One of the major challenges for maize improvement is to enhance the protein quality of the endosperm. We do not know what genes encode the proteins that contribute most to the protein quality, but lysine is the most limiting amino acid. One way to determine the proteins made in the endosperm is by isolating the genes expressed in this tissue and identifying their function. The results of the maize genome project with etiolated seedling and endosperm cDNA libraries support the basis of this strategy, in that the putative functions of a large number of cDNA sequences were identified through sequence similarity comparison and genomic Southern analyses. One of the genes I selected for further analyses is the elongation factor 1 alpha (eEF1A) gene family. eEF1A interacts with many cellular components and is therefore classified as a multifunction protein. In addition, its level is highly correlated with the amount of protein-bound lysine in maize endosperm. Even though many proteins are known to interact with eEF1A, the basis for the relationship between eEF1A and endosperm lysine content is not known. Transcript level and sequence of different members of the maize eEF1A gene family were analyzed in this work. All the eEF1A maize genes examined had GTP, aminoacyl tRNA, eEF1B and actin binding domains. The substitution of glutamic acid for aspartic acid in a region that has been shown to be important for actin binding in eEF1Aa, eEF1Ae and eEF1Af suggest that there might be two groups of eEF1A genes that bind differently to actin. Analysis of transcript levels demonstrated that different members of the eEF1A gene family are expressed at different levels in the tissues examined. The results from the analyses of transcript levels demonstrated that most of the maize eEF1A gene family members are expressed and their mRNAs vary in different tissues and in developing endosperm. Physiological differences were also determined for the two most abundant eEF1As members by the yeast two-hybrid system. This research provides a significant step toward understanding eEF1A functions in maize and why this protein correlates with the lysine content of the endosperm.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/282611 |
| Date | January 1998 |
| Creators | Carneiro, Newton Portilho, 1963- |
| Contributors | Larkins, Brian A. |
| Publisher | The University of Arizona. |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | text, Dissertation-Reproduction (electronic) |
| Rights | Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. |
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