Yeast chitin synthases 1 and 2 consist of a non-homologous and dispensable N-terminal region and of a homologous moiety essential for function
Yeast chitin synthases 1 and 2 consist of a non-homologous and dispensable N-terminal region and of a homologous moiety essential for function
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DOI：
10.1007/bf02173007
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发表时间：
1996-09-25
期刊：
影响因子：
--
通讯作者：
Cabib, E
中科院分区：
文献类型：
--
作者：
Ford, RA;Shaw, JA;Cabib, E
真菌甲壳素合成酶的预测蛋白质序列可以分为一个非同源的N-末端区域和一个在不同的合成酶之间具有显著同源性的C-末端区域。我们通过构建一系列从酿酒酵母CHS1和CHS2基因两端延伸的嵌套缺失来探索这些结构域的功能。在这两种情况下，编码非同源N-末端区域的大部分或全部序列(Chs1p的蛋白质的三分之一和Chs2p的约四分之一)都可以被切除，而对相应合成酶的体外活性或体内功能几乎没有影响。然而，同源区的进一步微小缺失(20-25个氨基酸)对酶的活性和功能是有害的，并经常导致酶的产酶性质的改变。同样，C端相对较小的缺失(约75个氨基酸)会导致两种合酶的酶活性和功能丧失。因此，膜定位、酶活性和功能所需的所有信息似乎都存在于Chs1p和Chs2p的同源区，这种情况也适用于其他几丁质合成酶。
Predicted protein sequences of fungal chitin synthases can be divided into a non-homologous N-terminal region and a C-terminal region that shows significant homology among the various synthases. We have explored the function of these domains by constructing a series of nested deletions, extending from either end, in the CHS1 and CHS2 genes of Saccharomyces cerevisiae. In both cases, most or all of the sequences encoding the non-homologous N-terminal region (one-third of the protein for Chs1p and about one-fourth for Chs2p) could be excised, with little effect on the enzymatic activity in vitro of the corresponding synthase or on its function in vivo. However, further small deletions (20-25 amino acids) into the homologous region were deleterious to enzymatic activity and function., and often led to changes in the zymogenic character of the enzymes. Similarly, relatively small (about 75 amino acids) deletions from C-terminus resulted in loss of enzymatic activity and function of both synthases. Thus, it appears that all the information necessary for membrane localization, enzymatic activity and function resides in the homologous regions of Chs1p and Chs2p, a situation that may also apply to other chitin synthases.