FIGURE 3.

Lack of poly(A) polymerase I results in increasing levels of MicA*. (A) Impact of poly(A) polymerase I (pcnB) in the degradation of the small MicA RNA in Hfq⁺ or Hfq⁻ cells. Stationary-phase cultures of wild type and its derivatives pnp, ΔpcnB, hfq pnp, hfq, and hfq ΔpcnB strains were treated with rifampicin, and total RNA was analyzed by Northern blot. MicA was detected by use of a specific riboprobe. Only the shorter MicA* RNA is visible in the Hfq⁻ cells. A nonspecific band cross-reacting with MicA probe was used as loading control. (B) The steady-state levels of several small RNAs from stationary-phase cultures of hfq and hfq ΔpcnB mutants were evaluated by Northern blot.