Distinct and redundant roles of the two protein kinase A isoforms Tpk1p and Tpk2p in morphogenesis and growth of Candida albicans
Distinct and redundant roles of the two protein kinase A isoforms Tpk1p and Tpk2p in morphogenesis and growth of Candida albicans
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DOI：
10.1046/j.1365-2958.2001.02688.x
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发表时间：
2001-12-01
影响因子：
3.6
通讯作者：
Ernst, JF
中科院分区：
文献类型：
--
作者：
Bockmühl, DP;Krishnamurthy, S;Ernst, JF
TPK1和TPK2编码白念珠菌蛋白激酶A(PKA)催化亚基的两种亚型。缺乏TPK1等位基因的突变体在固体诱导培养基上菌丝形态发生有缺陷，而在液体菌丝诱导培养基上，菌丝形态发生受到轻微影响。相反，tpk2突变体在固体培养中只有部分形态发生缺陷，而在液体中观察到强烈的阻断。此外，酵母形式的tpk2-而不是tpk1-突变体在入侵琼脂中完全缺乏。由于Tpk1p和Tpk2p的N-末端结构域不同，约80-90个氨基酸，而催化部分高度同源，因此我们测试了具有交换N-末端结构域的杂交Tpk蛋白的功能。结果表明，催化部分介导了Tpk蛋白的丝状化特异性，而琼脂侵袭是由Tpk2p的N-末端结构域介导的。纯合的tpk1和tpk2突变株生长正常；然而，含有单一可调节的TPK1等位基因(PCK1p-TPK1)的tpk2突变株在低表达水平时严重生长缺陷。它的菌丝形态发生完全受阻，对高渗透压或温度具有抗逆性。因此，白念珠菌中的两种Tpk亚型都有共同的生长功能，但与酿酒酵母不同的是，它们在不同环境中对细丝形成具有积极的、特定的作用。
TPK1 and TPK2 encode both isoforms of protein kinase A (PKA) catalytic subunits in Candida albicans. Mutants lacking both TPK1 alleles showed defective hyphal morphogenesis on solid inducing media, whereas in liquid hypha, formation was affected slightly. In contrast, tpk2 mutants were only partially morphogenesis defective on solid media, whereas a strong block was observed in liquid. In addition, the yeast forms of tpk2- but not tpk1- mutants were completely deficient in invading agar. Because Tpk1p and Tpk2p differ in their N-terminal domains of approximately 80-90 amino acids, while the catalytic portions are highly homologous, the functions of hybrid Tpk proteins with exchanged N-terminal domains were tested. The results demonstrate that the catalytic portions mediate Tpk protein specificities with regard to filamentation, whereas agar invasion is mediated by the N-terminal domain of Tpk2p. Homozygous tpk1 and tpk2 mutants grew normally; however, a tpk2 mutant strain containing a single regulatable TPK1 allele (PCK1p-TPK1) at low expression levels was severely growth defective. It was completely blocked in hyphal morphogenesis and was stress resistant to high osmolarities or temperatures. Thus, both Tpk isoforms in C. albicans share growth functions but, unlike Saccharomyces cerevisiae isoforms, they have positive, specific roles in filament formation in different environments.