Expression of the Bacillus thuringiensis vip3A Insecticidal Toxin Gene Is Activated at the Onset of Stationary Phase by VipR, an Autoregulated Transcription Factor

被引:0
作者
Chen, Haibo [1 ,2 ]
Verplaetse, Emilie [1 ]
Slamti, Leyla [1 ]
Lereclus, Didier [1 ]
机构
[1] Univ Paris Saclay, Micalis Inst, INRAE, AgroParisTech, Jouy En Josas, France
[2] Xiangnan Univ, Sch Basic Med Sci, Chenzhou, Hunan, Peoples R China
来源
MICROBIOLOGY SPECTRUM | 2022年 / 10卷 / 04期
关键词
Bacillus; biopesticide; gene regulation; plasmid; transcription; BORDER MEMBRANE-VESICLES; CRYSTAL PROTEINS; VIRULENCE; BINDING; SPORULATION; SUBTILIS; PLASMID; REGULON; TRANSFORMATION; INITIATION;
D O I
10.1128/spectrum.01205-22
中图分类号
Q93 [微生物学];
学科分类号
071005 ; 100705 ;
摘要
The Vegetative insecticidal protein Vip3A is produced by some Bacillus thuringiensis strains from the mid-log growth phase to sporulation. Although Vip3A is important for the entomopathogenicity of B. thuringiensis, the vip3A gene regulation is unknown. In the B. thuringiensis serovar kurstaki HD1 strain, vip3A is carried by the pBMB299 plasmid, which is absent in the closely related strain B. thuringiensis kurstaki HD73. Using a transcriptional fusion between the vip3A promoter and lacZ, we observed that the HD73 strain is unable to express vip3A. This result suggests that a specific regulator is required for vip3A expression. Assuming that the regulator gene is located on the same plasmid as vip3A, we transferred pBMB299 from the HD1 strain to the HD73 strain. We found that Vip3A was produced in the HD73 strain containing pBMB299, suggesting that the regulator gene is located on this plasmid. Using this heterologous host and promoter-lacZ transcription fusions, we showed that a specific regulator, VipR, is essential to activate vip3A expression at the onset of stationary phase. We demonstrated that vipR transcription is positively autoregulated and the determination of the vipR and vip3A promoters pinpointed a putative VipR target upstream from the Sigma A-specific -10 region of these two promoters. Surprisingly, this conserved sequence was also found upstream of cry1I and cry2 genes. Finally, we showed that vip3A and vipR expression is increased drastically in a Dspo0A mutant unable to initiate sporulation. In conclusion, we have characterized a novel regulator involved in the entomopathogenic potency of B. thuringiensis through a sporulation-independent pathway. IMPORTANCE The insecticidal properties of Bacillus thuringiensis are due mainly to Cry toxins which form a crystalline inclusion during sporulation. However, other proteins participate in the pathogenicity of the bacterium, notably, the Vip3A toxins that are produced from vegetative growth to sporulation. The VipR regulator that activates vip3A gene expression at the onset of stationary phase is positively autoregulated, and an analysis of the promoter region of the vip3A and vipR genes reveals the presence of a highly conserved DNA sequence. This possible VipR target sequence is also found upstream of the cry2A and cry1I genes, suggesting that Cry toxins can be produced before the bacteria enter sporulation. Such a result could allow us to better understand the role of Cry and Vip3A toxins during the B. thuringiensis infectious cycle in insects, in addition to the primary role of the Cry toxins in the toxemia caused by ingestion of crystals.
引用
收藏
页数:17
相关论文
共 57 条
  • [1] STRUCTURAL AND FUNCTIONAL-ANALYSIS OF THE PROMOTER REGION INVOLVED IN FULL EXPRESSION OF THE CRYIIIA TOXIN GENE OF BACILLUS-THURINGIENSIS
    AGAISSE, H
    LERECLUS, D
    [J]. MOLECULAR MICROBIOLOGY, 1994, 13 (01) : 97 - 107
  • [2] REGULATION OF INSECTICIDAL CRYSTAL PROTEIN-PRODUCTION IN BACILLUS-THURINGIENSIS
    BAUM, JA
    MALVAR, T
    [J]. MOLECULAR MICROBIOLOGY, 1995, 18 (01) : 1 - 12
  • [3] BRADFORD MM, 1976, ANAL BIOCHEM, V72, P248, DOI 10.1016/0003-2697(76)90527-3
  • [4] INITIATION OF SPORULATION IN BACILLUS-SUBTILIS IS CONTROLLED BY A MULTICOMPONENT PHOSPHORELAY
    BURBULYS, D
    TRACH, KA
    HOCH, JA
    [J]. CELL, 1991, 64 (03) : 545 - 552
  • [5] Optimizing pyramided transgenic Bt crops for sustainable pest management
    Carriere, Yves
    Crickmore, Neil
    Tabashnik, Bruce E.
    [J]. NATURE BIOTECHNOLOGY, 2015, 33 (02) : 161 - 168
  • [6] Bacterial Vegetative Insecticidal Proteins (Vip) from Entomopathogenic Bacteria
    Chakroun, Maissa
    Banyuls, Nuria
    Bel, Yolanda
    Escriche, Baltasar
    Ferre, Juan
    [J]. MICROBIOLOGY AND MOLECULAR BIOLOGY REVIEWS, 2016, 80 (02) : 329 - 350
  • [7] Revision of the nomenclature for the Bacillus thuringiensis pesticidal crystal proteins
    Crickmore, N
    Zeigler, DR
    Feitelson, J
    Schnepf, E
    Van Rie, J
    Lereclus, D
    Baum, J
    Dean, DH
    [J]. MICROBIOLOGY AND MOLECULAR BIOLOGY REVIEWS, 1998, 62 (03) : 807 - +
  • [8] A structure-based nomenclature for Bacillus thuringiensis and other bacteria-derived pesticidal proteins
    Crickmore, Neil
    Berry, Colin
    Panneerselvam, Suresh
    Mishra, Ruchir
    Connor, Thomas R.
    Bonning, Bryony C.
    [J]. JOURNAL OF INVERTEBRATE PATHOLOGY, 2021, 186
  • [9] Regulation of cry Gene Expression in Bacillus thuringiensis
    Deng, Chao
    Peng, Qi
    Song, Fuping
    Lereclus, Didier
    [J]. TOXINS, 2014, 6 (07): : 2194 - 2209
  • [10] Gene knockout demonstrates that vip3A contributes to the pathogenesis of Bacillus thuringiensis toward Agrotis ipsilon and Spodoptera exigua
    Donovan, WP
    Donovan, JC
    Engleman, JT
    [J]. JOURNAL OF INVERTEBRATE PATHOLOGY, 2001, 78 (01) : 45 - 51