Ciche T A, Bintrim S B, Horswill A R, Ensign J C
Department of Bacteriology, University of Wisconsin, Madison, WI 53706, USA.
J Bacteriol. 2001 May;183(10):3117-26. doi: 10.1128/JB.183.10.3117-3126.2001.
The bacterium Photorhabdus luminescens is a symbiont of the entomopathogenic nematode Heterorhabditis bacteriophora. The nematode requires the bacterium for infection of insect larvae and as a substrate for growth and reproduction. The nematodes do not grow and reproduce in insect hosts or on artificial media in the absence of viable P. luminescens cells. In an effort to identify bacterial factors that are required for nematode growth and reproduction, transposon-induced mutants of P. luminescens were screened for the loss of the ability to support growth and reproduction of H. bacteriophora nematodes. One mutant, NGR209, consistently failed to support nematode growth and reproduction. This mutant was also defective in the production of siderophore and antibiotic activities. The transposon was inserted into an open reading frame homologous to Escherichia coli EntD, a 4'-phosphopantetheinyl (Ppant) transferase, which is required for the biosynthesis of the catechol siderophore enterobactin. Ppant transferases catalyze the transfer of the Ppant moiety from coenzyme A to a holo-acyl, -aryl, or -peptidyl carrier protein(s) required for the biosynthesis of fatty acids, polyketides, or nonribosomal peptides. Possible roles of a Ppant transferase in the ability of P. luminescens to support nematode growth and reproduction are discussed.
发光光杆状菌是昆虫病原线虫嗜菌异小杆线虫的一种共生菌。线虫感染昆虫幼虫需要这种细菌,并且将其作为生长和繁殖的底物。在没有活的发光光杆状菌细胞的情况下,线虫无法在昆虫宿主体内或人工培养基上生长和繁殖。为了确定线虫生长和繁殖所需的细菌因子,对发光光杆状菌的转座子诱导突变体进行了筛选,以寻找支持嗜菌异小杆线虫生长和繁殖能力丧失的突变体。一个突变体NGR209始终无法支持线虫的生长和繁殖。该突变体在铁载体的产生和抗生素活性方面也存在缺陷。转座子插入到一个与大肠杆菌EntD同源的开放阅读框中,EntD是一种4'-磷酸泛酰巯基乙胺(Ppant)转移酶,是儿茶酚铁载体肠杆菌素生物合成所必需的。Ppant转移酶催化Ppant部分从辅酶A转移到脂肪酸、聚酮化合物或非核糖体肽生物合成所需的全酰基、芳基或肽基载体蛋白上。本文讨论了Ppant转移酶在发光光杆状菌支持线虫生长和繁殖能力方面的可能作用。