X-ray structure refinement and comparison of three forms of mitochondrial aspartate aminotransferase

McPhalen, Catherine A.; Vincent, M. G.; Jansonius, Johan N.

doi:10.1016/0022-2836(92)90935-d

Cited by 207 publications

(174 citation statements)

References 56 publications

Supporting

Mentioning

166

Contrasting

Order By: Relevance

“…Replacement of Pro-297 with Arg showed that the positive charge had not affected the network of interactions at the active site, nor had it provided an additional anchor for interacting with the γ-carboxy group of -Asp. This, however, might not be an important requirement, because in AATase Arg-292 is brought into the active-site milieu after conformational changes subsequent to binding aspartate [12]. Our results suggest that this mutation is not sufficient to permit the binding of aspartate to P297R (results not shown).…”

Section: Discussionmentioning

confidence: 65%

“…In addition, both the enzymes catalyse decarboxylation, racemization and transamination, for example, apart from their physiological reaction. Site-directed mutagenesis and X-ray crystallographic studies of AATase had identified Arg-386 as the residue binding the α-carboxy group of aspartate, whereas Arg-292 binds the γ-carboxy group [12]. A sequence comparison revealed that Arg-292 of AATase is equivalent to Pro-297 of rSHMT.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Role of Pro-297 in the catalytic mechanism of sheep liver serine hydroxymethyltransferase

Talwar

Leelavathy

Rao

et al. 2000

Biochemical Journal

View full text Add to dashboard Cite

Serine hydroxymethyltransferase belongs to the α class of pyridoxal-5´-phosphate enzymes along with aspartate aminotransferase. Recent reports on the three-dimensional structure of human liver cytosolic serine hydroxymethyltransferase had suggested a high degree of similarity between the active-site geometries of the two enzymes. A comparison of the sequences of serine hydroxymethyltransferases revealed the presence of several highly conserved residues, including Pro-297. This residue is equivalent to residue Arg-292 of aspartate aminotransferase, which binds the γ-carboxy group of aspartate. In an attempt to change the reaction specificity of the hydroxymethyltransferase to that of an aminotransferase and to assign a possible reason for the conserved nature of Pro-297, it was mutated to Arg. The mutation decreased the hydroxymethyltransferase activity significantly (by 85–90%) and abolished the ability to catalyse alternative reactions, without alteration in the oligomeric structure, pyridoxal 5´-phosphate content or substrate binding. However, the concentration of the quinonoid intermediate and the extent of proton exchange was decreased considerably (by approx. 85%) corresponding to the decrease in catalytic activity. Interestingly, mutant Pro-297 Arg was unable to perform the transamination reaction with l-aspartate. All these results suggest that although Pro-297 is indirectly involved in catalysis, it might not have any role in imparting substrate specificity, unlike the similarly positioned Arg-292 in aspartate aminotransferase.

show abstract

Section: Discussionmentioning

confidence: 65%

Section: Introductionmentioning

confidence: 99%

Role of Pro-297 in the catalytic mechanism of sheep liver serine hydroxymethyltransferase

Talwar

Leelavathy

Rao

et al. 2000

Biochemical Journal

View full text Add to dashboard Cite

show abstract

“…In the native dimer, several residues from this peptide are located at the subunit interface and in contact with the Nterminal arm from the other subunit (43). Binding of Hsc70 exclusively to this region of the chain might interfere with formation of the dimer and perhaps even with further folding of the monomer.…”

Section: Discussionmentioning

confidence: 99%

Binding to Chaperones Allows Import of a Purified Mitochondrial Precursor into Mitochondria

