FIG. 2.

Diagram of construction of chromosomal mutants. Genes deleted or mutated are indicated. Only relevant restriction sites are included: A, SalI; C, ClaI; D, NdeI; E, EcoRV; H, HpaI; K, KpnI; M, MunI; N, NruI; P, PstI; and S, SnaBI. Plasmids are described in Table 2. Crossed lines denote recombination.