Expression of simian virus 40 large T antigen in Escherichia coli using vectors based on the regulatable rac promoter

Simian Virus 40 large T antigen is a multi-functional protein that is involved in the initiation of viral DNA replication, regulation of viral transcription and cell transformation. Bacterial expression vectors, pER23-1 and pER23-2, that are based on the regulatable rac promoter were used to produce T antigen either as a free protein or as a fusion protein. We have observed efficient transcription of the cloned T antigen gene in most of the recombinants. However, expression of the T antigen protein was inefficient and most of the expressed protein was truncated. This may be due to differences in codon usage in E. coli or to rapid protein degradation.