence of a phosphoenolpyruvate-dependent transferase system characteristic for Bacteria. In the genome of the hyperthermophilic Archaeon Thermoproteus tenax a gene was identified with sequence similarity to glucokinases of the so-called ROK family (repressor protein, open reading frame, sugar kinase). The T. tenax enzyme, like the recently described ATP-dependent "glucokinase" from Aeropyrum pernix, shows the typical broad substrate specificity of hexokinases catalyzing not only phosphorylation of glucose but also of other hexoses such as fructose, mannose, or 2-deoxyglucose, and thus both enzymes represent true hexokinases. The T. tenax hexokinase shows strikingly low if at all any regulatory properties and thus fulfills no important control function at the beginning of the variant of the Embden-Meyerhof-Parnas pathway in T. tenax. Transcript analyses reveal that the hxk gene of T. tenax is cotranscribed with an upstream located orfX, which codes for an 11-kDa protein of unknown function. Growth-dependent studies and promoter analyses suggest that post-transcriptional RNA processing might be involved in the generation of the monocistronic hxk message, which is observed only under heterotrophic growth conditions. Data base searches revealed T. tenax hexokinase homologs in some archaeal, few eukaryal, and many bacterial genomes. Phylogenetic analyses confirm that the archaeal hexokinase is a member of the so-called ROK family, which, however, should be referred to as ROK group because it represents a group within the bacterial glucokinase fructokinase subfamily II of the hexokinase family. Thus, archaeal hexokinases represent a second major group of glucose-phosphorylating enzymes in Archaea beside the recently described archaeal ADP-dependent glucokinases, which were recognized as members of the ribokinase family. The distribution of the two types of sugar kinases, differing in their cosubstrate as well as substrate specificity, within Archaea is discussed on the basis of physiological constraints of the respective organisms.
Collapse
Affiliation(s)
- Christine Dörr
- Department of Microbiology, Universität Duisburg-Essen, Essen 45117, Germany
| | | | | | | | | |
Collapse
|
14
|
Arakawa K, Müller R, Mahmud T, Yu TW, Floss HG. Characterization of the early stage aminoshikimate pathway in the formation of 3-amino-5-hydroxybenzoic acid: the RifN protein specifically converts kanosamine into kanosamine 6-phosphate. J Am Chem Soc 2002; 124:10644-5. [PMID: 12207505 DOI: 10.1021/ja0206339] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The biosynthesis of 3-amino-5-hydroxybenzoic acid (AHBA), precursor of the ansamycin and mitomycin antibiotics, proceeds by the aminoshikimate pathway from 3,4-dideoxy-4-amino-D-arabino-heptulosonic acid 7-phosphate (aminoDAHP). Identification of RifN, product of one of three genes from the rifamycin biosynthetic gene cluster known to be essential for aminoDAHP formation, as a specific kanosamine (3-deoxy-3-amino-D-glucose) 6-kinase establishes kanosamine and its 6-phosphate as specific intermediates in AHBA formation. This suggests a hypothetical reaction sequence for aminoDAHP formation, and thus for the early steps of AHBA biosynthesis, starting from UDP-D-glucose and introducing the nitrogen by oxidation and transamination at C-3.
