Fig 2.

4S and 24S mutations are located within the secY promoter. (A) Relative to the predicted translational start site of secY (indicated by start codon GTG), suppressor 4S (NR236) contains a 2-bp insertion between nucleotides −137 and −138. Suppressor 24S (NR151) contains a single nucleotide polymorphism at nucleotide −134. Suppressor mutations are boxed. Potential promoter −10 regions are shown in bold letters. The M. smegmatis −10 region consensus sequence is shown as a sequence logo representing the frequency at which each nucleotide occurs (the percentages are indicated beneath each nucleotide), as reported by Newton-Foot and Gey van Piteus (27). The drawing is not to scale. (B) Transcript 5′ ends identified upstream of secY. By using primer R3, two species of secY transcript 5′ ends were amplified (see the agarose gel inset) from RNA from the complemented secA2 strain (NR172). Relative to the predicted translational start site of secY (GTG), the longer species has a 5′ end at nucleotides −129 to −127, and the shorter species has a 5′ end at nucleotide −75. 5′-end nucleotides are boxed. Potential promoter −10 regions are shown in bold letters. Amplified 5′ end products are represented by wavy lines.