"Novel active site structure conformation of AYWB Phytoplasma malic enzyme"

ALVAREZ C.E.; TRAJTENBERG F.; LARRIEUX N.; SAIGO M.; MUSSI M.A.; ANDREO C. S.; DRINCOVICH M. F.; BUSCHIAZZO A.

Mar del Plata

Congreso; VL CONGRESO DE LA SOCIEDAD ARGENTINA DE BIOQUÍMICA Y BIOLOGÍA MOLECULAR (SAIB); 2015

SAIB

Phytoplasmas are wall-less phytopathogenic bacteria that produce devastating effects on a wide variety of plants. Phytoplasmas genomes have lost many metabolic genes as a result of reductive evolution, it seems that malate is probably a major energy source for phytoplasmas as these bacteria are limited in the processing of carbohydrates. Considering this, we have performed a detailed characterization of the Candidatus Phytoplasma AYWB malic enzyme (AYWB-ME). All the results obtained indicate that this enzyme is involved in energy generation. The differential properties of this enzyme, in combination with the fact that AYWB-ME is one of the smallest among all MEs characterized, made us wonder how this small protein has retained the enzymatic activity and gained its particular modulation. To answer this issue, we have recently obtained the first structure of a AYWB-ME at 2.6 Å resolution. The structure shows a dimer conformation based on a scaffold with unique characteristics. Among these, it is observed that the active site of each monomer is complemented by essential residues (e.g. Tyr 36) from the other monomer. Besides, a complete comparison with the human ME showed different catalytic and structural residues. AYWB-ME structure have a novel strategy for a ME to build its active site, making this enzyme an interesting starting point to make a rational genetic design of ME.