Collapse
Affiliation(s)
- Kenji Arakawa
- Department of Chemistry, Box 351700, University of Washington, Seattle, WA 98195-1700, USA
| | | | | | | | | |
Collapse
|
15
|
Yu TW, Bai L, Clade D, Hoffmann D, Toelzer S, Trinh KQ, Xu J, Moss SJ, Leistner E, Floss HG. The biosynthetic gene cluster of the maytansinoid antitumor agent ansamitocin from Actinosynnema pretiosum. Proc Natl Acad Sci U S A 2002; 99:7968-73. [PMID: 12060743 PMCID: PMC123004 DOI: 10.1073/pnas.092697199] [Citation(s) in RCA: 229] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2001] [Indexed: 11/18/2022] Open
Abstract
Maytansinoids are potent antitumor agents found in plants and microorganisms. To elucidate their biosynthesis at the biochemical and genetic level and to set the stage for their structure modification through genetic engineering, we have cloned two gene clusters required for the biosynthesis of the maytansinoid, ansamitocin, from a cosmid library of Actinosynnema pretiosum ssp. auranticum ATCC 31565. This is a rare case in which the genes involved in the formation of a secondary metabolite are dispersed in separate regions in an Actinomycete. A set of genes, asm22-24, asm43-45, and asm47, was identified for the biosynthesis of the starter unit, 3-amino-5-hydroxybenzoic acid (AHBA). Remarkably, there are two AHBA synthase gene homologues, which may have different functions in AHBA formation. Four type I polyketide synthase genes, asmA-D, followed by the downloading asm9, together encode eight homologous sets of enzyme activities (modules), each catalyzing a specific round of chain initiation, elongation, or termination steps, which assemble the ansamitocin polyketide backbone. Another set of genes, asm13-17, encodes the formation of an unusual "methoxymalonate" polyketide chain extension unit that, notably, seems to be synthesized on a dedicated acyl carrier protein rather than as a CoA thioester. Additional ORFs are involved in postsynthetic modifications of the initial polyketide synthase product, which include methylations, an epoxidation, an aromatic chlorination, and the introduction of acyl and carbamoyl groups. Tentative functions of several asm genes were confirmed by inactivation and heterologous expression.
Collapse
Affiliation(s)
- Tin-Wein Yu
- Department of Chemistry, Box 351700, University of Washington, Seattle, WA 98195-1700, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
The Glucomannokinase of the Gram-Negative Ruminal Bacterium, Prevotella bryantii B14, and its Sequence Conservation with Regulatory Glucokinases of Gram-Positive Bacteria. Anaerobe 2002. [DOI: 10.1006/anae.2002.0420] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
17
|
Yu TW, Muller R, Muller M, Zhang X, Draeger G, Kim CG, Leistner E, Floss HG. Mutational analysis and reconstituted expression of the biosynthetic genes involved in the formation of 3-amino-5-hydroxybenzoic acid, the starter unit of rifamycin biosynthesis in amycolatopsis Mediterranei S699. J Biol Chem 2001; 276:12546-55. [PMID: 11278540 DOI: 10.1074/jbc.m009667200] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To investigate a novel branch of the shikimate biosynthesis pathway operating in the formation of 3-amino-5-hydroxybenzoic acid (AHBA), the unique biosynthetic precursor of rifamycin and related ansamycins, a series of target-directed mutations and heterologous gene expressions were investigated in Amycolatopsis mediterranei and Streptomyces coelicolor. The genes involved in AHBA formation were inactivated individually, and the resulting mutants were further examined by incubating the cell-free extracts with known intermediates of the pathway and analyzing for AHBA formation. The rifL, -M, and -N genes were shown to be involved in the step(s) from either phosphoenolpyruvate/d-erythrose 4-phosphate or other precursors to 3,4-dideoxy-4-amino-d-arabino-heptulosonate 7-phosphate. The gene products of the rifH, -G, and -J genes resemble enzymes involved in the shikimate biosynthesis pathway (August, P. R., Tang, L., Yoon, Y. J., Ning, S., Müller, R., Yu, T.-W., Taylor, M., Hoffmann, D., Kim, C.-G., Zhang, X., Hutchinson, C. R., and Floss, H. G. (1998) Chem. Biol. 5, 69-79). Mutants of the rifH and -J genes produced rifamycin B at 1% and 10%, respectively, of the yields of the wild type; inactivation of the rifG gene did not affect rifamycin production significantly. Finally, coexpressing the rifG-N and -J genes in S. coelicolor YU105 under the control of the act promoter led to significant production of AHBA in the fermented cultures, confirming that seven of these genes are indeed necessary and sufficient for AHBA formation. The effects of deletion of individual genes from the heterologous expression cassette on AHBA formation duplicated the effects of the genomic rifG-N and -J mutations on rifamycin production, indicating that all these genes encode proteins with catalytic rather than regulatory functions in AHBA formation for rifamycin biosynthesis by A. mediterranei.
