Exploring the evolutionary route of the acquisition of betaine aldehyde dehydrogenase activity by plant ALDH10 enzymes: implications for the synthesis of the osmoprotectant glycine betaine
Por:
Munoz-Clares, RA, Riveros-Rosas, H, Garza-Ramos, G, Gonzalez-Segura, L, Mujica-Jimenez, C, Julian-Sanchez, A
Publicada:
29 may 2014
Categoría:
Plant Science
Resumen:
Background: Plant ALDH10 enzymes are aminoaldehyde dehydrogenases
(AMADHs) that oxidize different.-amino or trimethylammonium aldehydes,
but only some of them have betaine aldehyde dehydrogenase (BADH)
activity and produce the osmoprotectant glycine betaine (GB). The latter
enzymes possess alanine or cysteine at position 441 (numbering of the
spinach enzyme, SoBADH), while those ALDH10s that cannot oxidize betaine
aldehyde (BAL) have isoleucine at this position. Only the plants that
contain A441- or C441-type ALDH10 isoenzymes accumulate GB in response
to osmotic stress. In this work we explored the evolutionary history of
the acquisition of BAL specificity by plant ALDH10s.
Results: We performed extensive phylogenetic analyses and constructed
and characterized, kinetically and structurally, four SoBADH variants
that simulate the parsimonious intermediates in the evolutionary pathway
from I441-type to A441-or C441-type enzymes. All mutants had a correct
folding, average thermal stabilities and similar activity with
aminopropionaldehyde, but whereas A441S and A441T exhibited significant
activity with BAL, A441V and A441F did not. The kinetics of the mutants
were consistent with their predicted structural features obtained by
modeling, and confirmed the importance of position 441 for BAL
specificity. The acquisition of BADH activity could have happened
through any of these intermediates without detriment of the original
function or protein stability. Phylogenetic studies showed that this
event occurred independently several times during angiosperms evolution
when an ALDH10 gene duplicate changed the critical Ile residue for Ala
or Cys in two consecutive single mutations. ALDH10 isoenzymes frequently
group in two clades within a plant family: one includes peroxisomal
I441-type, the other peroxisomal and non-peroxisomal I441-, A441-or
C441-type. Interestingly, high GB-accumulators plants have
non-peroxisomal A441-or C441-type isoenzymes, while low-GB accumulators
have the peroxisomal C441-type, suggesting some limitations in the
peroxisomal GB synthesis.
Conclusion: Our findings shed light on the evolution of the synthesis of
GB in plants, a metabolic trait of most ecological and physiological
relevance for their tolerance to drought, hypersaline soils and cold.
Together, our results are consistent with smooth evolutionary pathways
for the acquisition of the BADH function from ancestral I441-type
AMADHs, thus explaining the relatively high occurrence of this event.
Filiaciones:
Munoz-Clares, RA:
Univ Nacl Autonoma Mexico, Fac Quim, Dept Bioquim, Mexico City 04510, DF, Mexico
Riveros-Rosas, H:
Univ Nacl Autonoma Mexico, Fac Med, Dept Bioquim, Mexico City 04510, DF, Mexico
Garza-Ramos, G:
Univ Nacl Autonoma Mexico, Fac Med, Dept Bioquim, Mexico City 04510, DF, Mexico
Gonzalez-Segura, L:
Univ Nacl Autonoma Mexico, Fac Quim, Dept Bioquim, Mexico City 04510, DF, Mexico
Mujica-Jimenez, C:
Univ Nacl Autonoma Mexico, Fac Quim, Dept Bioquim, Mexico City 04510, DF, Mexico
Julian-Sanchez, A:
Univ Nacl Autonoma Mexico, Fac Med, Dept Bioquim, Mexico City 04510, DF, Mexico
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