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A new Escherichia coli metabolic competency: growth on fatty acids by a novel anaerobic β‐oxidation pathway
Author(s) -
Campbell John W.,
MorganKiss Rachael M.,
E. Cronan John
Publication year - 2003
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2003.03341.x
Subject(s) - biology , biochemistry , escherichia coli , regulon , anaerobic exercise , mutant , fatty acid , anaerobic respiration , gene , physiology
Summary Escherichia coliuses fatty acids as a sole carbon and energy source during aerobic growth by means of the enzymes encoded by thefadregulon. We report that this bacterium can also grow on fatty acids under anaerobic conditions provided that a terminal respiratory electron acceptor such as nitrate is available. This anaerobic utilization pathway is distinct from the well‐studied aerobic pathway in that (i) it proceeds normally in mutant strains lacking various enzymes of the aerobic pathway; (ii) it functions with fatty acids (octanoate and decanoate) that cannot be used by wild‐typeE. colistrains under aerobic conditions; and (iii) super‐repressor mutants of thefadRregulatory locus that block aerobic growth on fatty acids fail to block the anaerobic pathway. We have identified homologues of the FadA, FadB and FadD proteins required for aerobic fatty acid utilization called YfcY, YfcX and YdiD, respectively, which are involved in anaerobic growth on fatty acids. A strong FadR binding site was detected upstream of theyfcYgene consistent with microarray analyses, indicating thatyfcYXexpression is negatively regulated by FadR under aerobic growth conditions. In contrast, transcriptional regulation ofydiDappears to be independent of FadR, and anaerobic growth on fatty acids is not under FadR control. These three genes are conserved in the available genome sequences of pathogenicE. coli,ShigellaandSalmonella strains.