Georgiou C D, Fang H, Gennis R B
J Bacteriol. 1987 May;169(5):2107-12. doi: 10.1128/jb.169.5.2107-2112.1987.
The aerobic respiratory chain of Escherichia coli contains two terminal oxidases which are differentially regulated. The cytochrome o complex predominates under growth conditions of high aeration, whereas the cytochrome d complex predominates when the oxygen tension is low. Either terminal oxidase will support aerobic growth. The goal of the work presented in this paper was to identify genes required for the expression of the functional form of the cytochrome d complex, other than the genes encoding the polypeptide components of the oxidase complex (cyd locus). A strain lacking the cytochrome o complex (cyo mutant strain) was mutagenized by using a lambda-Mu hybrid hopper bacteriophage, lambda placMu53, which inserts randomly into the chromosome and carries a kanamycin resistance marker. Strains were isolated and examined which were unable to grow aerobically, i.e., which lacked functional cytochrome d complex, and which could not be complemented by introduction of the cyd gene on F-prime episomes. One strain was selected for characterization. The phage insert was mapped to min 18.9 on the genetic linkage map, defining a new genetic locus, cydC. Evidence described in the text suggests that the gene product is probably required for the synthesis of the unique heme d component of the cytochrome d complex.
大肠杆菌的有氧呼吸链包含两种受不同调控的末端氧化酶。细胞色素o复合物在高通气生长条件下占主导，而细胞色素d复合物在氧张力低时占主导。任何一种末端氧化酶都能支持有氧生长。本文所呈现工作的目标是鉴定除了编码氧化酶复合物多肽组分的基因（cyd位点）之外，细胞色素d复合物功能形式表达所需的基因。通过使用λ-Mu杂交跳跃噬菌体λplacMu53对缺乏细胞色素o复合物的菌株（cyo突变株）进行诱变，该噬菌体随机插入染色体并携带卡那霉素抗性标记。分离并检测了不能进行有氧生长的菌株，即缺乏功能性细胞色素d复合物且不能通过在F-prime附加体上引入cyd基因进行互补的菌株。选择了一个菌株进行表征。噬菌体插入片段在遗传连锁图上定位到18.9分钟处，定义了一个新的基因位点cydC。文中所述证据表明该基因产物可能是细胞色素d复合物独特的血红素d组分合成所必需的。
