The two isoforms of the cAMP-dependent protein kinase catalytic subunit are involved in the control of dimorphism in the human fungal pathogen Candida albicans
The two isoforms of the cAMP-dependent protein kinase catalytic subunit are involved in the control of dimorphism in the human fungal pathogen Candida albicans
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DOI：
10.1016/s1087-1845(02)00520-0
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发表时间：
2003-02-01
影响因子：
3
通讯作者：
Cantore, ML
中科院分区：
文献类型：
--
作者：
Cloutier, M;Castilla, R;Cantore, ML
我们克隆了白念珠菌TPK2基因，编码cAMP依赖的蛋白激酶(PKA)催化亚基，并产生了一个tpk2纯合子缺失突变体，以评估其在液体介质中发芽的能力。在tpk2菌株中，N-乙酰氨基葡萄糖(GlcNAc)诱导的胚管形成被减弱，并被已知增加原位PKA活性的化合物增强。在耐热的PKA抑制剂(MyR-PKI)的存在下，萌发被完全阻止。这些结果表明，在缺乏TPK2基因的情况下，TPKI在调节白色念珠菌的形态发生转变方面发挥了积极的作用。我们能够在野生型和tpk2缺失突变细胞中从第二种形式的PKA中鉴定出mRNA。我们发现，缺失TPK2基因的突变体的PKA活性约为野生型的10%。Tpk2缺失突变体在低血清浓度下对血清的萌发反应严重减弱，这表明在低血清浓度下PKA水平是丝状菌生长的重要决定因素。在较高的血清浓度(5%)下，野生型和tpk2缺失突变株的萌发程度相似，表明在这些条件下，萌发是通过不依赖PKA的途径触发的。(C)2002年埃尔塞维尔科学公司(美国)。版权所有。
We have cloned the Candida albicans TPK2 gene encoding a cAMP-dependent protein kinase (PKA) catalytic subunit and generated a tpk2 homozygous null mutant to assess its ability to germinate in liquid media. N-acetylglucosamine (GlcNAc)-induced germ-tube formation was attenuated in the tpk2 strain and enhanced by compounds that are known to increase the PKA activity in situ. Germination was completely blocked in the presence of the myristoylated derivative of the heat-stable PKA inhibitor (Myr-PKI). These results indicate that TPKI acts positively in regulating the morphogenetic transition in C albicans in the absence of the TPK2 gene. We were able to identify an mRNA from this second form of PKA in both wild-type and tpk2 null mutant cells. We found that PKA activity measured in the mutant lacking the TPK2 gene was about 10% of that displayed by the wild-type. The finding that the germinative response of tpk2 null mutant to serum was severely diminished at low serum concentrations indicates that the level of PKA is an important determinant of filamentous growth at low serum concentrations. The extent of germination attained at higher serum concentrations (5%) was similar in the wild-type and in the tpk2 null mutant strains suggesting that under these conditions germination was triggered through a PKA-independent pathway. (C) 2002 Elsevier Science (USA). All rights reserved.