Isolation and characterization of a catalase-peroxidase gene from the pathogenic fungus, Penicillium marneffei
Isolation and characterization of a catalase-peroxidase gene from the pathogenic fungus, Penicillium marneffei
复制标题
DOI：
10.1080/13693780400007144
复制
发表时间：
2005-08-01
期刊：
影响因子：
2.9
通讯作者：
Vanittanakom, N
中科院分区：
文献类型：
--
作者：
Pongpom, P;Cooper, CR;Vanittanakom, N
马尔尼菲青霉菌是一种兼性胞内致病菌，在东南亚国家的艾滋病患者中引起常见的机会性感染。病原体通常可以在巨噬细胞的吞噬体内存活和复制，也可以在血涂片或宿主组织中发现。在肺泡巨噬细胞内存活是马尔尼菲肺孢子虫成功侵入的关键。然而，在这种环境中的氧化应激下的生存机制尚未阐明。从马尔尼菲青霉酵母相cDNA文库中克隆了一个抗原性过氧化氢酶-过氧化物酶蛋白编码基因（cpeA）。该基因的DNA序列分析揭示了一个开放阅读框架，编码一个748个氨基酸的多肽，预测分子量为82.4 kDa。推导的氨基酸序列与许多细菌和真菌的过氧化氢酶-过氧化物酶的氨基酸序列有45 - 69%的同源性。在肽序列中发现了潜在的铁调节结合元件和保守的过氧化物酶活性位点。Southern印迹分析表明，马尔尼菲青霉基因组含有一个拷贝的cpeA。该基因表现出高水平的表达，特别是当温度转移到37摄氏度时被诱导，该温度是形成马尔尼菲假单胞菌的致病酵母相的条件。cpeA mRNA转录物在37 ℃下的高表达可能有助于这种二型真菌在宿主细胞中的存活。
Penicillium marneffei is a facultative intracellular pathogen that causes common opportunistic infection in AIDS patients in Southeast Asian countries. The pathogen can usually survive and replicate inside the phagosome of macrophages, and is also found extracellularly in blood smears or host tissue. Surviving within the alveolar macrophage is a primary key to the success of P. marneffei invasion. However, the mechanism of survival under oxidative stress in this environment has not been elucidated. An antigenic catalase-peroxidase protein-encoding gene ( cpeA) was isolated by antibody screening of a cDNA library derived from the yeast phase of P. marneffei. DNA sequence analysis of this gene revealed an open reading frame encoding a 748 amino acid polypeptide with a predicted molecular mass of 82.4 kDa. The deduced amino acid sequence was 45 - 69% identical to that of catalase-peroxidases from many bacteria and fungi. Potential iron regulated binding elements and conserved active sites for peroxidases were found in the peptide sequence. Southern blot analysis showed that the P. marneffei genome contained a single copy of the cpeA. This gene displayed a high level of expression, specifically being induced when the temperature was shifted to 37 degrees C, the condition whereby the pathogenic yeast phase of P. marneffei is formed. The high expression of the cpeA mRNA transcripts at 37 degrees C may contribute to the survival of this dimorphic fungus in host cells.