1
|
Xu L, Han G, Fan X, Lv J, Zhang X, Peng Q, Zhang J, Xu J, Song F. Characteristics of the sigK Deletion Mutant from Bacillus thuringiensis var. israelensis Strain Bt-59. Curr Microbiol 2020; 77:3422-3429. [PMID: 32770390 DOI: 10.1007/s00284-020-02150-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 07/28/2020] [Indexed: 11/26/2022]
Abstract
All major insecticidal genes of Bacillus thuringiensis var. israelensis (Bti) are controlled by the sporulation-specific sigma factor Sigma E (sigE), while sigE is negatively regulated by Sigma K (sigK). Therefore, knocking out sigK plays an important role in regulating the expression of insecticidal genes in Bti. A sigK deletion mutant of B. thuringiensis var. israelensis strain Bt-59, Bt59(ΔsigK), was constructed by homologous recombination and characterized. The sigK deletion resulted in no mature spores and delayed mother cell lysis from T25 to T60, while the genetically complemented strain, Bt59(HFsigK), had mother cell lysis at T25. Compared to Bt-59, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis indicated that the expression of Cry4Aa2/4Ba1 and Cyt1Aa1 proteins in Bt59(ΔsigK) increased approximately 1.67 and 1.21 times, respectively. However, there was no significant change in Cry11Aa1 protein expression between the two strains. Bioassay results showed that the sigK deletion mutation slightly reduced the insecticidal activity of Bt-59 against Culex pipiens pallens and did not obviously affect activity against Aedes albopictus.
Collapse
Affiliation(s)
- Linghuan Xu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
- Department of Applied Microbiology, Jiangsu Lixiahe District Institute of Agricultural Sciences, Yangzhou, 225007, China
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, 225002, China
| | - Guangjie Han
- Department of Applied Microbiology, Jiangsu Lixiahe District Institute of Agricultural Sciences, Yangzhou, 225007, China
| | - Xintong Fan
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - 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
| | - 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
| | - Jian Xu
- Department of Applied Microbiology, Jiangsu Lixiahe District Institute of Agricultural Sciences, Yangzhou, 225007, China.
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, 225002, 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.
| |
Collapse
|
2
|
Sakano Y, Park HW, Bideshi DK, Ge B, Federici BA. Contributions of 5'-UTR and 3'-UTR cis elements to Cyt1Aa synthesis in Bacillus thuringiensis subsp. israelensis. J Invertebr Pathol 2017; 149:66-75. [PMID: 28782510 DOI: 10.1016/j.jip.2017.08.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 07/17/2017] [Accepted: 08/01/2017] [Indexed: 11/15/2022]
Abstract
The biopesticide used most effectively to control mosquito and blackfly vectors of human diseases worldwide is Bacillus thuringiensis subsp. israelensis. The high efficacy of this bacterium is due to synergistic interactions among four protein entomotoxins assembled individually into a single parasporal body (PB) during sporulation. Cyt1Aa, the primary synergist, is the most abundant toxin, comprising approximately 55% of the PB's mass. The other proteins are Cry11Aa at ∼35%, and Cry4Aa and Cry4Ba, which together account for the remaining ∼10%. The molecular genetic basis for the comparatively large amount of Cyt1Aa synthesized is unknown. Here, in addition to the known strong BtI (σE) and BtII (σK) promoters, we demonstrate a third promoter (BtIII) that has high identity to the σE promoter of Bacillus subtilis, contributes to the large amount of Cyt1Aa synthesized. We also show that a cyt1Aa-BtIII construct was not functional in a σE-deficient strain of B. subtilis. Comparison of transcription levels and protein profiles for recombinant strains containing different combinations of BtI, BtII and BtIII, or each promoter alone, showed that BtIII is active throughout sporulation. We further demonstrate that a stable stem-loop in the 3'-untranslated region (3'-UTR, predicted ΔG=-27.6) contributes to the high level of Cyt1Aa synthesized.
Collapse
Affiliation(s)
- Yuko Sakano
- Department of Entomology, University of California, Riverside, Riverside, CA 92521, United States
| | - Hyun-Woo Park
- Department of Entomology, University of California, Riverside, Riverside, CA 92521, United States; Department of Biological Sciences, California Baptist University, Riverside, CA 92504, United States.
| | - Dennis K Bideshi
- Department of Entomology, University of California, Riverside, Riverside, CA 92521, United States; Department of Biological Sciences, California Baptist University, Riverside, CA 92504, United States
| | - Baoxue Ge
- Interdepartmental Graduate Program in Genetics, Genomics, and Bioinformatics, University of California, Riverside, Riverside, CA 92521, United States
| | - Brian A Federici
- Department of Entomology, University of California, Riverside, Riverside, CA 92521, United States; Interdepartmental Graduate Program in Genetics, Genomics, and Bioinformatics, University of California, Riverside, Riverside, CA 92521, United States
| |
Collapse
|
3
|
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.
Collapse
|
4
|
Identification of a catabolite-responsive element necessary for regulation of the cry4A gene of Bacillus thuringiensis subsp. israelensis. J Bacteriol 2009; 191:4687-92. [PMID: 19465665 DOI: 10.1128/jb.00421-09] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacillus thuringiensis subsp. israelensis produces a potent mosquitocidal protein, Cry4A. We have identified a 15-bp catabolite responsive element (cre), overlapping the -35 element of the cry4A promoter. Changing a guanine to adenine at position -49 in the promoter abolished glucose catabolite repression of cry4A and enhanced promoter activity two- to threefold. This cis regulatory element is essential for controlled toxin synthesis, vital to evolutionary success of B. thuringiensis subsp. israelensis.
