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Zhang L, Xu H, Cheng H, Song F, Zhang J, Peng Q. Transcriptional regulation of cellobiose utilization by PRD-domain containing Sigma54-dependent transcriptional activator (CelR) and catabolite control protein A (CcpA) in Bacillus thuringiensis. Front Microbiol 2024; 15:1160472. [PMID: 38357353 PMCID: PMC10864463 DOI: 10.3389/fmicb.2024.1160472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 01/16/2024] [Indexed: 02/16/2024] Open
Abstract
Cellobiose, a β-1,4-linked glucose dimer, is a major cellodextrin resulting from the enzymatic hydrolysis of cellulose. It is a major source of carbon for soil bacteria. In bacteria, the phosphoenolpyruvate (PEP): carbohydrate phosphotransferase system (PTS), encoded by the cel operon, is responsible for the transport and utilization of cellobiose. In this study, we analyzed the transcription and regulation of the cel operon in Bacillus thuringiensis (Bt). The cel operon is composed of five genes forming one transcription unit. β-Galactosidase assays revealed that cel operon transcription is induced by cellobiose, controlled by Sigma54, and positively regulated by CelR. The HTH-AAA+ domain of CelR recognized and specifically bound to three possible binding sites in the celA promoter region. CelR contains two PTS regulation domains (PRD1 and PRD2), which are separated by two PTS-like domains-the mannose transporter enzyme IIA component domain (EIIAMan) and the galactitol transporter enzyme IIB component domain (EIIBGat). Mutations of His-546 on the EIIAMan domain and Cys-682 on the EIIBGat domain resulted in decreased transcription of the cel operon, and mutations of His-839 on PRD2 increased transcription of the cel operon. Glucose repressed the transcription of the cel operon and catabolite control protein A (CcpA) positively regulated this process by binding the cel promoter. In the celABCDE and celR mutants, PTS activities were decreased, and cellobiose utilization was abolished, suggesting that the cel operon is essential for cellobiose utilization. Bt has been widely used as a biological pesticide. The metabolic properties of Bt are critical for fermentation. Nutrient utilization is also essential for the environmental adaptation of Bt. Glucose is the preferred energy source for many bacteria, and the presence of the phosphotransferase system allows bacteria to utilize other sugars in addition to glucose. Cellobiose utilization pathways have been of particular interest owing to their potential for developing alternative energy sources for bacteria. The data presented in this study improve our understanding of the transcription patterns of cel gene clusters. This will further help us to better understand how cellobiose is utilized for bacterial growth.
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Affiliation(s)
| | | | | | | | | | - Qi Peng
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
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Huang L, Han G, Crickmore N, Li C, Xia Y, Song F, Xu J. Characterization of a novel cell wall hydrolase CwlE involved in Bacillus thuringiensis subsp . israelensis mother cell lysis. Front Microbiol 2023; 14:1250542. [PMID: 37829449 PMCID: PMC10565116 DOI: 10.3389/fmicb.2023.1250542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 09/15/2023] [Indexed: 10/14/2023] Open
Abstract
Cell wall hydrolases are ubiquitous among spore-form bacteria and essential for mother cell lysis. In this study, a novel cell wall hydrolase gene cwlE involved in mother cell lysis was characterized from Bacillus thuringiensis subsp. israelensis (Bti) strain Bt-59. cwlE was specifically expressed in Bti and located in the large plasmid carrying the insecticidal genes. The encoded CwlE protein consists of a MurNAc-LAA domain and two highly conserved catalytic residues (E26 and E151). The recombinant CwlE-His protein was able to digest the cell wall of Bti, indicating that CwlE is an N-acetylmuramoyl-L-alanine amidase. Transcriptional analysis indicated that cwlE began to express at the early stage of stationary phase and was controlled by SigE. Single mutation of cwlE gene delayed Bti mother cell lysis, while double mutation of cwlE and sigK completely blocked Bti mother cell lysis. After exposure to UV light to deactivate the crystal proteins, the level of decrease of insecticidal activity against mosquito larvae of Bt-59 (ΔcwlE-sigK) was less than that observed for Bt-59. This study elucidates the mechanism of Bti mother cell lysis and provides an effective strategy for mosquito control using Bt products with increased persistence.
