IDENTIFICATION, SEQUENCE, PHYLOGENETIC ANALYSIS AND MOLECULAR DYNAMICS SIMULATION OF A NEW SECRETORY PHOSPHOLIPASE A2 FROM GLYCINE MAX SOYBEAN

MARIA E MARIANI; MADOERY RICARDO; FIDELIO, G.D.; MARCOS VILLAREAL

CORDOBA

Jornada; V JORNADAS DE POSGRADO FACULATD DE CIENCIAS QUIMICAS; 2011

Facultad de Ciencias Químicas -UNC

The Phospholipase A2 superfamily is a broad and growing group of enzymes that stereospecifically catalyze the cleavage of the sn-2 acyl ester union of diacyl-phospholipids and liberate 1-acyl-2-lysophospholipids and free fatty acids. Two structural characteristics of any sPLA2 are of high functional interest: the catalytic site and the interfacial recognition surface (IRS). All sPLA2s have the same architecture at the catalytic site level (His-Asp) but differ on the aminoacid residues that compose the IRS. A TBLASTN search of the Glycine max genome mRNA database using Arabidopsis thaliana, Oryza sativa and Zea mays sPLA2s as templates, showed the existence of five putative sPLA2s isoenzymes, denoted as GmsPLA2-I,GmsPLA2-II, GmsPLA2-III, GmsPLA2-IV and GmsPLA2-V. The five sPLA2s sequences contained a conserved PA2c domain having the Ca2+- binding loop (YGKYCGxxxxGC) and the active site motif (DACCxxHDxC) and the His/Asn, His or Ser dyad. A phylogenetic tree of Glycine max sPLA2s was proposed after sequence alignment. The sequences were grouped in two categories (known as group XIA and XIB) on the basis of their differences in molecular weight and deviating sequences especially in the N- and C- terminal regions of the proteins. Enzymes of these groups differ in the third Ca2+ coordinating amino acid and the amino acid composition of the ?dyad?. Homology Modeling and Molecular Dynamics generated on the basis of the known crystal structure of Rice isoform II, allowed first insights into the three-dimensional structure of the protein GmsPLA2-I in solution and at the membrane.