Selective in vitro transcription of chloroplast genes

J Cell Biochem. 1983;22(1):31-46. doi: 10.1002/jcb.240220104.


Transcription of Euglena gracilis chloroplast genes has been investigated by using in vitro transcription systems. A DNA-dependent RNA polymerase responsible for the transcription of rRNA genes has been isolated as a nucleoprotein complex (transcriptionally active chromosome). The RNA polymerase remains tightly bound to the chloroplast DNA template and does not initiate transcription with cloned chloroplast genes. A transcriptionally active extract has been prepared from intact Euglena chloroplasts. The soluble RNA polymerase in this extract recognizes cloned chloroplast tRNA genes and tRNA-sized products have been detected after transcription. The tRNA-sized molecules specifically hybridize to the tRNA genes in the plasmid DNA. At least five tRNA-sized products have been identified from transcription of a trnY1trnH1-trnM1-trnE1-trnW1-trnG1 cluster. Evidence is also presented that processing enzymes in the chloroplast-extract can recognize a polycistronic tRNAVal-tRNAAsn-tRNAArg precursor and process it into tRNA-sized molecules. Truncated templates have been used to demonstrate that the chloroplast tRNA genes are actively transcribed. From a comparison of 5' flanking sequences in chloroplast tRNA genes, a consensus sequence which might function as a promoter, has been identified. The properties of the RNA polymerase involved in the transcription of chloroplast rRNA genes and tRNA genes have been investigated and compared.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Chloroplasts / enzymology
  • Chloroplasts / metabolism*
  • DNA-Directed RNA Polymerases / metabolism
  • Euglena gracilis / enzymology
  • Euglena gracilis / genetics
  • Genes*
  • RNA, Transfer / metabolism
  • Transcription, Genetic*


  • RNA, Transfer
  • DNA-Directed RNA Polymerases