TY - JOUR
T1 - Use of transposon TnphoA to identify genes for cell envelope proteins of Escherichia coli required for long-chain fatty acid transport
T2 - The periplasmic protein Tsp potentiates long-chain fatty acid transport
AU - Azizan, A.
AU - Black, P. N.
PY - 1994
Y1 - 1994
N2 - TnphoA was used to mutagenize the chromosome in an effort to identify membrane-bound and exported components of the long-chain fatty acid transport system of Escherichia coli. This strategy identified three classes of fusions that were unable to grow or grew at reduced rates on minimal agar plates containing the long-chain fatty acid oleate (C(18:1)), (i) fadL-phoA, (ii) tolC-phoA, and (iii) tsp-phoA. fadL-phoA and tolC-phoA fusions were unable to grow on oleate as the sole carbon and energy source, while the tsp-phoA fusion had a markedly reduced growth rate. As expected, fadL-phoA fusions were unable to grow on oleate plates because the outer membrane-bound fatty acid transport protein FadL was defective. The identification of multiple fadL-phoA fusions demonstrated that this strategy of mutagenesis specifically targeted membrane-bound and exported components required for growth on long- chain fatty acids. tolC-phoA fusions were sensitive to fatty acids (particularly medium chain) and thus unable to grow, whereas the reduced growth rate of tsp-phoA fusions on oleate was apparently due to changes in the energized state of the outer membrane or inner membrane. tsp-phoA fusions transported the long-chain fatty acid oleate at only 50% of wild-type levels when cells were energized with 1 mM DL-lactate. Under conditions in which transport was measured in the absence of lactate, tsp-phoA fusion strains and wild-type strains had the same levels of oleate transport. The tsp+ clone pAZA500 was able to restore wild-type transport activity to the tsp-phoA strain under lactate-energized conditions. These results indicate that the periplasmic protein Tsp potentiates long-chain fatty acid transport.
AB - TnphoA was used to mutagenize the chromosome in an effort to identify membrane-bound and exported components of the long-chain fatty acid transport system of Escherichia coli. This strategy identified three classes of fusions that were unable to grow or grew at reduced rates on minimal agar plates containing the long-chain fatty acid oleate (C(18:1)), (i) fadL-phoA, (ii) tolC-phoA, and (iii) tsp-phoA. fadL-phoA and tolC-phoA fusions were unable to grow on oleate as the sole carbon and energy source, while the tsp-phoA fusion had a markedly reduced growth rate. As expected, fadL-phoA fusions were unable to grow on oleate plates because the outer membrane-bound fatty acid transport protein FadL was defective. The identification of multiple fadL-phoA fusions demonstrated that this strategy of mutagenesis specifically targeted membrane-bound and exported components required for growth on long- chain fatty acids. tolC-phoA fusions were sensitive to fatty acids (particularly medium chain) and thus unable to grow, whereas the reduced growth rate of tsp-phoA fusions on oleate was apparently due to changes in the energized state of the outer membrane or inner membrane. tsp-phoA fusions transported the long-chain fatty acid oleate at only 50% of wild-type levels when cells were energized with 1 mM DL-lactate. Under conditions in which transport was measured in the absence of lactate, tsp-phoA fusion strains and wild-type strains had the same levels of oleate transport. The tsp+ clone pAZA500 was able to restore wild-type transport activity to the tsp-phoA strain under lactate-energized conditions. These results indicate that the periplasmic protein Tsp potentiates long-chain fatty acid transport.
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U2 - 10.1128/jb.176.21.6653-6662.1994
DO - 10.1128/jb.176.21.6653-6662.1994
M3 - Article
C2 - 7961418
AN - SCOPUS:0027999821
VL - 176
SP - 6653
EP - 6662
JO - Journal of Bacteriology
JF - Journal of Bacteriology
SN - 0021-9193
IS - 21
ER -