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Affiliation(s)
- Lixin Huang
- Department of Applied Microbiology, Lixiahe District Institute of Agricultural Sciences in Jiangsu/National Agricultural Experimental Station for Agricultural Microbiology in Yangzhou, Yangzhou, China
| | - Guangjie Han
- Department of Applied Microbiology, Lixiahe District Institute of Agricultural Sciences in Jiangsu/National Agricultural Experimental Station for Agricultural Microbiology in Yangzhou, Yangzhou, China
| | - Neil Crickmore
- Department of Biochemistry, School of Biological Sciences, University of Sussex, Brighton, United Kingdom
| | - Chuanming Li
- Department of Applied Microbiology, Lixiahe District Institute of Agricultural Sciences in Jiangsu/National Agricultural Experimental Station for Agricultural Microbiology in Yangzhou, Yangzhou, China
| | - Yang Xia
- Department of Applied Microbiology, Lixiahe District Institute of Agricultural Sciences in Jiangsu/National Agricultural Experimental Station for Agricultural Microbiology in Yangzhou, Yangzhou, China
| | - Fuping Song
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jian Xu
- Department of Applied Microbiology, Lixiahe District Institute of Agricultural Sciences in Jiangsu/National Agricultural Experimental Station for Agricultural Microbiology in Yangzhou, Yangzhou, China
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Zhang R, Luo Y, Gang L, Xu Y, Zhang X, Peng Q, Slamti L, Lereclus D, Wang G, Song F. Key amino acids residues enhance the ability of CpcR to activate cry gene expression in Bacillus thuringiensis. Res Microbiol 2023; 174:104051. [PMID: 36907231 DOI: 10.1016/j.resmic.2023.104051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 02/11/2023] [Accepted: 03/02/2023] [Indexed: 03/13/2023]
Abstract
Typical Bacillus thuringiensis (Bt) produces one or more parasporal crystals composed of insecticidal Cry proteins during the sporulation, and the parasporal crystals and spores are produced from the same cell. Strain Bt LM1212 is different from typical Bt strains in that its crystals and spores are produced in different cells. Previous studies have found that the cell differentiation process of Bt LM1212 is related to the transcription factor CpcR which activates the cry-gene promoters. In addition, CpcR could activate the Bt LM1212 cry35-like gene promoter (P35) when introduced in the heterologous HD73- strain. It was shown that P35 was only activated in non-sporulating cells. In this study, the peptidic sequences of CpcR homologous proteins found in other strains of the Bacillus cereus group were used as references to identify two key amino acid sites for CpcR activity. The function of these amino acids was investigated by measuring P35 activation by CpcR in strain HD73-. These results will lay a foundation for the optimization of the insecticidal protein expression system in non-sporulating cells.
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Affiliation(s)
- Ruibin Zhang
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China; State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
| | - Yang Luo
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
| | - Lili Gang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
| | - Yanrong Xu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
| | - Xin Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
| | - Qi Peng
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
| | - Leyla Slamti
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France.
| | - Didier Lereclus
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France.
| | - Guirong Wang
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China; State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
| | - Fuping Song
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
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Guerrero M. GG. Sporulation, Structure Assembly, and Germination in the Soil Bacterium Bacillus thuringiensis: Survival and Success in the Environment and the Insect Host. MICROBIOLOGY RESEARCH 2023. [DOI: 10.3390/microbiolres14020035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023] Open
Abstract
Bacillus thuringiensis (Bt) is a rod-shaped, Gram-positive soil bacterium that belongs to the phylum Firmicutes and the genus Bacillus. It is a spore-forming bacterium. During sporulation, it produces a wide range of crystalline proteins that are toxic to different orders of insects. Sporulation, structure assembly, and germination are essential stages in the cell cycle of B. thuringiensis. The majority of studies on these issues have focused on the model organism Bacillus subtilis, followed by Bacillus cereus and Bacillus anthracis. The machinery for sporulation and germination extrapolated to B. thuringiensis. However, in the light of recent findings concerning the role of the sporulation proteins (SPoVS), the germination receptors (Gr), and the cortical enzymes in Bt, the theory strengthened that conservation in sporulation, structure assembly, and germination programs drive the survival and success of B. thuringiensis in the environment and the insect host. In the present minireview, the latter pinpointed and reviewed.
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Affiliation(s)
- Gloria G. Guerrero M.
- Unidad Académica de Ciencias Biológicas, Laboratorio de Immunobiología, Universidad Autónoma de Zacatecas, Av. Preparatoria S/N, Col. Agronomicas, Zacatecas 98066, Mexico
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Identification and Functional Characterization of Two Homologous SpoVS Proteins Involved in Sporulation of Bacillus thuringiensis. Microbiol Spectr 2021; 9:e0088121. [PMID: 34612699 PMCID: PMC8510167 DOI: 10.1128/spectrum.00881-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Sporulation is an important part of the life cycle of Bacillus thuringiensis and the basis for the production of parasporal crystals. This study identifies and characterizes two homologous spoVS genes (spoVS1 and spoVS2) in B. thuringiensis, both of whose expression is dependent on the σH factor. The disruption of spoVS1 and spoVS2 resulted in defective B. thuringiensis sporulation. Similar to Bacillus subtilis, B. thuringiensis strain HD(ΔspoVS1) mutants showed delayed formation of the polar septa, decreased sporulation efficiency, and blocked spore release. Different from B. subtilis, B. thuringiensis HD(ΔspoVS1) mutants had disporic septa and failed to complete engulfment in some cells. Moreover, HD(ΔspoVS2) mutants had delayed spore release. The effect of spoVS1 deletion on polar septum delay and sporulation efficiency could be compensated by spoVS2. β-Galactosidase activity analysis showed that the expression of pro-sigE and spoIIE decreased to different degrees in the HD(ΔspoVS1) and HD(ΔspoVS2) mutants. The different effects of the two mutations on the expression of sporulation genes led to decreases in Cry1Ac production of different levels. IMPORTANCE There is only one spoVS gene in B. subtilis, and its effects on sporulation have been reported. In this study, two homologous spoVS genes were found and identified in B. thuringiensis. The different effects on sporulation and parasporal crystal protein production in B. thuringiensis and their relationship were investigated. We found that these two homologous spoVS genes are highly conserved in the Bacillus cereus group, and therefore, the functional characterization of SpoVS is helpful to better understand the sporulation processes of members of the Bacillus cereus group.
