Gisele Monteiro
University of São Paulo, Brazil
Title: Protein engineering applied to obtain biobetters of antitumor enzyme asparaginase
Biography
Biography: Gisele Monteiro
Abstract
Asparaginase (ASNase), an enzyme biotechnologically produced by bacteria, is one of the most important compounds in polychemotherapy to treat acute lymphoblastic leukemia (ALL) in children. There are only three options available as medicine: native enzyme from Erwinia chrysanthemi (ErA) or extracted from Escherichia coli (EcA) and formulated as native or PEGylated (PEG-EcA). However, these options yet present some problems in patients, such as to elicit hypersensitivity and allergenic reactions, neurotoxicity, and hyperammonemia. Aiming to avoid some of these problems, our research group has developed several different mutant proteoforms, expressed in bacteria and yeast, in periplasmic or secreted to extracellular space; with improvement in specific activity, kinetic parameters and stability; different oligomerization states, glycosylated or not, through engineering of genes from E. coli, E. chrysanthemi and S. cerevisiae. We obtained mutants from E. coli ASNase more resistant to human proteases and less immunogenic. In relation to E. chrysanthemi enzyme, our mutants present higher asparaginase activity than the native form, with improved kcat. In addition, we obtained strains of Pichia pastoris that express glycosylated ASNases from bacteria. Last but noteworthy, we obtained P. pastoris and E. coli strains that express active ASNases from S. cerevisiae, an eukaryotic promising options to replace bacterial formulations.