Publications

• Glycerol-insensitive Arabidopsis mutants: gli1 seedlings lack glycerol kinase, accumulate glycerol and are more resistant to abiotic stress.

  Eastmond P.J.

  The aim of this study was to investigate the process of glycerol catabolism in germinating Arabidopsis seed. A genetic screen was performed to isolate glycerol-insensitive (gli) mutant seedlings. Three separate mutant loci were identified (gli1, gli2 and gli3). Of these, only gli1 is unable to uti ... >> More

  The aim of this study was to investigate the process of glycerol catabolism in germinating Arabidopsis seed. A genetic screen was performed to isolate glycerol-insensitive (gli) mutant seedlings. Three separate mutant loci were identified (gli1, gli2 and gli3). Of these, only gli1 is unable to utilise glycerol. Following germination, gli1 seedlings transiently accumulate glycerol derived from the breakdown of storage oil and are more resistant to hyperosmotic stress, salt stress, oxidative stress, freezing and desiccation. Enzyme assays revealed that gli1 lacks glycerol kinase activity. GLI1 mapped to chromosome 1 near the putative glycerol kinase gene NHO1. Mutations in this gene were identified in three independent gli1 alleles. A cDNA encoding GLI1 was cloned and its function was proven by complementation of an Escherichia coli glycerol kinase (glpK) deletion strain. Quantitative RT-PCR analysis showed that GLI1 is expressed in all tissues, but is transiently upregulated during early post-germinative growth and leaf senescence. These data show that glycerol kinase is required for glycerol catabolism in Arabidopsis and that the accumulation of glycerol can enhance resistance to a variety of abiotic stresses associated with dehydration. << Less

  Plant J. 37:617-625(2004) [PubMed] [EuropePMC]

• IIA(Glc) allosteric control of Escherichia coli glycerol kinase: binding site cooperative transitions and cation-promoted association by Zinc(II).

  Holtman C.K., Pawlyk A.C., Meadow N., Roseman S., Pettigrew D.W.

  The catalytic activity of glycerol kinase (EC 2.7.1.30, ATP:glycerol 3-phosphotransferase) from Escherichia coli is inhibited allosterically by IIA(Glc) (previously known as III(Glc)), the glucose-specific phosphocarrier protein of the phosphoenolpyruvate:glycose phosphotransferase system. A seque ... >> More

  The catalytic activity of glycerol kinase (EC 2.7.1.30, ATP:glycerol 3-phosphotransferase) from Escherichia coli is inhibited allosterically by IIA(Glc) (previously known as III(Glc)), the glucose-specific phosphocarrier protein of the phosphoenolpyruvate:glycose phosphotransferase system. A sequentially contiguous portion of glycerol kinase undergoes an induced fit conformational change involving coil, alpha-helix, and 3(10)-helix upon IIA(Glc) binding. A second induced fit occurs upon binding of Zn(II) to a novel intermolecular site, which increases complex stability by cation-promoted association. Eight of the ten sequentially contiguous amino acids are substituted with alanine to evaluate the roles of these positions in complex formation. Effects of the substitutions reveal both favorable and antagonistic contributions of the normal amino acids to complex formation, and Zn(II) reverses these contributions for two of the amino acids. The consequences of some of the substitutions for IIA(Glc) inhibition are consistent with changes in the intermolecular interactions seen in the crystal structures. However, for the amino acids that are located in the region that is alpha-helical in the absence of IIA(Glc), the effects of the substitutions are not consistent with changes in intermolecular interactions but with increased stability of the alpha-helical region due to the higher alpha-helix propensity of alanine. The reduced affinity for IIA(Glc) binding seen for these variants is consistent with predictions of Freire and co-workers [Luque, I., and Freire, E. (2000) Proteins: Struct., Funct., Genet. 4, 63-71]. These variants show also increased cation-promoted association by Zn(II) so that the energetic contribution of Zn(II) to complex formation is doubled. The similarity of effects of the alanine substitutions of the amino acids in the alpha-helical region for IIA(Glc) binding affinity and cation-promoted association by Zn(II) indicates that they function as a cooperative unit. << Less

  Biochemistry 40:14302-14308(2001) [PubMed] [EuropePMC]

• Catalytic and allosteric properties of glycerol kinase from Escherichia coli.

  Thorner J.W., Paulus H.

  J. Biol. Chem. 248:3922-3932(1973) [PubMed] [EuropePMC]