Artigues

Iriarte

Martinez‐Carrion

2002

Journal of Biological Chemistry

View full text Add to dashboard Cite

“…With regards to the co-factor-binding pocket in the active site of PLP-dependent enzymes, details of how the different proteins interact with the co-enzyme have been well-defined only in the cases for which high-resolution crystal structures have been determined (Kirsch et al, 1984;Hyde et al, 1988;McPhalen et al, 1992;Antson et al, 1993;Momany et al, 1995b;Toney et al, 1995). In particular, a glycine-rich loop has been recognized at the co-factor binding site in those enzymes for which crystal structures are available and has also been identified through site-directed mutagenesis in threonine and D-serine dehydratases (Dana et al, 1987;Marceau et al, 1990) and more recently in aminolevulinate synthase (Gong et al, 1995(Gong et al, , 1996.…”

Section: Discussionmentioning

confidence: 99%

Mutation of cysteine 111 in Dopa decarboxylase leads to active site perturbation

et al. 1997

View full text Add to dashboard Cite

Cysteine 111 in Dopa decarboxylase (DDC) has been replaced by alanine or serine by site-directed mutagenesis. Compared to the wild-type enzyme, the resultant C111A and C111 S mutant enzymes exhibit kc,, values of about 50% and 15%, respectively, at pH 6.8, while the K, values remain relatively unaltered for L-3,4-dihydroxyphenylalanine (L-Dopa) and L-5-hydroxytryptophan (LJ-HTP). While a significant decrease of the 280 nm optically active band present in the wild type is observed in mutant DDCs, their visible co-enzyme absorption and CD spectra are similar to those of the wild type. With respect to the wild type, the Cys-1 1 ]-+Ala mutant displays a reduced affinity for pyridoxal 5"phosphate (PLP), slower kinetics of reconstitution to holoenzyme, a decreased ability to anchor the external aldimine formed between D-Dopa and the bound co-enzyme, and a decreased efficiency of energy transfer between tryptophan residue(s) and reduced PLP. Values of pK, and pKb for the groups involved in catalysis were determined for the wild-type and the C l l l A mutant enzymes. The mutant showed a decrease in both pK values by about 1 pH unit, resulting in a shift of the pH of the maximum velocity from 7.2 (wild-type) to 6.2 (mutant). This change in maximum velocity is mirrored by a similar shift in the spectrophotometrically determined pK value of the 420 -+ 390 nm transition of the external aldimine. These results demonstrate that the sulfhydryl group of Cys-1 1 1 is catalytically nonessential and provide strong support for previous suggestion that this residue is located at or near the PLP binding site (Dominici P, Maras B, Mei G, Bom Voltattorni C. 1991. Eur JBiochern 201:393-397). Moreover, our findings provide evidence that Cys-111 has a structural role in PLP binding and suggest that this residue is required for maintenance of proper active-site conformation.Keywords: active site; decarboxylase; pyridoxal 5"phosphate; site-directed mutagenesis The versatility of pyridoxal 5"phosphate (PLP) as a co-factor is demonstrated by the wide variety of reactions that enzymes dependent upon it catalyze. Although detailed catalytic mechanisms and information correlating structure and function have been reported for many PLP dependent enzymes, such information is conspicuously lacking for PLP dependent decarboxylases.Even though aromatic amino acid decarboxylases have been cloned from a number of mammalian (Ichinose et al., 1989;Tanaka et al., 1989;Kang & Joh, 1990;Taketoshi et al., 1990), insect (Eveleth et al., 1986, and plant sources (DeLuca et al., 1989;Kawalleck et al., 1993; Facchini & DeLuca, 1994)

show abstract

X-ray structure refinement and comparison of three forms of mitochondrial aspartate aminotransferase

Cited by 207 publications

References 56 publications

Role of Pro-297 in the catalytic mechanism of sheep liver serine hydroxymethyltransferase

Role of Pro-297 in the catalytic mechanism of sheep liver serine hydroxymethyltransferase

Binding to Chaperones Allows Import of a Purified Mitochondrial Precursor into Mitochondria

Mutation of cysteine 111 in Dopa decarboxylase leads to active site perturbation

Contact Info

Product

Resources

About