Collapse
Affiliation(s)
- T W Yu
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, USA.
| | | | | | | | | | | | | | | |
Collapse
|
18
|
Fields MW, Russell JB. The glucomannokinase of Prevotella bryantii B(1)4 and its potential role in regulating beta-glucanase expression. MICROBIOLOGY (READING, ENGLAND) 2001; 147:1035-1043. [PMID: 11283299 DOI: 10.1099/00221287-147-4-1035] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Prevotella bryantii B(1)4 has a transport system for glucose and mannose, but beta-glucanase expression is only catabolite-repressed by glucose. P bryantii B(1)4 cell extracts had ATP-dependent gluco- and mannokinase activities, and significant phosphoenolpyruvate- or GTP-dependent hexose phosphorylation was not observed. Mannose inhibited glucose phosphorylation (and vice versa), and activity gels indicated that a single protein was responsible for both activities. Glucose was phosphorylated at a faster rate than was mannose [V(max) 280 nmol hexose (mg protein)(-1) min(-1) versus 60 nmol hexose (mg protein)(-1) min(-1), respectively] and glucose was a better substrate for the kinase (K(m) 0.12 mM versus 1.2 mM, respectively). The purified glucomannokinase (1250-fold) had a molecular mass of 68 kDa, but SDS-PAGE gels indicated that it was a dimer (monomer 34.5 kDa). The N-terminus (25 residues) had an 8 amino acid segment that was homologous to other bacterial glucokinases. The glucomannokinase was competitively inhibited by the nonmetabolizable glucose analogue 2-deoxyglucose (2DG), and cells grown with glucose and 2DG had lower rates of glucose consumption than did cells given only glucose. When the ratio of 2DG to glucose was increased, the glucose consumption rate decreased and the beta-glucanase activity increased. The glucose consumption rate and the glucomannokinase activity of cells treated with 2DG were highly correlated (r(2)=0.98). This result suggested that glucomannokinase activity was either directly or indirectly regulating beta-glucanase expression.
Collapse
Affiliation(s)
- Matthew W Fields
- Department of Microbiology, Cornell University and 2Agricultural Research Service, USDA, Ithaca, NY 14853, USA
| | - James B Russell
- Department of Microbiology, Cornell University and 2Agricultural Research Service, USDA, Ithaca, NY 14853, USA
| |
Collapse
|
19
|
Abstract
The gram-positive bacterium Bacillus subtilisis capable of using numerous carbohydrates as single sources of carbon and energy. In this review, we discuss the mechanisms of carbon catabolism and its regulation. Like many other bacteria, B. subtilis uses glucose as the most preferred source of carbon and energy. Expression of genes involved in catabolism of many other substrates depends on their presence (induction) and the absence of carbon sources that can be well metabolized (catabolite repression). Induction is achieved by different mechanisms, with antitermination apparently more common in B. subtilis than in other bacteria. Catabolite repression is regulated in a completely different way than in enteric bacteria. The components mediating carbon catabolite repression in B. subtilis are also found in many other gram-positive bacteria of low GC content.