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Huang L, Xu L, Han G, Crickmore N, Song F, Xu J. Characterization of CwlC, an autolysin, and its role in mother cell lysis of Bacillus thuringiensis subsp. israelensis. Lett Appl Microbiol 2021; 74:92-102. [PMID: 34695235 DOI: 10.1111/lam.13590] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 10/13/2021] [Accepted: 10/15/2021] [Indexed: 11/27/2022]
Abstract
Bacillus thuringiensis subsp. israelensis (Bti) has been proven to efficiently control mosquitoes, of which many species are important vectors of human disease. The larvicidal action is attributed to the parasporal crystals formed in the sporulating cells and released upon cell autolysis. In this study, a sporulation-specific cwlC gene that encodes an N-acetylmuramoyl-L -alanine amidase was characterized in Bti strain Bt-59. CwlC was the only cell wall hydrolase in Bti found to contain both MurNAc-LAA and Amidase02_C domains. A recombinant CwlC-His protein was able to digest the Bacillus cell wall. Deletion of the cwlC gene delayed Bti mother cell lysis without impacting vegetative growth or insecticidal efficacy. Transcriptional analyses indicated that cwlC was expressed at the late sporulation stage and was controlled by SigK. Two other cell wall hydrolase genes, cwlB and cwlE, with high expression levels at T14 in Bt-59, were also identified. Like cwlC, cwlB expression was controlled by SigK; in contrast, cwlE was found not to be under the control of this sigma factor and unlike the other two, its gene was found to be plasmid encoded.
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Affiliation(s)
- L Huang
- Department of Applied Microbiology, Jiangsu Lixiahe District Institute of Agricultural Sciences/National Agricultural Experimental Station for Agricultural Microbiology, Yangzhou, China
| | - L Xu
- Department of Applied Microbiology, Jiangsu Lixiahe District Institute of Agricultural Sciences/National Agricultural Experimental Station for Agricultural Microbiology, Yangzhou, China.,State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - G Han
- Department of Applied Microbiology, Jiangsu Lixiahe District Institute of Agricultural Sciences/National Agricultural Experimental Station for Agricultural Microbiology, Yangzhou, China
| | - N Crickmore
- Department of Biochemistry, School of Biological Sciences, University of Sussex, Brighton, UK
| | - F Song
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - J Xu
- Department of Applied Microbiology, Jiangsu Lixiahe District Institute of Agricultural Sciences/National Agricultural Experimental Station for Agricultural Microbiology, Yangzhou, China
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Transition Phase Regulator AbrB Positively Regulates the sip1Ab1 Gene Expression in Bacillus thuringiensis. Microbiol Spectr 2021; 9:e0007521. [PMID: 34319140 PMCID: PMC8552724 DOI: 10.1128/spectrum.00075-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Bacillus thuringiensis secreted insecticidal proteins (Sip) are a secretion that is toxic to coleopteran pests. However, the transcriptional mechanism of sip genes is still unknown. The transcriptional regulation of the sip1Ab1 gene and the expression of the Sip1Ab1 protein were investigated in this study. The results demonstrated that the secretion of the Sip1Ab1 protein in HD73 was almost the same as that in the original QZL38 strain during the transition phase. Analysis of the β-galactosidase activities of sip1Ab1-lacZ in both the HD73 and abrB mutant strains indicated that the transcription of sip1Ab1 is dependent on AbrB. Electrophoretic mobility shift assays showed that AbrB could bind with the sip1Ab1 promoter, and two binding sites of AbrB in the region of the promoter of sip1Ab1 were determined by DNase I footprinting assays. All of the above-described results proved that AbrB positively regulates the sip1Ab1 gene. IMPORTANCEBacillus thuringiensis Sip proteins are secreted insecticidal toxins that are toxic to coleopteran pests. In this study, we investigated the transcriptional mechanism of the sip gene and showed strong evidence that Sip1Ab1 is secreted in the transition phase and that AbrB, a transition phase regulator that is usually a repressor, positively and directly regulates sip1Ab1. Reports of AbrB positive regulation are rare, even in Bacillus subtilis. To the best of our knowledge, no toxic gene has been reported to be positively regulated by AbrB in Bacillus species.
