scholarly journals Evidence that glutamic acid 49 of tryptophan synthase alpha subunit is a catalytic residue. Inactive mutant proteins substituted at position 49 bind ligands and transmit ligand-dependent to the beta subunit.

1988 ◽  
Vol 263 (18) ◽  
pp. 8611-8614 ◽  
Author(s):  
E W Miles ◽  
P McPhie ◽  
K Yutani
Keyword(s):  
Glutamic Acid ◽  
Beta Subunit ◽  
Alpha Subunit ◽  
Catalytic Residue ◽  
Tryptophan Synthase ◽  
Mutant Proteins

scholarly journals 5-Fluoroindole resistance identifies tryptophan synthase beta subunit mutants in Arabidopsis thaliana.

Genetics ◽  
1995 ◽  
Vol 140 (1) ◽  
pp. 303-313
Author(s):  
A J Barczak ◽  
J Zhao ◽  
K D Pruitt ◽  
R L Last
Keyword(s):  
Arabidopsis Thaliana ◽  
Protein A ◽  
Beta Subunit ◽  
Alpha Subunit ◽  
Anthranilate Synthase ◽  
Tryptophan Synthase ◽  
Wild Type ◽  
Recessive Mutations ◽  
The Stability

Abstract A study of the biochemical genetics of the Arabidopsis thaliana tryptophan synthase beta subunit was initiated by characterization of mutants resistant to the inhibitor 5-fluoroindole. Thirteen recessive mutations were recovered that are allelic to trp2-1, a mutation in the more highly expressed of duplicate tryptophan synthase beta subunit genes (TSB1). Ten of these mutations (trp2-2 through trp2-11) cause a tryptophan requirement (auxotrophs), whereas three (trp2-100 through trp2-102) remain tryptophan prototrophs. The mutations cause a variety of changes in tryptophan synthase beta expression. For example, two mutations (trp2-5 and trp2-8) cause dramatically reduced accumulation of TSB mRNA and immunologically detectable protein, whereas trp2-10 is associated with increased mRNA and protein. A correlation exists between the quantity of mutant beta and wild-type alpha subunit levels in the trp2 mutant plants, suggesting that the synthesis of these proteins is coordinated or that the quantity or structure of the beta subunit influences the stability of the alpha protein. The level of immunologically detectable anthranilate synthase alpha subunit protein is increased in the trp2 mutants, suggesting the possibility of regulation of anthranilate synthase levels in response to tryptophan limitation.

scholarly journals Tryptophan synthase alpha subunit glutamic acid 49 is essential for activity. Studies with 19 mutants at position 49.

1987 ◽  
Vol 262 (28) ◽  
pp. 13429-13433
Author(s):  
K Yutani ◽  
K Ogasahara ◽  
T Tsujita ◽  
K Kanemoto ◽  
M Matsumoto ◽  
...  
Keyword(s):  
Glutamic Acid ◽  
Alpha Subunit ◽  
Tryptophan Synthase

scholarly journals Substitution of a Surface-Exposed Residue Involved in an Allosteric Network Enhances Tryptophan Synthase Function in Cells

2021 ◽  
Vol 8 ◽  
Author(s):  
Rebecca N. D’Amico ◽  
Yuliana K. Bosken ◽  
Kathleen F. O’Rourke ◽  
Alec M. Murray ◽  
Woudasie Admasu ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Molecular Dynamics ◽  
Active Site ◽  
Beta Subunit ◽  
Alpha Subunit ◽  
Tryptophan Synthase ◽  
Wild Type ◽  
Auxotrophic Strain ◽  
Hydrophobic Tunnel ◽  
Dynamics Simulations

Networks of noncovalent amino acid interactions propagate allosteric signals throughout proteins. Tryptophan synthase (TS) is an allosterically controlled bienzyme in which the indole product of the alpha subunit (αTS) is transferred through a 25 Å hydrophobic tunnel to the active site of the beta subunit (βTS). Previous nuclear magnetic resonance and molecular dynamics simulations identified allosteric networks in αTS important for its function. We show here that substitution of a distant, surface-exposed network residue in αTS enhances tryptophan production, not by activating αTS function, but through dynamically controlling the opening of the indole channel and stimulating βTS activity. While stimulation is modest, the substitution also enhances cell growth in a tryptophan-auxotrophic strain of Escherichia coli compared to complementation with wild-type αTS, emphasizing the biological importance of the network. Surface-exposed networks provide new opportunities in allosteric drug design and protein engineering, and hint at potential information conduits through which the functions of a metabolon or even larger proteome might be coordinated and regulated.

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