Collapse
Affiliation(s)
- J Stülke
- Lehrstuhl für Mikrobiologie, Institut für Mikrobiologie, Biochemie und Genetik der Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | | |
Collapse
|
20
|
Park SY, Kim HK, Yoo SK, Oh TK, Lee JK. Characterization of glk, a gene coding for glucose kinase of Corynebacterium glutamicum. FEMS Microbiol Lett 2000; 188:209-15. [PMID: 10913707 DOI: 10.1111/j.1574-6968.2000.tb09195.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The glk gene from Corynebacterium glutamicum was isolated by complementation using Escherichia coli ZSC113 (ptsG ptsM glk). We sequenced a total of 3072 bp containing the 969-bp open reading frame encoding glucose kinase (Glk). The glk gene has a deduced molecular mass of 34.2 kDa and contains a typical ATP binding site. Comparison with protein sequences revealed homologies to Glk from Streptomyces coelicolor (43%) and Bacillus megaterium (35%). The glk gene in C. glutamicum was inactivated on the chromosome via single crossover homologous recombination and the resulting glk mutant was characterized. Interestingly, the C. glutamicum glk mutant showed poor growth on rich medium such as LB medium or brain heart infusion medium in the presence or absence of glucose, fructose, maltose or sucrose as the sole carbon source. Growth yield was reduced significantly when maltose was used as the sole carbon source using minimal medium. The growth defect of glk mutant on rich medium was complemented by a plasmid-encoded glk gene. A chromosomal glk-lacZ fusion was constructed and used to monitor glk expression, and it was found that glk was expressed constitutively under all tested conditions with different carbon sources.
Collapse
Affiliation(s)
- S Y Park
- Environmental Bioresources Laboratory, Korea Research Institute of Bioscience and Biotechnology, College of Engineering, Yonsei University, Seoul, Korea
| | | | | | | | | |
Collapse
|
21
|
Yamamoto Y, Higuchi M, Poole LB, Kamio Y. Role of the dpr product in oxygen tolerance in Streptococcus mutans. J Bacteriol 2000; 182:3740-7. [PMID: 10850989 PMCID: PMC94545 DOI: 10.1128/jb.182.13.3740-3747.2000] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have previously identified and characterized the alkyl hydroperoxide reductase of Streptococcus mutans, which consists of two components, Nox-1 and AhpC. Deletion of both nox-1 and ahpC had no effect on the sensitivity of S. mutans to cumene hydroperoxide or H(2)O(2), implying that the existence of another antioxidant system(s) independent of the Nox-1-AhpC system compensates for the deficiency. Here, a new antioxidant gene (dpr for Dps-like peroxide resistance gene) was isolated from the S. mutans chromosome by its ability to complement an ahpCF deletion mutant of Escherichia coli with a tert-butyl hydroperoxide-hypersensitive phenotype. The dpr gene complemented the defect in peroxidase activity caused by the deletion of nox-1 and ahpC in S. mutans. Under aerobic conditions, the dpr disruption mutant carrying a spectinomycin resistance gene (dpr::Spc(r) mutant) grew as well as wild-type S. mutans in liquid medium. However, the dpr::Spc(r) mutant could not form colonies on an agar plate under air. In addition, neither the dpr::Spc(r) ahpC::Em(r)::nox-1 triple mutant nor the dpr::Spc(r) sod::Em(r) double mutant was able to grow aerobically in liquid medium. The 20-kDa dpr gene product Dpr is an iron-binding protein. Synthesis of Dpr was induced by exposure of S. mutans cells to air. We propose a mechanism by which Dpr confers aerotolerance on S. mutans.
Collapse
Affiliation(s)
- Y Yamamoto
- Laboratory of Applied Microbiology, Department of Molecular and Cell Biology, Graduate School of Agricultural Science, Tohoku University, Amamiya-machi, Aoba-ku, Sendai 981-8555, Japan
| | | | | | | |
Collapse
|
22
|
Concha MI, León G. Cloning, functional expression and partial characterization of the glucose kinase from Renibacterium salmoninarum. FEMS Microbiol Lett 2000; 186:97-101. [PMID: 10779719 DOI: 10.1111/j.1574-6968.2000.tb09088.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
The complete glcK gene from the fish pathogen Renibacterium salmoninarum, encoding a glucose kinase, was analyzed and expressed. The partial characterization of the recombinant enzyme confirmed that it belongs to a group of glucose kinases involved in carbon catabolite repression. Multiple sequence alignments were used to deduce a new consensus sequence for this family of bacterial proteins, characterized by several conserved Cys residues. This sequence was more specific and allowed the detection of the first eukaryotic protein of this family. The recombinant enzyme was inhibited by N-ethylmaleimide and the substrates protected the enzyme from this inhibition, suggesting the presence of Cys residues in or close to the active site.