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Rap-Phr Systems from Plasmids pAW63 and pHT8-1 Act Together To Regulate Sporulation in the Bacillus thuringiensis Serovar kurstaki HD73 Strain. Appl Environ Microbiol 2020; 86:AEM.01238-20. [PMID: 32680861 DOI: 10.1128/aem.01238-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Accepted: 07/13/2020] [Indexed: 02/07/2023] Open
Abstract
Bacillus thuringiensis is a Gram-positive spore-forming bacterium pathogenic to various insect species. This property is due to the Cry toxins encoded by plasmid genes and mostly produced during sporulation. B. thuringiensis contains a remarkable number of extrachromosomal DNA molecules and a great number of plasmid rap-phr genes. Rap-Phr quorum-sensing systems regulate different bacterial processes, notably the commitment to sporulation in Bacillus species. Rap proteins are quorum sensors acting as phosphatases on Spo0F, an intermediate of the sporulation phosphorelay, and are inhibited by Phr peptides that function as signaling molecules. In this study, we characterize the Rap63-Phr63 system encoded by the pAW63 plasmid from the B. thuringiensis serovar kurstaki HD73 strain. Rap63 has moderate activity on sporulation and is inhibited by the Phr63 peptide. The rap63-phr63 genes are cotranscribed, and the phr63 gene is also transcribed from a σH-specific promoter. We show that Rap63-Phr63 regulates sporulation together with the Rap8-Phr8 system harbored by plasmid pHT8_1 of the HD73 strain. Interestingly, the deletion of both phr63 and phr8 genes in the same strain has a greater negative effect on sporulation than the sum of the loss of each phr gene. Despite the similarities in the Phr8 and Phr63 sequences, there is no cross talk between the two systems. Our results suggest a synergism of these two Rap-Phr systems in the regulation of the sporulation of B. thuringiensis at the end of the infectious cycle in insects, thus pointing out the roles of the plasmids in the fitness of the bacterium.IMPORTANCE The life cycle of Bacillus thuringiensis in insect larvae is regulated by quorum-sensing systems of the RNPP family. After the toxemia caused by Cry insecticidal toxins, the sequential activation of these systems allows the bacterium to trigger first a state of virulence (regulated by PlcR-PapR) and then a necrotrophic lifestyle (regulated by NprR-NprX); ultimately, sporulation is controlled by the Rap-Phr systems. Our study describes a new rap-phr operon carried by a B. thuringiensis plasmid and shows that the Rap protein has a moderate effect on sporulation. However, this system, in combination with another plasmidic rap-phr operon, provides effective control of sporulation when the bacteria develop in the cadavers of infected insect larvae. Overall, this study highlights the important adaptive role of the plasmid Rap-Phr systems in the developmental fate of B. thuringiensis and its survival within its ecological niche.
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Transcription in the acetoin catabolic pathway is regulated by AcoR and CcpA in Bacillus thuringiensis. Microbiol Res 2020; 235:126438. [PMID: 32088504 DOI: 10.1016/j.micres.2020.126438] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 02/11/2020] [Accepted: 02/11/2020] [Indexed: 01/04/2023]
Abstract
Acetoin (3-hydroxy-2-butanone) is an important physiological metabolic product in many microorganisms. Acetoin breakdown is catalyzed by the acetoin dehydrogenase enzyme system (AoDH ES), which is encoded by acoABCL operon. In this study, we analyzed transcription and regulation of the aco operon in Bacillus thuringiensis (Bt). RT-PCR analysis revealed that acoABCL forms one transcriptional unit. The Sigma 54 controlled consensus sequence was located 12 bp from the acoA transcriptional start site (TSS). β-galactosidase assay revealed that aco operon transcription is induced by acetoin, controlled by sigma 54, and positively regulated by AcoR. The HTH domain of AcoR recognized and specifically bound to a 13-bp inverted repeat region that participates in 30-bp fragment mapping 81 bp upstream of the acoA TSS. The GAF domain in AcoR represses enhancer transcriptional activity at the acoA promoter. Transcriptions of the aco operon and acoR were repressed by glucose via CcpA, and CcpA specifically bound to sequences within the acoR promoter fragment. In the acoABCL and acoR mutants, acetoin use was abolished, suggesting that the aco operon is essential for utilization of acetoin. The data presented here improve our understanding of the regulation of the aco gene cluster in bacteria.
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Lv J, Zhang X, Gao T, Cui T, Peng Q, Zhang J, Song F. Effect of the spoIIID mutation on mother cell lysis in Bacillus thuringiensis. Appl Microbiol Biotechnol 2019; 103:4103-4112. [PMID: 30953122 DOI: 10.1007/s00253-019-09722-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 02/19/2019] [Accepted: 02/23/2019] [Indexed: 11/28/2022]
Abstract
SpoIIID is a small, sequence-specific DNA-binding protein which can direct many genes' transcription and has an effect on spore formation in Bacillus subtilis. We investigated the role of SpoIIID in mother cell lysis in Bacillus thuringiensis. A β-galactosidase assay based on the promoter fusions with lacZ indicated that the sigK gene was positively regulated by SpoIIID and σK negatively regulated the expression of sigE. The spoIIID mutant strain exhibited no mother cell lysis in Schaeffer's sporulation medium (SSM) but did in ½ Luria-Bertani (LB) medium. cwlC is an essential hydrolase gene for mother cell lysis. Moreover, the expression of a PcwlC-lacZ fusion in spoIIID mutant was proved to be higher in ½ LB medium than in SSM. HD (ΔspoIIID)(ΔcwlC) mutant was obtained by knocking out the cwlC gene in HD(ΔspoIIID) and displayed no mother cell lysis in both SSM and ½ LB mediums. The deletion of spoIIID decreased the crystal protein production in HD73. The expression of Porf1cry8E and P5014 promoter fusions with lacZ gene in the acrystalliferous HD-(ΔspoIIID) mutant showed similar activity to that in the acrystalliferous HD73- strain before T7 and slightly higher than that in the acrystalliferous HD73- after T7. Sodium dodecyl sulfate polyacrylamide gel electrophoresis showed that Cry1Ac production in HD-(ΔspoIIID) directed by the Porf1cry8E and P5014 promoters was at a similar level as that in HD73 wild strain. Altogether, these results suggested that the spoIIID mutant with Porf1cry8E or P5014 promoters could be an alternative delivery system for cry gene expression with no mature spore formation and medium-dependent mother cell lysis.
