Cloning and sequence of cymA a gene encoding a tetraheme cytochrome c required for reduction of iron(III), fumarate, and nitrate by Shewanella putrefaciens MR-1
Cloning and sequence of cymA a gene encoding a tetraheme cytochrome c required for reduction of iron(III), fumarate, and nitrate by Shewanella putrefaciens MR-1
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DOI：
10.1128/jb.179.4.1143-1152.1997
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发表时间：
1997-02-01
影响因子：
3.2
通讯作者：
Myers, JM
中科院分区：
文献类型：
--
作者：
Myers, CR;Myers, JM
编码四血红素细胞色素 c 的 cymA 基因是从腐败希瓦氏菌 MR-1 中克隆的。该基因补充了在 cymA 中插入 TnphoA 且缺乏铁 (III)、硝酸盐、富马酸盐和锰 (IV) 呼吸还原作用的突变体。 cymA的561 bp核苷酸序列编码187个氨基酸的蛋白质，预测分子量为20.8 kDa，没有明显的N端信号序列；与此一致的是，在野生型中检测到大小为 21 kDa 的细胞色素，但在插入突变体中不存在。 cymA基因转录成mRNA；主要转录本约为 790 个碱基，表明它不是多顺反子操纵子的一部分，在 cymA 突变体中未检测到该 RNA 转录本，在 MR-I 的细胞质膜和可溶部分中发现了 CymA 蛋白，并且它与来自其他细菌的多血红素 C 型细胞色素具有部分氨基酸序列同源性，这些细胞色素是 表面上参与电子从细胞质膜到周质受体的转移，富马酸和铁(III)还原酶分别定位到MR-1的周质和外膜，表明CymA可能具有类似的电子转移作用。
The cymA gene, which encodes a tetraheme cytochrome c, was cloned from Shewanella putrefaciens MR-1. This gene complemented a mutant which had a TnphoA insertion in cymA and which was deficient in the respiratory reduction of iron(III), nitrate, fumarate, and manganese(IV). The 561-bp nucleotide sequence of cymA encodes a protein of 187 amino acids with a predicted molecular mass of 20.8 kDa, No N-terminal signal sequence was readily apparent; consistent with this, a cytochrome with a size of 21 kDa was detected in the wild type but was absent in the insertional mutant. The cymA gene is transcribed into an mRNA; the major transcript was approximately 790 bases, suggesting that it is not part of a multicistronic operon, This RNA transcript was not detected in the cymA mutant, The CymA protein was found in the cytoplasmic membrane and soluble fraction of MR-I, and it shares partial amino acid sequence homology with multiheme c-type cytochromes from other bacteria, These cytochromes are ostensibly involved in the transfer of electrons from the cytoplasmic membrane to accepters in the periplasm, The localization of the fumarate and iron(III) reductases to the periplasm and outer membrane of MR-1, respectively, suggests the possibility of a similar electron transfer role for CymA.