Disease relevance of OASA1

• OAS-TL A, B and C were overexpressed in an Escherichia coli mutant lacking cysteine synthesis and exhibited bifunctional OAS-TL and beta-cyanoalanine synthase (CAS) activities [1].

High impact information on OASA1

• Comparison with bacterial OASS suggests that structural plasticity in the active site allows binding of SAT C termini with dissimilar sequences at structurally similar OASS active sites [2].
• In plants, association of O-acetylserine sulfhydrylase (OASS) and Ser acetyltransferase (SAT) into the Cys synthase complex plays a regulatory role in sulfur assimilation and Cys biosynthesis [2].
• In addition, examination of the AtOASS structure and nearly 300 plant and bacterial OASS sequences suggest that the highly conserved beta8A-beta9A surface loop may be important for interaction with serine acetyltransferase, the other enzyme in cysteine biosynthesis [3].
• O-Acetylserine sulfhydrylase (OASS) catalyzes the final step of cysteine biosynthesis, the pyridoxal 5'-phosphate (PLP)-dependent conversion of O-acetylserine into cysteine [3].
• Both effector concentrations are in the range of intracellular O-acetylserine fluctuations and support a functional model that integrates effector-driven cysteine synthase complex dissociation as a regulatory switch for the biosynthetic pathway [4].

Biological context of OASA1

• Expression of wild-type OASA1 or OASA2 transgenes did not affect the Trp content of rice calli or plants [5].
• A DNA regulatory fragment was isolated from the promoter region of the OASA1 gene, encoding the cytosolic O-acetylserine(thiol)lyase enzyme that is highly expressed in Arabidopsis thaliana trichomes [6].
• The cDNA for cysteine synthase encodes an open reading frame of 325 amino acids, of which expression in the E. coli lacking endogenous cysteine synthase genes could functionally rescue the growth without addition of cysteine [7].

Associations of OASA1 with chemical compounds

• Molecular basis of cysteine biosynthesis in plants: structural and functional analysis of O-acetylserine sulfhydrylase from Arabidopsis thaliana [3].
• Although the plant and bacterial OASS share a conserved set of amino acids for PLP binding, the structure of AtOASS reveals a difference from the bacterial enzyme in the positioning of an active site loop formed by residues 74-78 when methionine is bound [3].
• However, transformed calli and plants expressing a mutated OASA1 gene, OASA1(D323N), that encodes a protein in which aspartate-323 is replaced with asparagine manifested up to 180- and 35-fold increases, respectively, in Trp accumulation [5].
• Characterization of rice anthranilate synthase alpha-subunit genes OASA1 and OASA2. Tryptophan accumulation in transgenic rice expressing a feedback-insensitive mutant of OASA1 [5].
• beta-Cyanoalanine synthase is a mitochondrial cysteine synthase-like protein in spinach and Arabidopsis [8].

Analytical, diagnostic and therapeutic context of OASA1

• Molecular cloning and expression analyses of mitochondrial and plastidic isoforms of cysteine synthase (O-acetylserine(thiol)lyase) from Arabidopsis thaliana [9].

References