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Affiliation(s)
- Jing Lv
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Xin Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Tantan Gao
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Tingting Cui
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Qi Peng
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Jie Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Fuping Song
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China.
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Novel Cell Wall Hydrolase CwlC from Bacillus thuringiensis Is Essential for Mother Cell Lysis. Appl Environ Microbiol 2018; 84:AEM.02640-17. [PMID: 29374039 DOI: 10.1128/aem.02640-17] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 01/10/2018] [Indexed: 11/20/2022] Open
Abstract
In this study, a sporulation-specific gene (tentatively named cwlC) involved in mother cell lysis in Bacillus thuringiensis was characterized. The encoded CwlC protein consists of an N-terminal N-acetylmuramoyl-l-alanine amidase (MurNAc-LAA) domain and a C-terminal amidase02 domain. The recombinant histidine-tagged CwlC proteins purified from Escherichia coli were able to directly bind to and digest the B. thuringiensis cell wall. The CwlC point mutations at the two conserved glutamic acid residues (Glu-24 and Glu-140) shown to be critical for the catalytic activity in homologous amidases resulted in a complete loss of cell wall lytic activity, suggesting that CwlC is an N-acetylmuramoyl-l-alanine amidase. Results of transcriptional analyses indicated that cwlC is transcribed as a monocistronic unit and that its expression is dependent on sporulation sigma factor K (σK). Deletion of cwlC completely blocked mother cell lysis during sporulation without impacting the sporulation frequency, Cry1Ac protein production, and insecticidal activity. Taken together, our data suggest that CwlC is an essential cell wall hydrolase for B. thuringiensis mother cell lysis during sporulation. Engineered B. thuringiensis strains targeting cwlC, which allows the crystal inclusion to remain encapsulated in the mother cell at the end of sporulation, may have the potential to become more effective biological control agents in agricultural applications since the crystal inclusion remains encapsulated in the mother cell at the end of sporulation.IMPORTANCE Mother cell lysis has been well studied in Bacillus subtilis, which involves three distinct yet functionally complementary cell wall hydrolases. In this study, a novel cell wall hydrolase, CwlC, was investigated and found to be essential for mother cell lysis in Bacillus thuringiensis CwlC of B. thuringiensis only shows 9 and 21% sequence identity with known B. subtilis mother cell hydrolases CwlB and CwlC, respectively, suggesting that mechanisms of mother cell lysis may differ between B. subtilis and B. thuringiensis The cwlC gene deletion completely blocked the release of spores and crystals from the mother cell without affecting insecticidal activity. This may provide a new effective strategy for crystal encapsulation against UV light inactivation.
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A strong promoter of a non-cry gene directs expression of the cry1Ac gene in Bacillus thuringiensis. Appl Microbiol Biotechnol 2018. [DOI: 10.1007/s00253-018-8836-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Peng Q, Wu J, Chen X, Qiu L, Zhang J, Tian H, Song F. Disruption of Two-component System LytSR Affects Forespore Engulfment in Bacillus thuringiensis. Front Cell Infect Microbiol 2017; 7:468. [PMID: 29164075 PMCID: PMC5675857 DOI: 10.3389/fcimb.2017.00468] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 10/23/2017] [Indexed: 11/13/2022] Open
Abstract
Two-component regulatory systems (TCSs) play pivotal roles in bacteria sensing many different stimuli from environment. Here, we investigated the role of the LytSR TCS in spore formation in Bacillus thuringiensis (Bt) subsp. kurstaki HD73. lacZ gene fusions revealed that the transcription of the downstream genes, lrgAB, encoding two putative membrane-associated proteins, is regulated by LytSR. The sporulation efficiency of a lytSR mutant was significantly lower than that of wild-type HD73. A confocal microscopic analysis demonstrated that LytSR modulates the process of forespore engulfment. Moreover, the transcription of the lytSR operon is regulated by the mother-cell transcription factor SigE, whereas the transcription of the sporulation gene spoIIP was reduced in the lytSR mutant, as demonstrated with a β-galactosidase activity assay. These results suggest that LytSR modulates forespore engulfment by affecting the transcription of the spoIIP gene in Bt.
