In vitro interactions between barley TALE homeodomain proteins suggest a role for protein–protein associations in the regulation of Knox gene function
Article first published online: 23 DEC 2001
The Plant Journal
Volume 27, Issue 1, pages 13–23, July 2001
How to Cite
Müller, J., Wang, Y., Franzen, R., Santi, L., Salamini, F. and Rohde, W. (2001), In vitro interactions between barley TALE homeodomain proteins suggest a role for protein–protein associations in the regulation of Knox gene function. The Plant Journal, 27: 13–23. doi: 10.1046/j.1365-313x.2001.01064.x
- Issue published online: 23 DEC 2001
- Article first published online: 23 DEC 2001
- Received 15 January 2001; revised 28 March 2001; accepted 6 April 2001.
- Hooded barley;
- TALE homeodomain proteins;
- protein–protein interactions;
- Knox genes;
- JuBel genes;
- homeobox gene transcription
This paper describes two-hybrid interactions amongst barley homeodomain proteins encoded by the Three Amino acid Loop Extension (TALE) superfamily. The class I KNOX protein BKN3 is shown to homodimerise and to associate with proteins encoded by the class I and II Knox genes BKn-1 and BKn-7. Furthermore, JUBEL1 and JUBEL2, two BELL1 homologous proteins, are identified and characterised as interacting partners of BKN3. Differences in the requirements of BKN3 derivatives for interactions with KNOX and JUBEL proteins imply the involvement of overlapping but slightly different domains. This set of results is an example for interactions amongst different classes of plant TALE homeodomain proteins, as previously described for related animal proteins. Apparently identical spatial and temporal expression patterns of BKn-1, BKn-3, BKn-7, JuBel1 and JuBel2, as determined by in situ hybridisation, are compatible with possible interactions of their protein products in planta. Contradictory to the common model, that the transcriptional down-regulation of certain class 1 Knox-genes is the prerequisite for organ differentiation, transcripts of all five genes were, similar to Tkn1 and Tkn2/LeT6 of tomato, detected in incipient and immature leaves as well as in meristematic tissues. A characteristic phenotype is induced by the overexpression of JuBel2 in transgenic tobacco plants.