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Gene fusions with β‐lactamase show that subunit I of the cytochrome bd quinol oxidase from E. coli has nine transmembrane helices with the O 2 reactive site near the periplasmic surface
Author(s) -
Zhang Jie,
Barquera Blanca,
Gennis Robert B
Publication year - 2004
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(04)00125-5
Subject(s) - periplasmic space , transmembrane domain , transmembrane protein , escherichia coli , cytochrome , topology (electrical circuits) , respiratory chain , protein subunit , cytochrome c oxidase , gene , oxidase test , biology , chemistry , biochemistry , microbiology and biotechnology , enzyme , receptor , mathematics , combinatorics
The cytochrome bd quinol oxidase is a component of the respiratory chain of many prokaryotes. The enzyme contains two subunits, CydA and CydB, which were initially predicted based on the sequence of the Escherichia coli oxidase to have seven and eight transmembrane spans, respectively. More recently, the topological model of CydA was revised to predict nine transmembrane helices, based on additional sequence information from other organisms. In the current work, the topology of the E. coli oxidase was experimentally examined using β‐lactamase gene fusions. The results confirm the revised topology, which places the oxygen reactive site near the periplasmic surface.