Heme-Biosynthetic Porphobilinogen Deaminase Protects Aspergillus nidulans from Nitrosative Stress
Heme-Biosynthetic Porphobilinogen Deaminase Protects Aspergillus nidulans from Nitrosative Stress
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DOI：
10.1128/aem.06195-11
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发表时间：
2011-10
影响因子：
4.4
通讯作者：
Shengmin Zhou;Toshiaki Narukami;Misuzu Nameki;T. Ozawa;Yosuke Kamimura;T. Hoshino;N. Takaya
中科院分区：
文献类型：
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作者：
Shengmin Zhou;Toshiaki Narukami;Misuzu Nameki;T. Ozawa;Yosuke Kamimura;T. Hoshino;N. Takaya
微生物已经发展出对抗活性氮（RNS）的机制；然而，只有少数涉及的真菌基因已被表征。在这里，我们通过引入在多拷贝载体中构建的基因组DNA文库，从真菌转化体中筛选抗rns的中性曲霉菌株。我们发现AN0121.3基因（hemC）编码一种类似于血红素生物合成酶卟啉胆素原脱氨酶（PBG-D）的蛋白质，并促进耐rns真菌的生长。毛竹中PBG-D的过量产生促进了对RNS的耐受性，而PBG-D的抑制导致生长对RNS过敏。PBG-D水平与细胞原血红素合成、黄血红蛋白（FHb；由fhbA和fhbB编码）和亚硝酸盐还原酶（NiR；由niiA编码）活性相当。FHb和NiR都是分别消耗一氧化氮和亚硝酸盐的血红蛋白，我们发现它们是RNS存在下最大生长所必需的。RNS可上调hemC的转录。这些结果表明，PBG-D是一种新的NO耐受蛋白，通过FHb和NiR调节环境NO和亚硝酸盐水平的降低。
ABSTRACT Microorganisms have developed mechanisms to combat reactive nitrogen species (RNS); however, only a few of the fungal genes involved have been characterized. Here we screened RNS-resistant Aspergillus nidulans strains from fungal transformants obtained by introducing a genomic DNA library constructed in a multicopy vector. We found that the AN0121.3 gene (hemC) encodes a protein similar to the heme biosynthesis enzyme porphobilinogen deaminase (PBG-D) and facilitates RNS-tolerant fungal growth. The overproduction of PBG-D in A. nidulans promoted RNS tolerance, whereas PBG-D repression caused growth that was hypersensitive to RNS. PBG-D levels were comparable to those of cellular protoheme synthesis as well as flavohemoglobin (FHb; encoded by fhbA and fhbB) and nitrite reductase (NiR; encoded by niiA) activities. Both FHb and NiR are hemoproteins that consume nitric oxide and nitrite, respectively, and we found that they are required for maximal growth in the presence of RNS. The transcription of hemC was upregulated by RNS. These results demonstrated that PBG-D is a novel NO-tolerant protein that modulates the reduction of environmental NO and nitrite levels by FHb and NiR.