Srinivas G, Vennison S J, Sudha S N, Balasubramanian P, Sekar V
Department of Molecular Microbiology, School of Biotechnology, Madurai Kamaraj University, India.
Appl Environ Microbiol. 1997 Jul;63(7):2792-7. doi: 10.1128/aem.63.7.2792-2797.1997.
In sporulating cultures of Bacillus thuringiensis subsp. yunnanensis HD977, two cell types are observed: cells forming only spores and cells forming only crystals. Curing analysis suggested that the crystal proteins are plasmid encoded. Through plasmid transfer experiments, it was established that a 103-MDa plasmid is involved in the crystal production. Conjugal transfer of this plasmid to Cry- recipient cells of Bacillus thuringiensis subsp. kurstaki HD73-26 conferred the ability to produce crystals exclusively on asporogenous cells of the recipient, indicating that the 103-MDa plasmid mediates the unique regulation of Cry protein production. When the dipteran-specific cryIVB gene was introduced into wild-type (Cry+) and Cry- backgrounds of B. thuringiensis subsp. yunnanensis by phage CP51ts45-mediated transduction, similar to all other B. thuringiensis strains, irregular crystals of CryIVB protein were produced by spore-forming cells in both backgrounds. However, the synthesis of the bipyramidal inclusions of B. thuringiensis subsp. yunnanensis was still limited only to asporogenous cells of the transductant. Thus, it appears that the unique property of exclusive crystal formation in asporogenous cells of B. thuringiensis subsp. yunnanensis is associated with the crystal protein gene(s) per se or its cis acting elements. As the crystals in B. thuringiensis subsp. yunnanensis were formed only in asporogenous cells, attempts were made to find out whether crystal formation had any inhibitory effect on sporulation. It was observed that both Cry+ and Cry- strains of B. thuringiensis subsp. yunnanensis (HD977 and HD977-1, respectively) exhibited comparable sporulation efficiencies. In addition, the Cry- B. thuringiensis subsp. kurstaki host (HD73-26) and its Cry+ transconjugant (HD73-26-16), expressing the B. thuringiensis subsp. yunnanensis crystal protein, were also comparable in their sporulation efficiencies, indicating that production of the crystal proteins of B. thuringiensis subsp. yunnanensis does not affect the process of sporulation.
在苏云金芽孢杆菌云南亚种HD977的芽孢形成培养物中，观察到两种细胞类型：仅形成芽孢的细胞和仅形成晶体的细胞。消除分析表明晶体蛋白由质粒编码。通过质粒转移实验确定，一个103-MDa的质粒参与晶体的产生。将该质粒接合转移到苏云金芽孢杆菌库尔斯塔克亚种HD73-26的Cry-受体细胞中，赋予了受体的无芽孢细胞仅产生晶体的能力，这表明103-MDa的质粒介导了Cry蛋白产生的独特调控。当通过噬菌体CP51ts45介导的转导将双翅目特异性cryIVB基因导入苏云金芽孢杆菌云南亚种的野生型（Cry+）和Cry-背景中时，与所有其他苏云金芽孢杆菌菌株相似，在两种背景下形成芽孢的细胞均产生了不规则的CryIVB蛋白晶体。然而，苏云金芽孢杆菌云南亚种的双金字塔形内含物的合成仍然仅局限于转导子的无芽孢细胞。因此，苏云金芽孢杆菌云南亚种无芽孢细胞中独特的仅形成晶体的特性似乎与晶体蛋白基因本身或其顺式作用元件有关。由于苏云金芽孢杆菌云南亚种中的晶体仅在无芽孢细胞中形成，因此尝试探究晶体形成是否对芽孢形成有任何抑制作用。观察到苏云金芽孢杆菌云南亚种的Cry+和Cry-菌株（分别为HD977和HD977-1）表现出相当的芽孢形成效率。此外，表达苏云金芽孢杆菌云南亚种晶体蛋白的Cry-苏云金芽孢杆菌库尔斯塔克亚种宿主（HD73-26）及其Cry+转接合子（HD73-26-16）在芽孢形成效率方面也相当，这表明苏云金芽孢杆菌云南亚种晶体蛋白的产生不影响芽孢形成过程。
