Characterization of long-chain fatty acid uptake in <Emphasis Type="Italic">Caulobacter crescentus</Emphasis> |
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Authors: | Fred Zalatan Paul Black |
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Institution: | (1) Department of Biology, State University of New York College at Oneonta, Oneonta, NY 13820, USA;(2) Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE, USA |
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Abstract: | Studies evaluating the uptake of long-chain fatty acids in Caulobacter crescentus are consistent with a protein-mediated process. Using oleic acid (C18:1) as a substrate, fatty acid uptake was linear for
up to 15 min. This process was saturable giving apparent Vmax and Km values of 374 pmol oleate transported/min/mg total protein and 61 μM oleate, respectively, consistent with the notion that
one or more proteins are likely involved. The rates of fatty acid uptake in C. crescentus were comparable to those defined in Escherichia coli. Uncoupling the electron transport chain inhibited oleic acid uptake, indicating that like the long-chain fatty acid uptake
systems defined in other gram-negative bacteria, this process is energy-dependent in C. crescentus. Long-chain acyl CoA synthetase activities were also evaluated to address whether vectorial acylation represented a likely
mechanism driving fatty acid uptake in C. crescentus. These gram-negative bacteria have considerable long-chain acyl CoA synthetase activity (940 pmol oleoyl CoA formed/min/mg
total protein), consistent with the notion that the formation of acyl CoA is coincident with uptake. These results suggest
that long-chain fatty acid uptake in C. crescentus proceeds through a mechanism that is likely to involve one or more proteins. |
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