MOLECULAR CHARACTERIZATION OF Xenopus HEXOSAMINIDASE: FROM GENE TO STRUCTURAL POLYPEPTIDES

MORALES ES, KRAPF D, BOTTA P, ARRANZ SE.

Casilda

Congreso; XIV Congreso y XXXII Reunión anual de la sociedad de biología de Rosario; 2012

Sociedad de Biología de Rosario

MOLECULAR CHARACTERIZATION OF Xenopus HEXOSAMINIDASE: FROM GENE TO STRUCTURAL POLYPEPTIDES. Enrique S. Morales, Darío Krapf, Pablo Botta y Silvia E. Arranz. Cátedra de Biología. Fac. Cs. Bioq. y Farm.-IBR (UNR-Conicet)- S2002LRK Rosario. E-mail: morales@ibr.gov.ar Hexosaminidase (Hex) is present in vertebrate gametes. It is involved in sperm and egg binding, and polyspermy prevention among phylogenetically distant animals. Mammals Hex is constituted by two subunits (alfa and beta) codified in different genes (HEXA and HEXB). Both subunits have high homology with each other, and differ essentially in the active site. These subunits give rise to three possible Hex isoforms: A(alfa-beta), B(beta-beta), and S(alfa-alfa). In previous studies we have analyzed the activity and immunolocalization of X. laevis egg Hex. However, no information was available regarding the molecular identity of Hex in amphibians. With this aim, we use high homology search and found one putative hex gene in X. tropicalis genome database. However, based in full-ORF transcript databases, two Hex mRNA were found. Noteworthy, one of the transcripts codified an alfa subunit and the other one a beta subunit. Posterior analysis suggested that the transcripts differ in a small fragment of sequence codified in different exons of the gene. This indicates that they could be synthesized as alternative transcripts from the same hex gene founded in X. tropicalis. The same results were found in X. laevis. To analyze this hypothesis we performed a Southern blot assay. The results showed that both transcripts could be synthesized from the same gene. In summary, we present a Xenopus hex gene. Interestingly, alfa and beta Hex subunits are synthesized by alternative transcripts in Xenopus. This finding denotes an evolutionary divergence with mammals where alfa and beta subunits are synthesized from different genes.