A spider tRNA(Ala) requires a far upstream sequence element for expression

Within the series of timed differential accumulations of small RNAs we have shown to prelude the synthesis of fibroin in the large ampullate glands of Nephila clavipes (Nc), we are currently directing our attention to the ala nine tRNAs. This work reports the subcloning of the members of a tRNA(Ala) gene cluster and the optimization of their transcription in a heterologous cell-free system derived from Bombyx mori (Bm) silkglands. Our data show th at the heterologous cell-free system supports the faithful and differential transcription of the individual spider alanine tRNA genes. We are thus mak ing use of the extract to characterize the individual genes with respect to flank-contained regulatory elements through cell-free transcription of gen e derivatives. The work has been initiated with pNTA3 because of its high t ranscriptional activity. Interestingly, the transcription of this gene requ ires a far upstream sequence, an uncommon modality in tRNA genes. (C) 1999 Elsevier Science B.V. All rights reserved.