SapB and the chaplins:: connections between morphogenetic proteins in Streptomyces coelicolor
SapB and the chaplins:: connections between morphogenetic proteins in Streptomyces coelicolor
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DOI：
10.1111/j.1365-2958.2007.05674.x
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发表时间：
2007-05-01
影响因子：
3.6
通讯作者：
Elliot, Marie A.
中科院分区：
文献类型：
--
作者：
Capstick, David S.;Willey, Joanne M.;Elliot, Marie A.
链霉菌的形态发生特征是与基质相关的营养菌丝分化成向上生长的气生菌丝。这种转变需要bld基因的活性和生物表面活性剂的分泌，降低菌落-空气界面的表面张力，使新生气生菌丝能够出现。天蓝色链霉菌产生两类表面活性分子，SapB和卓别林。虽然这两种分子都是重要的气生发育，没有什么是已知的功能冗余或这些表面活性剂的相互作用，除了观察气生菌丝的形成可以通过以下两种途径之一进行：一个SapB依赖的途径，当细胞生长在丰富的培养基和一个SapB独立的途径，利用不足的碳源，如甘露醇。我们使用突变体分析表明，虽然卓别林是重要的，但不是必需的，丰富的培养基上的发展，他们是必不可少的MS（大豆粉甘露醇）培养基上的分化，和相应的发育缺陷可以抑制的SapB的存在。此外，产生的卓别林条件bld突变体在气生菌丝形成时，生长在允许的培养基，MS，这表明以前未表征的SapB-独立的途径是卓别林依赖。与此相反，bld突变体在所有媒体上的气生形态发生受阻，既不SapB也不卓别林。最后，我们表明，构建的无效突变体，缺乏所有的卓别林和SapB生物合成基因未能在任何生长条件下分化。我们建议，生物表面活性剂活性的SapB和卓别林是必不可少的丰富的培养基上正常的气生菌丝的形成，而卓别林的生物合成和分泌单独驱动气生形态发生MS培养基。
Morphogenesis in the streptomycetes features the differentiation of substrate-associated vegetative hyphae into upwardly growing aerial filaments. This transition requires the activity of bld genes and the secretion of biosurfactants that reduce the surface tension at the colony-air interface enabling the emergence of nascent aerial hyphae. Streptomyces coelicolor produces two classes of surface-active molecules, SapB and the chaplins. While both molecules are important for aerial development, nothing is known about the functional redundancy or interaction of these surfactants apart from the observation that aerial hyphae formation can proceed via one of two pathways: a SapB-dependent pathway when cells are grown on rich medium and a SapB-independent pathway on poorly utilized carbon sources such as mannitol. We used mutant analysis to show that while the chaplins are important, but not required, for development on rich medium, they are essential for differentiation on MS (soy flour mannitol) medium, and the corresponding developmental defects could be suppressed by the presence of SapB. Furthermore, the chaplins are produced by conditional bld mutants during aerial hyphae formation when grown on the permissive medium, MS, suggesting that the previously uncharacterized SapB-independent pathway is chaplin dependent. In contrast, a bld mutant blocked in aerial morphogenesis on all media makes neither SapB nor chaplins. Finally, we show that a constructed null mutant that lacks all chaplin and SapB biosynthetic genes fails to differentiate in any growth condition. We propose that the biosurfactant activities of both SapB and the chaplins are essential for normal aerial hyphae formation on rich medium, while chaplin biosynthesis and secretion alone drives aerial morphogenesis on MS medium.