Two regions of the bifunctional protein aspartokinase I- homoserine dehydrogenase I are connected by a short hinge.

Sibilli, Lise; Bras, Gisèle Le; Cohen, Georges N.

doi:10.1016/s0021-9258(19)68606-0

Cited by 14 publications

(4 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A cleavage site yielding a 56-57-kilodalton piece from AK I-HDH I has been already found with a variety of proteases (Veron et al, 1972;Sibilli et al, 1981), and it is not unexpected to observe cleavage at the same site in the present work. Also, as in the case of other proteases, cleavage at this site on one or the two chains does not abolish the dimeric structure.…”

Section: Existence Of Monomeric Kinase and Dehydrogenasesupporting

confidence: 84%

“…This size is compatible with that reported for several NAD-dependent dehydrogenases (Rossmann et al, 1975), including the monomeric octopine dehydrogenase (Olomucki et al, 1972). It is known that the dehydrogenase activity is related to the C-terminal moiety of AK I-HDH I (Veron et al, 1972;Sibilli et al, 1981). The assignment of the homoserine dehydrogenase activity to the C-terminal third of the entire polypeptide chain will be developed below.…”

Section: Existence Of Monomeric Kinase and Dehydrogenasesupporting

confidence: 84%

“…The sites involved in both the kinase and dehydrogenase activities are present in the same chain, albeit in different regions: the kinase activity is carried by the N-terminal moiety and the dehydrogenase activity by the C-terminal moiety (Veron et al, 1972). This has been established by obtaining two smaller fragments endowed with only one of the two activities: limited proteolysis by a variety of proteases (Veron et al, 1972;Sibilli et al, 1981) yields a homodimeric fragment (2 X 56-57 kilodaltons) which has only the dehydrogenase activity, the fragment produced by subtilisin having the same C-terminal end as AK I-HDH I (Veron et al, 1972); on the other hand, another fragment (4 X 53 kilodaltons) (Janin et al, 1967;Sibilli et al, 1982) with the same N-terminal end as AK I-HDH I can be extracted from an ochre mutant (Theze & Saint-Girons, 1974) and possesses only the kinase activity (Veron et al, 1972). These two fragments correspond to partially overlapping segments of the original polypeptide chain, and it has not been possible yet to derive a set of nonoverlapping fragments from AK I-HDH I.…”

mentioning

confidence: 99%

See 2 more Smart Citations

A triglobular model for the polypeptide chain of aspartokinase I-homoserine dehydrogenase I of Escherichia coli

Fazel¹,

Müller²,

G³

et al. 1983

Biochemistry

View full text Add to dashboard Cite

Limited proteolysis of aspartokinase I-homoserine dehydrogenase I from Escherichia coli by type VI protease from Streptomyces griseus yields five proteolytic fragments, three of which are dimeric, the other two being monomeric. One of the monomeric fragments (27 kilodaltons) exhibits residual aspartokinase activity, while the second one (33 kilodaltons) possesses residual homoserine dehydrogenase activity. The smallest of the dimeric species (2 X 25 kilodaltons) is inactive; the two other dimers exhibit either only homoserine dehydrogenase activity (2 X 59 kilodaltons) or both activities (hybrid fragment, 89 + 59 kilodaltons). This characterization of the proteolytic species in terms of molecular weight, subunit structure, and activity leads to the proposal of a triglobular model for the native enzyme. In addition, the time course of the formation of the various fragments was followed by measuring enzymatic activity and performing gel electrophoretic analysis of the protein mixture at defined time intervals during proteolysis. On the basis of the results of these studies, a reaction scheme describing the succession of events during proteolysis is given.

show abstract

Section: Existence Of Monomeric Kinase and Dehydrogenasesupporting

confidence: 84%

Section: Existence Of Monomeric Kinase and Dehydrogenasesupporting

confidence: 84%

mentioning

confidence: 99%

See 1 more Smart Citation

A triglobular model for the polypeptide chain of aspartokinase I-homoserine dehydrogenase I of Escherichia coli

Fazel¹,

Müller²,

G³

et al. 1983

Biochemistry

View full text Add to dashboard Cite

show abstract

“…The extent of reactivation was determined after 1 h for the kinase and by extrapolation to infinite time (Garel & Dautry-Varsat, 1980a) for the dehydrogenase. of 7-10 residues (Sibilli et al, 1981). The same slow pairing reaction occurs in AK-HDH and its AK fragment and could thus be due to the relative movements of these two compact regions connected by a short flexible hinge (residues 292-301).…”

Section: The Slow Reactivationmentioning

confidence: 90%

Mechanism of renaturation of a large protein, aspartokinase-homoserine dehydrogenase

Vaucheret¹,

Signon²,

Bras³

et al. 1987

Biochemistry

View full text Add to dashboard Cite

The renaturation of aspartokinase-homoserine dehydrogenase and of some of its smaller fragments has been investigated after complete unfolding by 6 M guanidine hydrochloride. Fluorescence measurements show that a major folding reaction occurs rapidly (in less than a few seconds) after the protein has been transferred to native conditions and results in the shielding of the tryptophan residues from the aqueous solvent; this step also takes place in the fragments and probably corresponds to the independent folding of different segments along the polypeptide chain. The reappearance of the kinase activity, which is an index of the formation of "native" structure within a single chain, is much slower (a few minutes) and has the following properties: it is involved in a kinetic competition with the formation of aggregates; it has an activation energy of 22 +/- 5 kcal/mol; it is not related to a slow reaction in unfolding and thus probably not controlled by the cis-trans isomerization of X-Pro peptide bonds; its rate is inversely proportional to the solvent viscosity. It seems as if this reaction is limited by the mutual arrangement of the regions that have folded rapidly and independently. It is proposed that the mechanism where a fast folding of domains is followed by a slow pairing of folded domains could be generalized to other long chains composed of several domains; such a slow pairing of folded domains would correspond to a rate-limiting process specific to the renaturation of large proteins. The reappearance of the dehydrogenase activity measures the formation of a dimeric species. The dimerization can occur only after each chain has reached its "native" conformation.(ABSTRACT TRUNCATED AT 250 WORDS)

show abstract

Recent Biochemical and Genetic Studies on the Amino Acid Biosynthetic Pathway of the Aspartate Family in Escherichia coli

Cohen

Veron

Zakin

1985

Modulation by Molecular Interactions - Current Topics in Cellular Regulation

View full text Add to dashboard Cite

Two regions of the bifunctional protein aspartokinase I- homoserine dehydrogenase I are connected by a short hinge.

Cited by 14 publications

References 11 publications

A triglobular model for the polypeptide chain of aspartokinase I-homoserine dehydrogenase I of Escherichia coli

A triglobular model for the polypeptide chain of aspartokinase I-homoserine dehydrogenase I of Escherichia coli

Mechanism of renaturation of a large protein, aspartokinase-homoserine dehydrogenase

Recent Biochemical and Genetic Studies on the Amino Acid Biosynthetic Pathway of the Aspartate Family in Escherichia coli

Contact Info

Product

Resources

About