SsrA-mediated trans-translation plays a role in mRNA quality control by facilitating degradation of truncated mRNAs

Northern blot analysis of mRNAs derived from the wild-type and terminatorless crp genes. The crp mRNAs were expressed in three different cells, TA331 (ssrA⁻), W3110 (ssrA⁺), and TA371 (ssrA^DD), harboring pHA7 derivatives. Total RNAs (5 μg) were subjected to Northern blot analysis using a DIG-labeled 5′ probe A (A) and 3′ probe B (B). Asterisks indicate the major crp mRNA band whose 3′ ends are mapped just after the stem and loop structure of the crp terminator. The vertical bar and the dashed vertical bar represent truncated crp mRNAs and longer dispersed crp mRNAs, respectively. The positions of RNA size markers are shown on the right.