Willey J, Schwedock J, Losick R
Biological Laboratories, Harvard University, Cambridge, Massachusetts 02138.
Genes Dev. 1993 May;7(5):895-903. doi: 10.1101/gad.7.5.895.
The formation of an aerial mycelium by the filamentous bacterium Streptomyces coelicolor is determined in part by a small morphogenetic protein called SapB. A collection of representative bald (bld) mutants, which are blocked in aerial mycelium formation, are all defective in the production of this protein and regain the capacity to undergo morphological differentiation when SapB is supplied exogenously. We now report that most of the bld mutants are rescued for SapB production and aerial mycelium formation when grown near certain other bld mutants. Extracellular complementation experiments of this kind indicate that morphological differentiation is governed by a hierarchical cascade of at least four kinds of intercellular signals. At least one such signal is present in conditioned medium. It is resistant to boiling and protease treatment, and it remains effective even when diluted up to eightfold in fresh medium.
丝状细菌天蓝色链霉菌气生菌丝体的形成部分由一种名为SapB的小形态发生蛋白决定。一组典型的秃头（bld）突变体在气生菌丝体形成过程中受阻，它们在这种蛋白质的产生上均存在缺陷，当外源提供SapB时，它们恢复了进行形态分化的能力。我们现在报告，当大多数bld突变体在某些其他bld突变体附近生长时，其SapB产生和气生菌丝体形成得到了挽救。这种细胞外互补实验表明，形态分化受至少四种细胞间信号的分级级联调控。至少有一种这样的信号存在于条件培养基中。它对煮沸和蛋白酶处理具有抗性，即使在新鲜培养基中稀释至八倍仍保持有效。
