期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 108, 期 28, 页码 11393-11398出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1104922108
关键词
oligomerization; Pho regulon; phosphonic acid
资金
- Danish Council for Independent Research, Natural Sciences
- Natural Sciences and Engineering Research Council of Canada (NSERC)
- Danish National Research Foundation
Organophosphonate utilization by Escherichia coli requires the 14 cistrons of the phnCDEFGHIJKLMNOP operon, of which the carbon-phosphorus lyase has been postulated to consist of the seven polypeptides specified by phnG to phnM. A 5,660-bp DNA fragment encompassing phnGHIJKLM is cloned, followed by expression in E. coli and purification of Phn-polypeptides. PhnG, PhnH, PhnI, PhnJ, and PhnK copurify as a protein complex by ion-exchange, size-exclusion, and affinity chromatography. The five polypeptides also comigrate in native-PAGE. Cross-linking of the purified protein complex reveals a close proximity of PhnG, PhnI, PhnJ, and PhnK, as these subunits disappear concomitant with the formation of large cross-linked protein complexes. Two molecular forms are identified, a major form of molecular mass of approximately 260 kDa, a minor form of approximately 640 kDa. The stoichiometry of the protein complex is suggested to be PhnG(4)H(2)I(2)J(2)K. Deletion of individual phn genes reveals that a strain harboring plasmid-borne phnGHIJ produces a protein complex consisting of PhnG, PhnH, PhnI, and PhnJ, whereas a strain harboring plasmid-borne phnGIJK produces a protein complex consisting of PhnG and PhnI. We conclude that phnGHIJK specify a soluble multisubunit protein complex essential for organophosphonate utilization.
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