Abstract: Disclosed is a method for identifying and isolating gene sequences coding for polypeptide sequences which result in specific functional activities or phenotypes, which may then be synthesized and assembled to form new proteins. The assembled protein may contain only amino acid sequences essential for specific functions, have a new quaternary structure resulting from addition of an amino acid sequence with oligomeric activity, or exhibit multiple activities. Also disclosed is a method for identifying, analyzing and synthesizing amino acid sequences with oligomeric activity which may be used to enhance or add a new activity to a protein.In one embodiment, the piece with oligomeric activity is fused onto a polypeptide with one or more additional activities. In another embodiment, this polypeptide sequence is hybridized with a second polypeptide consisting only of the sequence with oligomeric activity.

Abstract: Disclosed is a method for the deletion of a gene from a bacteria using a single step procedure that is applicable to any essential or nonessential gene which has been cloned. The process requires the construction of chromosomal deletions by transformation of a cell strain with linear DNA fragments containing a locus for resistance to an antibiotic, or any other gene allowing for rapid phenotypic selection, flanked by sequences homologous to a closely spaced region on the cell chromosome. By selecting for a double-crossover event between the homologous sequences, shown by the antibiotic resistant or other detectable phenotype, a chromosome disruption can be selected for which has effectively deleted an entire gene.If the gene is essential to viability, the bacteria may be transformed with a plasmid which has a temperature-sensitive replicon and a wild-type allele of the essential gene. When E.