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Affiliation(s)
- Qi Peng
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jianbo Wu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.,Institute of Food Science and Technology, Hebei Agricultural University, Baoding, China
| | - Xiaomin Chen
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Lili Qiu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jie Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Hongtao Tian
- Institute of Food Science and Technology, Hebei Agricultural University, Baoding, China
| | - Fuping Song
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
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Adalat R, Saleem F, Crickmore N, Naz S, Shakoori AR. In Vivo Crystallization of Three-Domain Cry Toxins. Toxins (Basel) 2017; 9:toxins9030080. [PMID: 28282927 PMCID: PMC5371835 DOI: 10.3390/toxins9030080] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 02/10/2017] [Accepted: 02/23/2017] [Indexed: 12/13/2022] Open
Abstract
Bacillus thuringiensis (Bt) is the most successful, environmentally-friendly, and intensively studied microbial insecticide. The major characteristic of Bt is the production of proteinaceous crystals containing toxins with specific activity against many pests including dipteran, lepidopteran, and coleopteran insects, as well as nematodes, protozoa, flukes, and mites. These crystals allow large quantities of the protein toxins to remain stable in the environment until ingested by a susceptible host. It has been previously established that 135 kDa Cry proteins have a crystallization domain at their C-terminal end. In the absence of this domain, Cry proteins often need helper proteins or other factors for crystallization. In this review, we classify the Cry proteins based on their requirements for crystallization.
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Affiliation(s)
- Rooma Adalat
- Department of Biotechnology, Lahore College for Women University, Lahore 54590, Pakistan.
| | - Faiza Saleem
- Department of Biotechnology, Lahore College for Women University, Lahore 54590, Pakistan.
| | - Neil Crickmore
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RH, UK.
| | - Shagufta Naz
- Department of Biotechnology, Lahore College for Women University, Lahore 54590, Pakistan.
| | - Abdul Rauf Shakoori
- School of Biological Sciences, University of the Punjab, Quaid-i-Azam Campus, Lahore 54590, Pakistan.
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Peng Q, Liu C, Wang B, Yang M, Wu J, Zhang J, Song F. Sox transcription in sarcosine utilization is controlled by Sigma(54) and SoxR in Bacillus thuringiensis HD73. Sci Rep 2016; 6:29141. [PMID: 27404799 PMCID: PMC4941409 DOI: 10.1038/srep29141] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 06/10/2016] [Indexed: 12/04/2022] Open
Abstract
Sarcosine oxidase catalyzes the oxidative demethylation of sarcosine to yield glycine, formaldehyde, and hydrogen peroxide. In this study, we analyzed the transcription and regulation of the sox locus, including the sarcosine oxidase-encoding genes in Bacillus thuringiensis (Bt). RT-PCR analysis revealed that the sox locus forms two opposing transcriptional units: soxB (soxB/E/F/G/H/I) and soxR (soxR/C/D/A). The typical −12/−24 consensus sequence was located 15 bp and 12 bp from the transcriptional start site (TSS) of soxB and soxC, respectively. Promoter-lacZ fusion assays showed that the soxB promoter is controlled by the Sigma54 factor and is activated by the Sigma54-dependent transcriptional regulator SoxR. SoxR also inhibits its own expression. Expression from the PsoxCR promoter, which is responsible for the transcription of soxC, soxD, and soxA, is Sigma54-dependent and requires SoxR. An 11-bp inverted repeat sequence was identified as SoxR binding site upstream of the soxB TSS. Purified SoxR specifically bound a DNA fragment containing this region. Mutation or deletion of this sequence abolished the transcriptional activities of soxB and soxC. Thus, SoxR binds to the same sequence to activate the transcription of soxB and soxC. Sarcosine utilization was abolished in soxB and soxR mutants, suggesting that the sox locus is essential for sarcosine utilization.
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Affiliation(s)
- Qi Peng
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Chunxia Liu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Bo Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.,College of Life Sciences, Northeast Agriculture University, Harbin, China
| | - Min Yang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jianbo Wu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jie Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Fuping Song
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
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The Regulation of Exosporium-Related Genes in Bacillus thuringiensis. Sci Rep 2016; 6:19005. [PMID: 26805020 PMCID: PMC4750369 DOI: 10.1038/srep19005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 12/02/2015] [Indexed: 11/09/2022] Open
Abstract
Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis (Bt) are spore-forming members of the Bacillus cereus group. Spores of B. cereus group species are encircled by exosporium, which is composed of an external hair-like nap and a paracrystalline basal layer. Despite the extensive studies on the structure of the exosporium-related proteins, little is known about the transcription and regulation of exosporium gene expression in the B. cereus group. Herein, we studied the regulation of several exosporium-related genes in Bt. A SigK consensus sequence is present upstream of genes encoding hair-like nap proteins (bclA and bclB), basal layer proteins (bxpA, bxpB, cotB, and exsY ), and inosine hydrolase (iunH). Mutation of sigK decreased the transcriptional activities of all these genes, indicating that the transcription of these genes is controlled by SigK. Furthermore, mutation of gerE decreased the transcriptional activities of bclB, bxpB, cotB, and iunH but increased the expression of bxpA, and GerE binds to the promoters of bclB, bxpB, cotB, bxpA, and iunH. These results suggest that GerE directly regulates the transcription of these genes, increasing the expression of bclB, bxpB, cotB, and iunH and decreasing that of bxpA. These findings provide insight into the exosporium assembly process at the transcriptional level.
