Sburlati A, Cabib E
J Biol Chem. 1986 Nov 15;261(32):15147-52.
Strains containing a disrupted structural gene for chitin synthetase (chs1::URA3) are defective in chitin synthetase 1 (Chs1) activity but contain normal amounts of chitin (Bulawa, C.E., Slater, M., Cabib, E., Au-Young, J., Sburlati, A., Adair, L., and Robbins, P. W. (1986) Cell 46, 213-225). We have now detected in such strains a new chitin synthetase activity (Chs2), at levels about 5% of those of Chs1 in wild-type cells. Thus, Chs2 is presumably the physiological agent for chitin deposition in strains with a disrupted CHS1 gene and probably also in wild-type strains. Chs1 and Chs2 share certain properties, such as stimulation by N-acetylglucosamine and by partial proteolysis. They differ sharply, however, in divalent cation specificity and in pH optimum. Chs2 also shows less sensitivity than Chs1 to inhibition by polyoxin D or sodium chloride, a property that was used to demonstrate the presence of Chs2 in wild-type extracts. As in the case of Chs1, most of the Chs2 activity was found to be associated with the plasma membranes. This finding, together with the apparent zymogenic nature of Chs2, is consistent with the hypothesis, previously put forward for Chs1, that localized deposition of chitin is attained by activation of the zymogen form at a specific time and place. Function and significance of the two chitin synthetases are discussed in connection with fungal morphogenesis and evolution.
含有几丁质合成酶结构基因破坏（chs1::URA3）的菌株在几丁质合成酶1（Chs1）活性方面存在缺陷，但几丁质含量正常（Bulawa, C.E., Slater, M., Cabib, E., Au-Young, J., Sburlati, A., Adair, L., and Robbins, P. W. (1986) Cell 46, 213 - 225）。我们现在在这类菌株中检测到一种新的几丁质合成酶活性（Chs2），其水平约为野生型细胞中Chs1活性的5%。因此，Chs2可能是CHS1基因破坏的菌株中几丁质沉积的生理介质，可能在野生型菌株中也是如此。Chs1和Chs2具有某些共同特性，如受N - 乙酰葡糖胺和部分蛋白酶水解的刺激。然而，它们在二价阳离子特异性和最适pH方面有显著差异。Chs2对多氧霉素D或氯化钠抑制的敏感性也低于Chs1，这一特性被用于证明野生型提取物中存在Chs2。与Chs1的情况一样，发现大部分Chs2活性与质膜相关。这一发现，连同Chs2明显的酶原性质，与之前针对Chs1提出的假设一致，即几丁质的局部沉积是通过在特定时间和地点激活酶原形式实现的。结合真菌形态发生和进化讨论了两种几丁质合成酶的功能和意义。
