Mechanism of substrate inhibition in Escherichia coli phosphofructokinase. Academic Article

abstract

• Phosphofructokinase from Escherichia coli (EcPFK) is a homotetramer with four active sites, which bind the substrates fructose-6-phosphate (Fru-6-P) and MgATP. In the presence of low concentrations of Fru-6-P, MgATP displays substrate inhibition. Previous proposals to explain this substrate inhibition have included both kinetic and allosteric mechanisms. We have isolated hybrid tetramers containing one wild type subunit and three mutated subunits (1:3). The mutated subunits contain mutations that decrease affinity for Fru-6-P (R243E) or MgATP (F76A/R77D/R82A) allowing us to systematically simplify the possible allosteric interactions between the two substrates. In the absence of a rate equation to explain the allosteric effects in a tetramer, the data have been compared to simulated data for an allosteric dimer. Since the apparent substrate inhibition caused by MgATP binding is not seen in hybrid tetramers with only a single native MgATP binding site, the proposed kinetic mechanism is not able to explain this phenomenon. The data presented are consistent with an allosteric antagonism between MgATP in one active site and Fru-6-P in a second active site.

authors

• Reinhart, Gregory

published proceedings

• Biochemistry

author list (cited authors)

• Fenton, A. W., & Reinhart, G. D.

citation count

• 16

complete list of authors

• Fenton, Aron W||Reinhart, Gregory D

publication date

• November 2003

publisher

• American Chemical Society (ACS)  Publisher

published in

• Biochemistry  Journal

keywords

• Allosteric Regulation
• Base Sequence
• DNA Primers
• Escherichia Coli
• Kinetics
• Phosphofructokinases
• Substrate Specificity

PubMed Central ID

• 14580215

Digital Object Identifier (DOI)

• 10.1021/bi0349221

start page

• 12676

end page

• 12681

volume

• 42

issue

• 43

URL

• http%3A%2F%2Fdx.doi.org%2F10.1021%2Fbi0349221