title: Turnover of the 4'-phosphopantetheine prosthetic group of acyl carrier protein.
abstract: Acyl carrier protein is an essential cofactor in fatty acid biosynthesis, and in contrast to the stability of the protein moiety during growth, its 4'-phosphopantetheine prosthetic group is metabolically active. The biosynthetic incorporation of deuterium into nonexchangeable positions of acyl carrier protein was found to enhance the sensitivity of the protein to pH-induced hydrodynamic expansion. This constitutional isotope effect was exploited to separate deuterated from normal acyl carrier protein by conformationally sensitive gel electrophoresis, thus providing the analytical framework for separating pre-existing (deuterated) from newly synthesized acyl carrier protein in pulse-chase experiments. The rate of acyl carrier protein prosthetic group turnover was found to depend on the intracellular concentration of coenzyme A. At low coenzyme A levels, prosthetic group turnover was four times faster than the rate of new acyl carrier protein biosynthesis but at the higher coenzyme A concentrations characteristic of logarithmic growth, turnover was an order of magnitude slower, amounting to approximately 25% of the acyl carrier protein pool per generation. These observations suggest that the acyl carrier protein prosthetic group turnover cycle may be related to coenzyme A metabolism rather than to lipid biosynthesis.
mesh_terms: D000213:Acyl Carrier Protein / Q000302:isolation & purification / Q000378:metabolism*; D000409:Alanine / Q000378:metabolism; D004926:Escherichia coli / Q000254:growth & development / Q000378:metabolism*; D007700:Kinetics; D010204:Pantetheine / Q000031:analogs & derivatives / Q000378:metabolism*; D013045:Species Specificity; D013438:Sulfhydryl Compounds / Q000378:metabolism*
chemical_list: D000213:Acyl Carrier Protein; D013438:Sulfhydryl Compounds; D010204:Pantetheine; C003129:4'-phosphopantetheine; D000409:Alanine