The 5′ untranslated region of the soybean cytosolic glutamine synthetase β1 gene contains prokaryotic translation initiation signals and acts as a translational enhancer in plants
- 509 Downloads
Glutamine synthetase (GS) catalyzes the synthesis of glutamine from glutamate and ammonia. In plants, it occurs as two major isoforms, a cytosolic form (GS1) and a nuclear encoded chloroplastic form. The focus of this paper is to determine the role of the 5′UTR of a GS1 gene. GS1 gene constructs with and without its 5′ and 3′ UTRs, driven by a constitutive promoter, were agroinfiltrated into tobacco leaves and the tissues were analyzed for both transgene transcript and protein accumulation. The constructs were also tested in an in vitro transcription/translation system and in Escherichia coli. Our results showed that while the 3′UTR functioned in the destabilization of the transcript, the 5′UTR acted as a translation enhancer in plant cells but not in the in vitro translation system. The 5′UTR of the GS1 gene when placed in front of a reporter gene (uidA), showed a 20-fold increase in the level of GUS expression in agroinfiltrated leaves when compared to the same gene construct without the 5′UTR. The 5′UTR-mediated translational enhancement is probably another step in the regulation of GS in plants. The presence of the GS1 5′UTR in front of the GS1 coding region allowed for its translation in E. coli suggesting the commonality of the translation initiation mechanism for this gene between plants and bacteria.
KeywordsPost-transcriptional regulation Translational control Glutamine synthetase β-Glucuronidase Agroinfiltration
This work was supported by the National Institutes of Health (Grant number S06 GM08136-32), by the US Department of Agriculture (Grant number 2007-03596), and by the Agricultural Experimental Station at New Mexico State University. We thank Dr. Suman Bagga and Dr. Laura Rodriguez-Uribe for their helpful comments on the manuscript.
- Diaz C, Kusano M, Sulpice R, Araki M, Redestig H, Saito K, Stitt M, Shin R (2011) Determining novel functions of Arabidopsis 14-3-3 proteins in central metabolic processes BMC systems. Biol 5:192Google Scholar
- Jiménez-López S, Mancera-Martínez E, Donayre-Torres A, Rangel C, Uribe L, March S, Jiménez-Sánchez G, Sánchez de Jiménez E (2011) Expression profile of maize (Zea mays L.) embryonic axes during germination: translational regulation of ribosomal protein mRNAs. Plant Cell Physiol 52:1719–1733PubMedCrossRefGoogle Scholar
- Markham NR, Zuker M (2008) UNAFold: software for nucleic acid folding and hybridization. In: Keith JM (ed) Bioinformatics, vol II. Structure, function and applications, in methods in molecular biology, vol 453, pp 3–31. Humana Press, Totowa, NJGoogle Scholar
- Roberts CS, Rajagopal S, Smith LA, Nguyen TA, Yang W, Nugroho S, Ravi KS, Cao ML, Vijayachandra K, Patell V, Harcourt RL, Dransfield L, Desamero N, Slamet I, Keese P, Kilian A, Jefferson RA (1998) A comprehensive set of modular vectors for advanced manipulations and efficient transformation of plants by both Agrobacterium and direct DNA uptake methods. pCAMBIA vector release manual version 3.05. CAMBIA. Canberra, AustraliaGoogle Scholar
- Zuker M (1989) On finding all suboptimal foldings of an RNA molecule. Science 244:48–52Google Scholar