Collapse
|
5
|
Khan SR, Banerjee-Bhatnagar N. Loss of catabolite repression function of HPr, the phosphocarrier protein of the bacterial phosphotransferase system, affects expression of the cry4A toxin gene in Bacillus thuringiensis subsp. israelensis. J Bacteriol 2002; 184:5410-7. [PMID: 12218029 PMCID: PMC135351 DOI: 10.1128/jb.184.19.5410-5417.2002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
HPr, the phosphocarrier protein of the bacterial phosphotransferase system, mediates catabolite repression of a number of operons in gram-positive bacteria. In order to participate in the regulatory process, HPr is activated by phosphorylation of a conserved serine-46 residue. To study the potential role of HPr in the regulation of Cry4A protoxin synthesis in Bacillus thuringiensis subsp. israelensis, we produced a catabolite repression-negative mutant by replacing the wild-type copy of the ptsH gene with a mutated copy in which the conserved serine residue of HPr was replaced with an alanine. HPr isolated from the mutant strain was not phosphorylated at Ser-45 by HPr kinase, but phosphorylation at His-14 was found to occur normally. The enzyme I and HPr kinase activities of the mutant were not affected. Analysis of the B. thuringiensis subsp. israelensis mutant harboring ptsH-S45A in the chromosome showed that cry4A expression was derepressed from the inhibitory effect of glucose. The mutant strain produced both cry4A and sigma(35) gene transcripts 4 h ahead of the parent strain, but there was no effect on sigma(28) synthesis. In wild-type B. thuringiensis subsp. israelensis cells, cry4A mRNA was observed from 12 h onwards, while in the mutant it appeared at 8 h and was produced for a longer period. The total amount of cry4A transcripts produced by the mutant was higher than by the parent strain. There was a 60 to 70% reduction in the sporulation efficiency of the mutant B. thuringiensis subsp. israelensis strain compared to the wild-type strain.
Collapse
Affiliation(s)
- Sharik R Khan
- Centre For Biotechnology, Jawaharlal Nehru University. International Centre For Genetic Engineering and Biotechnology, New Delhi, India
| | | |
Collapse
|
6
|
Komano T, Takabe S, Sakai H. Transcription of the insecticidal crystal protein genes of Bacillus thuringiensis. BIOTECHNOLOGY ANNUAL REVIEW 2000; 5:131-54. [PMID: 10874999 DOI: 10.1016/s1387-2656(00)05034-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Production of a large amount of insecticidal crystal proteins encoded on large plasmids is largely dependent upon the mother cell, Bacillus thuringiensis (B. thuringiensis, also Bt), specific transcription systems attributable to sporulation. In the middle stages of sporulation, cry4A is most actively transcribed from the promoter cry4A-P1. The proximal transcriptional start point of cry4A, which is under the control of the promoter P1, is used in Bacillus subtilis (B. subtilis) in the middle stage of sporulation. The nucleotide sequence that determines the cry4A-P1 promoter is homologous to the consensus sequence for the promoter of sigma E-specific genes in B. subtilis, and to those promoters of the insecticidal protein genes that are efficiently transcribed in vitro with the RNA polymerase E sigma 35 isolated from B. thuringiensis. The sigma factor sigma 35 of B. thuringiensis is highly homologous and functionally equivalent to sigma E of B. subtilis. These results suggest that the cry4A transcription from P1 is under the control of sigma E in B. subtilis, and under the control of sigma 35 in B. thuringiensis.
Collapse
Affiliation(s)
- T Komano
- Department of Genetic Engineering, Faculty of Biology-oriented Science and Technology, Kinki University, Wakayama, Japan.
| | | | | |
Collapse
|
7
|
Zhang J, Schairer HU, Schnetter W, Lereclus D, Agaisse H. Bacillus popilliae cry18Aa operon is transcribed by sigmaE and sigmaK forms of RNA polymerase from a single initiation site. Nucleic Acids Res 1998; 26:1288-93. [PMID: 9469839 PMCID: PMC147395 DOI: 10.1093/nar/26.5.1288] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Bacillus popilliae is an obligate pathogen for larvae of the insect family Scarabaeidae (Coleoptera). It forms parasporal crystals upon sporulation. The gene cry18Aa coding for the parasporal crystal protein and an upstream open reading frame, orf1, were previously isolated from B.popilliae. Here we report an analysis of cry18Aa transcription in Bacillus thuringiensis. The only transcriptional start site of cry18Aa was found 29 bp upstream of the open reading frame orf1, suggesting that orf1 and cry18Aa are transcribed as an operon. lacZ fusion to the cry18Aa promoter was used to follow the time-course of cry18Aa transcription in wild type B.thuringiensis and in various B.thuringiensis sporulation-deficient mutants (spo0A, sigE or sigK). In wild type B.thuringiensis, the cry18Aa promoter was activated 2 h after the end of exponential growth and the expression lasted to the late sporulation phase. The results of promoter activity in Spo+or Spo-backgrounds together with the results of primer extension experiments suggest that the transcription from this promoter can be driven by both sigmaE and sigmaK types of RNA polymerase at a single start site. The promoter region of cry18Aa operon fits the consensus sequences of both sigmaE and sigmaK dependent promoters of Bacillus.
Collapse
Affiliation(s)
- J Zhang
- Zentrum für Molekularbiologie Heidelberg and Zoologisches Institut, Universität Heidelberg, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany.
| | | | | | | | | |
Collapse
|
8
|
Delécluse A, Barloy F, Rosso ML. Les bactéries pathogènes des larves de diptères: structure et spécificité des toxines. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/s0924-4204(97)86391-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|