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Activation of gab cluster transcription in Bacillus thuringiensis by γ-aminobutyric acid or succinic semialdehyde is mediated by the Sigma 54-dependent transcriptional activator GabR. BMC Microbiol 2014; 14:306. [PMID: 25527261 PMCID: PMC4279683 DOI: 10.1186/s12866-014-0306-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 11/24/2014] [Indexed: 11/17/2022] Open
Abstract
Background Bacillus thuringiensis GabR is a Sigma 54-dependent transcriptional activator containing three typical domains, an N-terminal regulatory domain Per-ARNT-Sim (PAS), a central AAA+ (ATPases associated with different cellular activities) domain and a C-terminal helix-turn-helix (HTH) DNA binding domain. GabR positively regulates the expression of the gabT gene of the gab gene cluster, which is responsible for the γ-aminobutyric acid (GABA) shunt. Results Purified GabR was shown to specifically bind to a repeat region that mapped 58 bp upstream of the gabT start codon. The specific signal factors GABA and succinic semialdehyde (SSA) activated gabT expression, whereas GABA- and SSA-inducible gabT transcription was abolished in sigL and gabR mutants. GABA and SSA did not induce the expression of either SigL or GabR. Deletion of the PAS domain of GabR resulted in increased gabT transcriptional activity, both in the presence and absence of GABA. Conclusions This study identified the GabR-binding site on the gabT promoter; however, GabR does not bind to its own promoter. gabT transcription is induced by GABA and SSA, and inducible expression is dependent on SigL and activated by GabR. The PAS domain in GabR is repressing its enhancer transcriptional activity on the gabT promoter. Repression is released upon GABA addition, whereupon transcription is induced. Electronic supplementary material The online version of this article (doi:10.1186/s12866-014-0306-3) contains supplementary material, which is available to authorized users.
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Navas LE, Berretta MF, Pérez MP, Amadio AF, Ortiz EM, Sauka DH, Benintende GB, Zandomeni RO. Sequence and Expression of Two cry8 Genes from Bacillus thuringiensis INTA Fr7-4, a Native Strain from Argentina. J Mol Microbiol Biotechnol 2014; 24:241-8. [DOI: 10.1159/000365929] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Division of labour and terminal differentiation in a novel Bacillus thuringiensis strain. ISME JOURNAL 2014; 9:286-96. [PMID: 25083932 DOI: 10.1038/ismej.2014.122] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2014] [Revised: 05/12/2014] [Accepted: 06/11/2014] [Indexed: 11/08/2022]
Abstract
A major challenge in bacterial developmental biology has been to understand the mechanisms underlying cell fate decisions. Some differentiated cell types display cooperative behaviour. Cooperation is one of the greatest mysteries of evolutionary biology and microbes have been considered as an excellent system for experimentally testing evolution theories. Bacillus thuringiensis (Bt) is a spore-forming bacterium, which is genetically closely related to B. anthracis, the agent of anthrax, and to B. cereus, an opportunistic human pathogen. The defining feature that distinguishes Bt from its relatives is its ability to produce crystal inclusions in the sporulating cells. These toxins are solubilized after ingestion and are cooperative public goods in insect hosts. In this study, we describe a Bt strain LM1212 that presents the unique ability to terminally differentiate into crystal producers and spore formers. Transcriptional analysis based on lacZ and gfp reporter genes suggested that this phenotype is the consequence of a new type of cell differentiation associated with a novel regulation mode of cry gene expression. The differentiating crystal-producer phenotype has higher spore productivity than a typical Bt strain and is better able to compete with Cry toxin null 'cheaters'. Potentially, this division of labour provides additional fitness benefits in terms of spore viability or durability of Cry toxin.
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Deng C, Peng Q, Song F, Lereclus D. Regulation of cry gene expression in Bacillus thuringiensis. Toxins (Basel) 2014; 6:2194-209. [PMID: 25055802 PMCID: PMC4113751 DOI: 10.3390/toxins6072194] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 07/11/2014] [Accepted: 07/15/2014] [Indexed: 02/02/2023] Open
Abstract
Bacillus thuringiensis differs from the closely related Bacillus cereus group species by its ability to produce crystalline inclusions. The production of these crystals mainly results from the expression of the cry genes, from the stability of their transcripts and from the synthesis, accumulation and crystallization of large amounts of insecticidal Cry proteins. This process normally coincides with sporulation and is regulated by various factors operating at the transcriptional, post-transcriptional, metabolic and post-translational levels.
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Affiliation(s)
- Chao Deng
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
| | - Qi Peng
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
| | - Fuping Song
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
| | - Didier Lereclus
- INRA, UMR1319 Micalis, La Minière, Guyancourt 78280, France.
