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Title: | Analysis of C4-Dicarboxylic Acid Transport Genes in Rhizobium Meliloti |
Other Titles: | C4-Dicarboxylic Acid Transport Genes in R. Meliloti |
Authors: | Yarosh, Oksana |
Advisor: | Finan, T. M. |
Department: | Biology |
Keywords: | c4;dicarboxylic acid;transport gene;gene;rhizobium meliloti |
Publication Date: | Jan-1989 |
Abstract: | Rhizobium meliloti mutants defective in C₄-dicarboxylic acid transport (Dct⁻) were previously isolated by Tn5 mutagenesis, and divided into two groups based on complementation of Dct- with cosmid clones. In this work further characterization was carried out on the two loci. Group I mutants were found to be defective in dicarboxylate transport (Dct⁻), nitrate utilization, and symbiotic nitrogen fixation. Subcloning and complementation work confined the Group I mutations to a 3.5 kbp BamHI-EcoRI fragment containing the ntrA gene. Group V mutants were defective in dicarboxylate transport and demonstrated varying levels of nitrogen fixation. Complementation and site-directed Tn5 mutagenesis revealed three transcriptional units, corresponding to dctA, dctB, and dctD, localized within a 6 kbp HindIII fragment. The use of dctA::TnphoA fusions determined the expression of dctA to be ntrA, dctB, and dctD dependent. Dct+ revertants of dctB and dctD mutants were selected which carried second-site mutations responsible for restoring the Dct⁺ phenotype. |
URI: | http://hdl.handle.net/11375/22936 |
Appears in Collections: | Digitized Open Access Dissertations and Theses |
Files in This Item:
File | Description | Size | Format | |
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yarosh_oksana_k_1989Jan_masters.pdf | 4.65 MB | Adobe PDF | View/Open |
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