Pishko E J, Kirkland T N, Cole G T
Department of Botany, University of Texas, Austin 78713, USA.
Gene. 1995 Dec 29;167(1-2):173-7. doi: 10.1016/0378-1119(95)00654-0.
Two chitinase (CTS)-encoding genes (cts) from Coccidioides immitis (Ci), a respiratory fungal pathogen of humans, were cloned and sequenced. Both the genomic and cDNA sequences are presented. The transcription start points and poly(A)-addition sites were confirmed. The cts1 gene contains five introns and a 1281-bp ORF which translates a 427-amino-acid (aa) protein of 47.4 kDa. The cts2 gene contains two introns and a 2580-bp ORF which translates a 860-aa protein of 91.4 kDa. The deduced CTS1 protein showed highest homology to the Aphanocladium album and Trichoderma harzianum CTS (74% and 76%, respectively), while CTS2 showed highest homology to the CTS of Saccharomyces cerevisiae (Sc) and Candida albicans (47% and 51%, respectively). The putative N-terminal sequence of the mature CTS1 protein also showed 89% homology to the reported N-terminal sequence of a 48-kDa complement fixation antigen (CF-Ag) of Ci which has demonstrated chitinase activity. The CF-Ag is a clinically important antigen used in serodiagnosis of this fungal disease. CTS2 showed several of the conserved features of the Sc CTS, including putative catalytic and Ser/Thr-rich domains, and a C-terminal Cys-rich region. We propose that CTS1 and CTS2 of Ci are members of two distinct classes of fungal chitinases, an observation not previously reported for a single fungus.
从人类呼吸道真菌病原体球孢子菌（Coccidioides immitis，Ci）中克隆并测序了两个编码几丁质酶（CTS）的基因（cts）。同时给出了基因组序列和cDNA序列。确定了转录起始点和聚腺苷酸化位点。cts1基因包含5个内含子和一个1281 bp的开放阅读框（ORF），该开放阅读框编码一个47.4 kDa的427个氨基酸（aa）的蛋白质。cts2基因包含2个内含子和一个2580 bp的ORF，该开放阅读框编码一个91.4 kDa的860个氨基酸的蛋白质。推导的CTS1蛋白与白附球菌（Aphanocladium album）和哈茨木霉（Trichoderma harzianum）的CTS同源性最高（分别为74%和76%），而CTS2与酿酒酵母（Saccharomyces cerevisiae，Sc）和白色念珠菌（Candida albicans）的CTS同源性最高（分别为47%和51%）。成熟CTS1蛋白的推定N端序列与已报道的具有几丁质酶活性的Ci 48 kDa补体固定抗原（CF-Ag）的N端序列也显示出89%的同源性。CF-Ag是该真菌疾病血清诊断中一种重要的临床抗原。CTS2显示出Sc CTS的几个保守特征，包括推定的催化结构域和富含丝氨酸/苏氨酸的结构域，以及一个C端富含半胱氨酸的区域。我们认为Ci的CTS1和CTS2是真菌几丁质酶两个不同类别的成员，这一观察结果以前在单一真菌中未见报道。
