Abstract:
:All of the heme-degrading enzymes that have been characterized to date require molecular oxygen as a cosubstrate. Escherichia coli O157:H7 has been shown to express heme uptake and transport proteins, as well as use heme as an iron source. This enteric pathogen colonizes the anaerobic space of the lower intestine in mammals, yet no mechanism for anaerobic heme degradation has been reported. Herein we provide evidence for an oxygen-independent heme-degradation pathway. Specifically, we demonstrate that ChuW is a radical S-adenosylmethionine methyltransferase that catalyzes a radical-mediated mechanism facilitating iron liberation and the production of the tetrapyrrole product we termed "anaerobilin." We further demonstrate that anaerobilin can be used as a substrate by ChuY, an enzyme that is coexpressed with ChuW in vivo along with the heme uptake machinery. Our findings are discussed in terms of the competitive advantage this system provides for enteric bacteria, particularly those that inhabit an anaerobic niche in the intestines.
journal_name
Proc Natl Acad Sci U S Aauthors
LaMattina JW,Nix DB,Lanzilotta WNdoi
10.1073/pnas.1603209113subject
Has Abstractpub_date
2016-10-25 00:00:00pages
12138-12143issue
43eissn
0027-8424issn
1091-6490pii
1603209113journal_volume
113pub_type
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