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Screening of cry-type promoters with strong activity and application in Cry protein encapsulation in a sigK mutant. Appl Microbiol Biotechnol 2014; 98:7901-9. [PMID: 24928660 DOI: 10.1007/s00253-014-5874-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 05/15/2014] [Accepted: 05/24/2014] [Indexed: 10/25/2022]
Abstract
To optimize the expression of cry genes in a Bacillus thuringiensis sigK mutant failing in crystal releasing, the transcriptional activity of the cry promoters cry1A, cry3A, cry4A, and cry8E was compared using lacZ gene fusions. A beta-galactosidase assay indicated that the cry8E promoter showed the highest transcriptional activity. A novel Escherichia coli-B. thuringiensis shuttle vector pHT315-8E21b was constructed for cry gene expression using the cry8E promoter and the multiple cloning sites from vector pET21b, based on vector pHT315. SDS-PAGE analysis showed that the expression of the cry1Ac gene directed by the cry8E promoter was increased by approximately 2.4-fold over the expression directed by the cry3A promoter. The cry1Ba gene was expressed in the sigK mutant with the constructed vector pHT315-8E21b. Normal bipyramidal crystals encapsulated in mother cell were observed by transmission electron microscopy (TEM). The encapsulated Cry1Ba protein expressed in the sigK mutant showed activity against Ostrinia furnacalis and Plutella xylostella similar to that of the released Cry1Ba protein expressed in the acrystalliferous strain HD73 and can be protected from inactivation by UV light. All these results suggest that the cry8E promoter can be an efficient transcriptional element for cry gene expression in sigK mutants and can be utilized for the construction of a genetically engineered strain.
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Transcription of the lysine-2,3-aminomutase gene in the kam locus of Bacillus thuringiensis subsp. kurstaki HD73 is controlled by both σ54 and σK factors. J Bacteriol 2014; 196:2934-43. [PMID: 24914178 DOI: 10.1128/jb.01675-14] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lysine 2,3-aminomutase (KAM; EC 5.4.3.2) catalyzes the interconversion of l-lysine and l-β-lysine. The transcription and regulation of the kam locus, including lysine-2,3-aminomutase-encoding genes, in Bacillus thuringiensis were analyzed in this study. Reverse transcription-PCR (RT-PCR) analysis revealed that this locus forms two operons: yodT (yodT-yodS-yodR-yodQ-yodP-kamR) and kamA (kamA-yokU-yozE). The transcriptional start sites (TSSs) of the kamA gene were determined using 5' rapid amplification of cDNA ends (RACE). A typical -12/-24 σ(54) binding site was identified in the promoter PkamA, which is located upstream of the kamA gene TSS. A β-galactosidase assay showed that PkamA, which directs the transcription of the kamA operon, is controlled by the σ(54) factor and is activated through the σ(54)-dependent transcriptional regulator KamR. The kamA operon is also controlled by σ(K) and regulated by the GerE protein in the late stage of sporulation. kamR and kamA mutants were prepared by homologous recombination to examine the role of the kam locus. The results showed that the sporulation rate in B. thuringiensis HD(ΔkamR) was slightly decreased compared to that in HD73, whereas that in HD(ΔkamA) was similar to that in HD73. This means that other genes regulated by KamR are important for sporulation.
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Jia Y, Zhao C, Wang Q, Shu C, Feng X, Song F, Zhang J. A genetically modified broad-spectrum strain of Bacillus thuringiensis toxic against Holotrichia parallela, Anomala corpulenta and Holotrichia oblita. World J Microbiol Biotechnol 2013; 30:595-603. [DOI: 10.1007/s11274-013-1470-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 08/23/2013] [Indexed: 11/28/2022]
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Transcriptional regulation and characteristics of a novel N-acetylmuramoyl-L-alanine amidase gene involved in Bacillus thuringiensis mother cell lysis. J Bacteriol 2013; 195:2887-97. [PMID: 23603740 DOI: 10.1128/jb.00112-13] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Bacillus thuringiensis, a novel N-acetylmuramoyl-L-alanine amidase gene (named cwlB) was detected, and the CwlB protein was purified and characterized. Reverse transcription-PCR (RT-PCR) results indicated that cwlB and an upstream gene (named cwlA) formed one transcriptional unit. 5' rapid amplification of cDNA ends (5'-RACE)-PCR and transcriptional fusions with the lacZ gene indicated that transcription of the operon was directed by a promoter, P(cwlA), which is located upstream from the cwlA gene and that the transcription start site is a single 5'-end nucleotide residue T located 25 nucleotides (bp) upstream from the cwlA translational start codon. Moreover, the activity of P(cwlA) was controlled by σ(K). Morphological analysis suggested that the mutation of cwlB could delay spore release compared to the timing of spore release in the wild-type strain. Western blot assay demonstrated that purified CwlB bound to the B. thuringiensis cell wall. Observations with laser confocal microscopy and a green fluorescent protein-based reporter system demonstrated that the CwlB protein localizes to the cell envelope. All results suggest that the CwlB protein is involved in mother cell lysis in B. thuringiensis.
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