title: Connecting proline and γ-aminobutyric acid in stressed plants through non-enzymatic reactions.
abstract: The accumulation of proline (Pro) in plants exposed to biotic/abiotic stress is a well-documented and conserved response in most vegetal species. Stress conditions induce the overproduction of reactive oxygen species which can lead to cellular damage. In vitro assays have shown that enzyme inactivation by hydroxyl radicals (·OH) can be avoided in presence of Pro, suggesting that this amino acid could act as an ·OH scavenger. We applied Density Functional Theory coupled with a polarizable continuum model to elucidate how Pro reacts with ·OH. In this work we suggest that Pro reacts favourably with ·OH by H-abstraction on the amine group. This reaction produces the spontaneous decarboxylation of Pro leading to the formation of pyrrolidin-1-yl. In turn, pyrrolidin-1-yl can easily be converted to Δ1-pyrroline, the substrate of the enzyme Δ1-pyrroline dehydrogenase, which produces γ-aminobutyric acid (GABA). GABA and Pro are frequently accumulated in stressed plants and several protective roles have been assigned to these molecules. Thereby we present an alternative non-enzymatic way to synthetize GABA under oxidative stress. Finally this work sheds light on a new beneficial role of Pro accumulation in the maintenance of photosynthetic activity.
authors.affiliation: Laboratorio de Bioquímica, Departamento de Biología Vegetal, Facultad de Agronomía, Universidad de la República, Montevideo, Uruguay.
authors.forename: Santiago
authors.initials: S
authors.lastname: Signorelli
authors.affiliation: Joint BSC CRG IRB Research Program in Computational Biology, Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain.
authors.forename: Pablo D
authors.initials: PD
authors.lastname: Dans
authors.affiliation: Laboratorio de Química Teórica y Computacional (LQTC), Instituto de Química Biológica, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay.
authors.forename: E Laura
authors.initials: EL
authors.lastname: Coitiño
authors.affiliation: Laboratorio de Bioquímica, Departamento de Biología Vegetal, Facultad de Agronomía, Universidad de la República, Montevideo, Uruguay.
authors.forename: Omar
authors.initials: O
authors.lastname: Borsani
authors.affiliation: Laboratorio de Bioquímica, Departamento de Biología Vegetal, Facultad de Agronomía, Universidad de la República, Montevideo, Uruguay.
authors.forename: Jorge
authors.initials: J
authors.lastname: Monza
mesh_terms: D000588:Amines / Q000378:metabolism; D017665:Hydroxyl Radical / Q000378:metabolism / Q000494:pharmacology; D008958:Models, Molecular; D008968:Molecular Conformation; D018384:Oxidative Stress / Q000187:drug effects; D010944:Plants / Q000187:drug effects / Q000378:metabolism*; D011392:Proline / Q000737:chemistry / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000588:Amines; D017665:Hydroxyl Radical; D005680:gamma-Aminobutyric Acid; D011392:Proline