Figure 11.

Suppressors of lapC190 that restore growth at high temperature mapping either to the promoter region of the lapA/B operon or in the lapA gene reduce the LapB abundance. (A) Isogenic cultures of wild type, its lapC190 derivative and lapC190 with a specific suppressor mutation in the lapA gene or its promoter region were adjusted to an OD₅₉₅ of 0.1, serially diluted, 5 μL aliquots spotted on either LA agar or MacConkey agar at various indicated temperatures and plates incubated for 24 h. (B) Immunoblots of whole cell lysates obtained from isogenic strains with indicated genotypes using LapB-specific antibodies. An equivalent amount of total proteins was loaded. As controls, extracts from ΔlapA/B and purified LapB (lanes 1&10) were applied. (C) The position of various suppressor mutations in the lapA gene is indicated. The presence of IS element in either the coding region or the promoter region is indicated by a triangle at the specific nt position. Other mutations causing frame shifts or introducing stop codons, resulting into either truncation of LapA or alterations in the amino acid sequence, are indicated and underlined with the indicated stop codon as * symbol.