The Simultaneous Coupling of Transcription and Splicing in Plants

Gene expression involves a three-step process including transcribing precursor messenger RNAs(pre-mRNAs)from DNA templates by RNA polymerase II(Pol II),processing pre-mRNAs into mature mRNAs,and translating mature mRNAs into proteins(Bentley,2014).The maturation of pre-mRNAs entails 5′end capping,pre-mRNA splicing,3′end processing,and RNA modification(Bentley,2014).Pre-mRNA splicing is a two-step transesterification reaction,catalyzed by the spliceosome in recognizing various sequence motifs in pre-mRNAs including 5′and 3′splice sites,branch points,polypyrimidine tracts,and other splicing regulatory elements(Herzel et al.,2017).