Collapse
Affiliation(s)
- M I Concha
- Instituto de Bioquímica, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile.
| | | |
Collapse
|
23
|
Zalieckas JM, Wray LV, Fisher SH. trans-acting factors affecting carbon catabolite repression of the hut operon in Bacillus subtilis. J Bacteriol 1999; 181:2883-8. [PMID: 10217782 PMCID: PMC93733 DOI: 10.1128/jb.181.9.2883-2888.1999] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Bacillus subtilis, CcpA-dependent carbon catabolite repression (CCR) mediated at several cis-acting carbon repression elements (cre) requires the seryl-phosphorylated form of both the HPr (ptsH) and Crh (crh) proteins. During growth in minimal medium, the ptsH1 mutation, which prevents seryl phosphorylation of HPr, partially relieves CCR of several genes regulated by CCR. Examination of the CCR of the histidine utilization (hut) enzymes in cells grown in minimal medium showed that neither the ptsH1 nor the crh mutation individually had any affect on hut CCR but that hut CCR was abolished in a ptsH1 crh double mutant. In contrast, the ptsH1 mutation completely relieved hut CCR in cells grown in Luria-Bertani medium. The ptsH1 crh double mutant exhibited several growth defects in glucose minimal medium, including reduced rates of growth and growth inhibition by high levels of glycerol or histidine. CCR is partially relieved in B. subtilis mutants which synthesize low levels of active glutamine synthetase (glnA). In addition, these glnA mutants grow more slowly than wild-type cells in glucose minimal medium. The defects in growth and CCR seen in these mutants are suppressed by mutational inactivation of TnrA, a global nitrogen regulatory protein. The inappropriate expression of TnrA-regulated genes in this class of glnA mutants may deplete intracellular pools of carbon metabolites and thereby result in the reduction of the growth rate and partial relief of CCR.
Collapse
Affiliation(s)
- J M Zalieckas
- Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts 02118, USA
| | | | | |
Collapse
|
24
|
Mao Y, Varoglu M, Sherman DH. Molecular characterization and analysis of the biosynthetic gene cluster for the antitumor antibiotic mitomycin C from Streptomyces lavendulae NRRL 2564. CHEMISTRY & BIOLOGY 1999; 6:251-63. [PMID: 10099135 DOI: 10.1016/s1074-5521(99)80040-4] [Citation(s) in RCA: 130] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
BACKGROUND The mitomycins are natural products that contain a variety of functional groups, including aminobenzoquinone- and aziridine-ring systems. Mitomycin C (MC) was the first recognized bioreductive alkylating agent, and has been widely used clinically for antitumor therapy. Precursor-feeding studies showed that MC is derived from 3-amino-5-hydroxybenzoic acid (AHBA), D-glucosamine, L-methionine and carbamoyl phosphate. A genetically linked AHBA biosynthetic gene and MC resistance genes were identified previously in the MC producer Streptomyces lavendulae NRRL 2564. We set out to identify other genes involved in MC biosynthesis. RESULTS A cluster of 47 genes spanning 55 kilobases of S. lavendulae DNA governs MC biosynthesis. Fourteen of 22 disruption mutants did not express or overexpressed MC. Seven gene products probably assemble the AHBA intermediate through a variant of the shikimate pathway. The gene encoding the first presumed enzyme in AHBA biosynthesis is not, however, linked within the MC cluster. Candidate genes for mitosane nucleus formation and functionalization were identified. A putative MC translocase was identified that comprises a novel drug-binding and export system, which confers cellular self-protection on S. lavendulae. Two regulatory genes were also identified. CONCLUSIONS The overall architecture of the MC biosynthetic gene cluster in S. lavendulae has been determined. Targeted manipulation of a putative MC pathway regulator led to a substantial increase in drug production. The cloned genes should help elucidate the molecular basis for creation of the mitosane ring system, as well efforts to engineer the biosynthesis of novel natural products.
