THE ROLE OF 4-HYDROXYPHENYLPYRUVATE DIOXYGENASE IN ENHANCEMENT OF SOLID-PHASE ELECTRON TRANSFER BY SHEWANELLA ONEIDENSIS MR-1

Journal Article · Fri Jun 01 04:00:00 EDT 2007 · environmental microbiology

OSTI ID:910167

Turick, C; Amy Ekechukwu, A

While mechanistic details of dissimilatory metal reduction are far from being understood, it is postulated that the electron transfer to solid metal oxides is mediated by outer membrane-associated c-type cytochromes and redox active electron shuttling compounds. This study focuses on the production of homogensitate in Shewanella oneidensis MR-1, an intermediate of tyrosine degradation pathway, which is a precursor of a redox cycling metabolite, pyomelanin. In this study, we determined that two enzymes involved in this pathway, 4-hydroxyphenylpyruvate dioxygenase (4HPPD) and homogentisate 1,2-dioxygenase are responsible for homogentisate production and oxidation, respectively. Inhibition of 4-HPPD activity with the specific inhibitor sulcotrione (2-(2-chloro-4-methane sulfonylbenzoyl)-1,3-cyclohexanedione), and deletion of melA, a gene encoding 4-HPPD, resulted in no pyomelanin production by S. oneidensis MR-1. Conversely, deletion of hmgA which encodes the putative homogentisate 1,2-dioxygenase, resulted in pyomelanin overproduction. The efficiency and rates, with which MR-1 reduces hydrous ferric oxide, were directly linked to the ability of mutant strains to produce pyomelanin. Electrochemical studies with whole cells demonstrated that pyomelanin substantially increases the formal potential (E{sup o}{prime}) of S. oneidensis MR-1. Based on this work, environmental production of pyomelanin likely contributes to an increased solid-phase metal reduction capacity in Shewanella oneidensis.

• Research Organization: SRS
• Sponsoring Organization: DOE
• DOE Contract Number: AC09-96SR18500
• OSTI ID: 910167
• Report Number(s): WSRC-STI-207-00301
• Journal Information: environmental microbiology, Journal Name: environmental microbiology; ISSN 1462-2912
• Publisher: pubinfo
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CAPACITY
CYTOCHROMES
EFFICIENCY
ELECTRON TRANSFER
ELECTRONS
ENZYMES
GENES
MUTANTS
OXIDATION
OXIDES
PRECURSOR
PRODUCTION
STRAINS
TYROSINE