Journal: Nucleic Acids Research

Article Title: NAD + capping of sibD transcripts in E. coli is mediated by its minimal promoter and enhanced by ppGpp

doi: 10.1093/nar/gkag102

Figure Lengend Snippet: Several RNAs transcribed by the sibD minimal promoter from E. coli chromosomal DNA could be NAD capped. ( A ) Schematic illustration of gene editing designs in the E. coli genome for four small RNAs expression driven by the sibD minimal promoter. The gene body of trpT is highlighted in purple, sroC in green, and ryjA and symR in blue. The sibD minimal promoter ( sibD P-35 ) is labelled as a short red line, and the rrnB terminator is highlighted in yellow. ( B ) Detection of NAD caps in SibD, TrpT, RyjA, SroC, and SymR RNAs with NADbio-northern blotting in the wild-type and indicated mutant strains. ‘ADPRC+’ indicates the biotinylation of NAD-RNAs via the ADPRC-SPAAC reaction with sufficient ADPRC, while ‘ADPRC−’ denotes the ADPRC-SPAAC reaction without ADPRC. 5S RNAs were detected as loading controls. ( C ) Detection and quantification of NAD-RNAs from SibD, TrpT, RyjA, SroC, and SymR using APB gel blotting. Capping ratios were calculated based on the band intensity of the capped transcripts relative to the total transcripts (both capped and uncapped transcripts) in the APB gel.

Article Snippet: To perform IVT assays with various sigma factors, a similar assay was conducted, except the E. coli RNAP holoenzyme was replaced by the same amount of E. coli RNAP core enzyme (NEB) and in the absence of ppGpp or DksA.

Techniques: Expressing, Northern Blot, Mutagenesis

Journal: Nucleic Acids Research

Article Title: NAD + capping of sibD transcripts in E. coli is mediated by its minimal promoter and enhanced by ppGpp

doi: 10.1093/nar/gkag102

Figure Lengend Snippet: Effects of (p)ppGpp and DksA on transcription and NAD capping of certain small RNAs in E. coli cells. ( A ) The NAD capping level of SibD increased upon transient induction of RelA 455aa and DksA. Both RelA 455aa and DksA were expressed from plasmids under the control of the pBAD promoter. NAD capping of SibD was assessed by APB gel blotting. The total level of SibD RNA in each lane was quantified from the normal gel using ImageJ software and normalized to the intensity in the first EV lane. The NAD capping ratio was calculated as the percentage of the intensity of the NAD-capped band relative to the sum of the intensities of both the capped and uncapped bands in the APB gel. ‘Arabinose−’ indicates RNA samples without arabinose induction, while ‘Arabinose+’ signifies that arabinose was added to induce the expression of RelA 455aa and DksA. ‘EV’ indicates strain carrying the empty pBAD33.1 vector. The tmRNA was used as a loading control and each blotting has three independent replicates. ( B ) Detection of NAD-capped transcripts of five sRNAs with NADbio-northern blotting analysis, including four known NAD-RNAs: SibC, SibD, SibE, and GcvB. The tmRNA was used as a loading control. ( C – G ) Detection of total transcripts and NAD-capped transcripts of five sRNAs, namely SibA, SibC, SibD, SibE, and GcvB, respectively. The total abundance of individual RNA was determined by electrophoresis on a standard PAGE gel followed by northern blotting (labelled as normal gel), while the NAD-capped transcripts were identified with APB gel blotting (labelled as APB gel). The non-NAD-RNA SibA was included as a negative control. The NAD capping ratio was calculated based on the band intensity of the NAD-capped version relative to the total transcription levels (NAD-capped version plus uncapped version). Two types of synthetic RNAs for each sRNA, namely with 5′-ppp- and 5′-NAD modifications, were used as controls.

Article Snippet: To perform IVT assays with various sigma factors, a similar assay was conducted, except the E. coli RNAP holoenzyme was replaced by the same amount of E. coli RNAP core enzyme (NEB) and in the absence of ppGpp or DksA.

Techniques: Control, Software, Expressing, Plasmid Preparation, Northern Blot, Electrophoresis, Negative Control