Isolation of plant transcription factors using a modified yeast one-hybrid system

Background: The preparation of expressional cDNA libraries for use in the yeast two-hybrid system is quick and efficient when using the dedicated Clontech (TM) product, the MATCHMAKER Library Construction and Screening Kit 3. This kit employs SMART technology for the amplification of full-length cDNAs, in combination with cloning using homologous recombination. Unfortunately, such cDNA libraries prepared directly in yeast can not be used for the efficient recovery of purified plasmids and thus are incompatible with existing yeast one-hybrid systems, which use yeast transformation for the library screen. Results: Here we propose an adaptation of the yeast one-hybrid system for identification and cloning of transcription factors using a MATCHMAKER cDNA library. The procedure is demonstrated using a cDNA library prepared from the liquid part of the multinucleate coenocyte of wheat endosperm. The method is a modification of a standard one-hybrid screening protocol, utilising a mating step to introduce the library construct and reporter construct into the same cell. Several novel full length transcription factors from the homeodomain, AP2 domain and E2F families of transcription factors were identified and isolated. Conclusion: In this paper we propose a method to extend the compatibility of MATCHMAKER cDNA libraries from yeast two-hybrid screens to one-hybrid screens. The utility of the new yeast one-hybrid technology is demonstrated by the successful cloning from wheat of full-length cDNAs encoding several transcription factors from three different families.