Collapse
Affiliation(s)
- Y Mao
- University of Minnesota, Department of Microbiology, Biological ProcessTechnology Institute, 1460 Mayo Memorial Building, Box 196 UFHC, 420 Delaware Street S.E., Minneapolis, MN 55455, USA
| | | | | |
Collapse
|
25
|
Zalieckas JM, Wray LV, Fisher SH. Expression of the Bacillus subtilis acsA gene: position and sequence context affect cre-mediated carbon catabolite repression. J Bacteriol 1998; 180:6649-54. [PMID: 9852010 PMCID: PMC107769 DOI: 10.1128/jb.180.24.6649-6654.1998] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Bacillus subtilis, carbon catabolite repression (CCR) of many genes is mediated at cis-acting carbon repression elements (cre) by the catabolite repressor protein CcpA. Mutations in transcription-repair coupling factor (mfd) partially relieve CCR at cre sites located downstream of transcriptional start sites by abolishing the Mfd-mediated displacement of RNA polymerase stalled at cre sites which act as transcriptional roadblocks. Although the acsA cre is centered 44.5 bp downstream of the acsA transcriptional start site, CCR of acsA expression is not affected by an mfd mutation. When the acsA cre is centered 161.5 bp downstream of the transcriptional start site for the unregulated tms promoter, CCR is partially relieved by the mfd mutation. Since CCR mediated at an acsA cre centered 44.5 bp downstream of the tms start site is not affected by the mfd mutation, the inability of Mfd to modulate CCR of acsA expression most likely results from the location of the acsA cre. Higher levels of CCR were found to occur at cre sites flanked by A+T-rich sequences than at cre sites bordered by G and C nucleotides. This suggests that nucleotides adjacent to the proposed 14-bp cre consensus sequence participate in the formation of the CcpA catabolite repression complex at cre sites. Examination of CCR of acsA expression revealed that this regulation required the Crh and seryl-phosphorylated form of the HPr proteins but not glucose kinase.
Collapse
Affiliation(s)
- J M Zalieckas
- Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts 02118, USA
| | | | | |
Collapse
|
26
|
Schönert S, Buder T, Dahl MK. Identification and enzymatic characterization of the maltose-inducible alpha-glucosidase MalL (sucrase-isomaltase-maltase) of Bacillus subtilis. J Bacteriol 1998; 180:2574-8. [PMID: 9573215 PMCID: PMC107205 DOI: 10.1128/jb.180.9.2574-2578.1998] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/1997] [Accepted: 03/03/1998] [Indexed: 02/07/2023] Open
Abstract
A gene coding for a putative alpha-glucosidase has been identified in the open reading frame yvdL (now termed malL), which was sequenced as part of the Bacillus subtilis genome project. The enzyme was overproduced in Escherichia coli and purified. Further analyses indicate that MalL is a specific oligo-1,4-1,6-alpha-glucosidase (sucrase-maltase-isomaltase). MalL expression in B. subtilis requires maltose induction and is subject to carbon catabolite repression by glucose and fructose. Insertional mutagenesis of malL resulted in a complete inactivation of the maltose-inducible alpha-glucosidase activity in crude protein extracts and a Mal- phenotype.
Collapse
Affiliation(s)
- S Schönert
- Lehrstuhl für Mikrobiologie, Institut für Mikrobiologie, Biochemie und Genetik, Universität Erlangen-Nürnberg, Erlangen, Germany
| | | | | |
Collapse
|