Biochemical evidence against protein-mediated uptake of myristic acid in the bioluminescent marine bacterium Vibrio harveyi.
The bioluminescent marine bacterium, Vibrio harveyi, can utilize exogenous myristic acid (14:0) for beta-oxidation, phospholipid and lipid A synthesis, and as an source of myristyl aldehyde for light emission in the V. harveyi dark mutant M17. A variety of genetic and biochemical strategies were employed in an attempt to isolate V. harveyi mutants defective in myristate uptake and to characterize proteins involved in this process. Although [3H]myristate uptake in a tritium suicide experiment decreased the survival of nitrosoguanidine-treated M17 cells by a factor of 10(5), none of the surviving cells characterized were defective in either incorporation of exogenous myristate into phospholipid or stimulation of light emission. These parameters were also unaffected when intact M17 cells were treated with proteases. Moreover, M17 double mutants selected on the basis of diminished luminescence response to myristate all incorporated [3H]myristate into lipids normally. Finally, no resistant colonies were obtained using the bacteriocidal fatty acid analogue, 11-bromoundecanoate, and experiments with decanoate (10:0) indicated that the V. harveyi cell envelope is very sensitive to physical disruption by fatty acids. Taken together, these results support an unfacilitated uptake of myristic acid in V. harveyi, in contrast with the regulated vectorial transport and activation of long chain fatty acids in Escherichia coli.
Byers
David M
DM
The Atlantic Research Centre, Department of Pediatrics, Dalhousie University, C-305, Clinical Research Centre, 5849 University Avenue, Halifax, NS B3H 4H7, Canada. david.byers@dal.ca
Shen
Zhiwei
Z
D001692:Biological Transport; D003470:Culture Media; D005227:Fatty Acids / Q000032:analysis; D008163:Luminescent Measurements; D009154:Mutation; D009227:Myristic Acids / Q000378:metabolism*; D009604:Nitrosoguanidines / Q000494:pharmacology; D010447:Peptide Hydrolases / Q000378:metabolism; D010743:Phospholipids / Q000096:biosynthesis; D014733:Vibrio / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D014871:Water Microbiology
D003470:Culture Media; D005227:Fatty Acids; D009227:Myristic Acids; D009604:Nitrosoguanidines; D010743:Phospholipids; D010447:Peptide Hydrolases