Calera J A, Choi G H, Calderone R A
Department of Microbiology and Immunology, Georgetown University School of Medicine, Washington, DC 20007-2197, USA.
Yeast. 1998 May;14(7):665-74. doi: 10.1002/(SICI)1097-0061(199805)14:7<665::AID-YEA246>3.0.CO;2-#.
We have cloned and analysed the sequence of a putative histidine kinase, two-component gene (CaHK1) from Candida albicans. This gene encodes a 2471 amino acid protein (Cahk1p) with an estimated molecular mass of 281.8 kDa. A homology search of Cahk1p with other proteins in the databases showed that Cahk1p exhibits the greatest homology at its C-terminus with both the sensor and regulator components of prokaryotic and eukaryotic two-component histidine kinases. A further analysis of this homology showed that the Cahk1p possessed both sensor and regulator domains in the same polypeptide. Also, Cahk1p is likely to be a soluble protein. The sensor kinase domain of Cahk1p contains conserved motifs that are characteristic of all histidine kinase proteins, including the putative histidine which is believed to be autophosphorylated during activation, ATP binding motifs and others (F- and N-motifs), with unknown function. The Cahk1p regulator domain also contains conserved aspartate and lysine residues and the putative aspartate, which is secondarily phosphorylated by the autophosphorylated histidine. Finally, according to the codon usage frequency of the CaHK1 gene in comparison with other genes from C. albicans, there would appear to be a low level of expression of the gene.
我们已经克隆并分析了白色念珠菌中一个假定的组氨酸激酶双组分基因（CaHK1）的序列。该基因编码一个由2471个氨基酸组成的蛋白质（Cahk1p），估计分子量为281.8 kDa。对数据库中Cahk1p与其他蛋白质进行同源性搜索发现，Cahk1p在其C末端与原核和真核双组分组氨酸激酶的传感和调节成分具有最大的同源性。对这种同源性的进一步分析表明，Cahk1p在同一多肽中同时具有传感和调节结构域。此外，Cahk1p可能是一种可溶性蛋白质。Cahk1p的传感激酶结构域包含所有组氨酸激酶蛋白特有的保守基序，包括据信在激活过程中发生自磷酸化的假定组氨酸、ATP结合基序以及其他（F基序和N基序），其功能未知。Cahk1p调节结构域还包含保守的天冬氨酸和赖氨酸残基以及假定的天冬氨酸，它会被自磷酸化的组氨酸进行二次磷酸化。最后，根据CaHK1基因与白色念珠菌其他基因的密码子使用频率比较，该基因的表达水平似乎较低。
