FIG. 1.

Isolation, subcloning, and sequencing of the spo4⁺ gene. (A) Isolation of the spo4⁺ gene. Strain MK4L (spo4-B4) was transformed with either pDB248′ or pDB(spo4). The Leu⁺ transformants were incubated on synthetic sporulation medium (SSA) at 28°C for 2 days. (B) Restriction map and construction of null mutants. The open arrows indicate the region and direction of the spo4⁺ open reading frame, which encodes a protein composed of 429 amino acid residues. All subclones were derived from pDB(spo4). Complementation by each subclone is indicated as follows: +, complements; −, does not complement. Restriction enzyme sites: H, HindIII; Hp, HpaI; N, NsiI; S, SalI; Sp, SphI; St, StuI; X, XhoI. (C) Nucleotide and predicted amino acid sequences of spo4⁺. Two introns are marked by underlining. A putative FLEX sequence in the promoter region is boxed.