NONESSENTIAL FUNCTIONS OF BACTERIOPHAGE LAMBDA

Seven plaque-forming biotin-transducing λ mutants (λbio) have been used to characterize nonessential λ functions. Five of the λbios have deletions in the center of the λ map extending to the right of the attachment region (attλ), as predicted by the Campbell model, but the other two seem to be anomalous in this respect. The extent of the deletions establishes the order attλ-int-(exo,red)-β-cIII, for markers in the λ center. The correlation in position of the exo and red markers suggest that the exonuclease protein is involved in genetic recombination, and the viability of exo-β- λbios shows that neither exonuclease nor β-protein is essential for λ growth. The two anomalous λbios have defects in the b2 region to the left of attλ. The five standard λbios are b2+, yet they appear to have structural integration deficiencies in addition to their functional defects. © 1969.