PEDS Advance Access originally published online on January 25, 2006
Protein Engineering Design and Selection 2006 19(4):141-145; doi:10.1093/protein/gzj012
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Construction and optimization of a CC49-Based scFv-ß-lactamase fusion protein for ADEPT
Genencor International, a Danisco company, 925 Page Mill Road, Palo Alto, CA 94304, USA
1 To whom correspondence should be addressed at: Volker Schellenberger, PhD, Vice President of Drug Discovery, microPROTEINS, Inc., 1455 Adams Drive, #1120, Menlo Park, CA 94025, USA; E-mail: vschellenberger{at}mproteins.com
CC49 is a clinically validated antibody with specificity for TAG-72, a carbohydrate epitope that is over-expressed and exposed on a large fraction of solid malignancies. We constructed a single chain fragment (scFv) based on CC49 and fused it to ß-lactamase. The first generation fusion protein, TAB2.4, was expressed at low levels in Escherichia coli and significant degradation was observed during production. We optimized the scFv domain of TAB2.4 by Combinatorial Consensus Mutagenesis (CCM). An improved variant TAB2.5 was identified that resulted in an almost 4-fold improved expression and 2.5° higher thermostability relative to its parent molecule. Soluble TAB2.5 can be manufactured in low-density E.coli cultures at 120 mg/l. Our studies suggest that CCM is a rapid and efficient method to generate antibody fragments with improved stability and expression. The fusion protein TAB2.5 can be used for antibody directed enzyme prodrug therapy (ADEPT).
Keywords: ADEPT/CC49/consensus mutation/scFv/thermostability
Received November 8, 2005; revised December 19, 2005; accepted December 23, 2005.
Edited by Jacques Fastrez