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oai:www.ideals.illinois.edu:2142/23654 2023-07-10 col_2142_5131 col_2142_16338 com_2142_5130 com_2142_16337 com_2142_14793 com_2142_8903

U of I Only AAI9503165 (UMI)AAI9503165 http://hdl.handle.net/2142/23654 eng Copyright 1994 Cho, Hyeseon Biology, Molecular Cronan, John E. Cho, Hyeseon 2011-05-07T14:22:06Z 2011-05-07T14:22:06Z 10000-01-01 1994 "In order to elucidate the in vivo role(s) of Escherichia coli thioesterases which currently lack an assigned function in lipid metabolism, I have cloned the structural gene for Escherichia coli thioesterase I (called tesA) by use of sequence data obtained from the purified protein. I have constructed and characterized a strain carrying a null mutation of the tesA gene and a strain carrying a plasmid that gave massive overproduction of TesA. In addition, I have studied a strain containing double null mutations in both tesA and tesB (the structural gene for E. coli thioesterase II). DNA and protein sequence data predict that thioesterase I (long believed to be a cytoplasmic protein) is exported to the cell periplasm and this prediction is supported by release of the enzyme from cells upon osmotic shock. To gain insight into the catalytic mechanism of the enzyme, I have identified the ""active site serine"" of thioesterase I by radiochemical modification." The possibility of coupling between fatty acid synthesis and phospholipid synthesis has been one of the unanswered questions in E. coli lipid biosynthesis. Using a plasmid encoding a TesA protein lacking its leader peptide (generated by site-directed mutagenesis), I have shown evidence that fatty acid synthesis and phospholipid synthesis are coupled in E. coli and that the coupling is probably maintained via a negative feedback inhibition mechanism using an effector molecule(s) such as fatty acyl-ACP(s). Finally, I have shown that the TesA protein functions not as a protease as reported by other groups but as a thioesterase in vivo. I have also discussed the significance of two open reading frames (ORFs) which overlap with the tesA gene and the possible involvement of the tesA gene and these two ORFs in uptake and/or catabolic processes of a substrate(s). Made available in DSpace on 2011-05-07T14:22:06Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9503165.pdf: 4121837 bytes, checksum: ee69e7807c33729cca7a6583a864efe0 (MD5) Previous issue date: 1994 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T15:05:56Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:31:38-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission ETDs are only available to UIUC Users without author permission Biology, Genetics Biology, Microbiology Molecular and biochemical studies of Escherichia coli thioesterase I text Biology, Molecular Biology, Genetics Biology, Microbiology Biology, Molecular Biology, Genetics Biology, Microbiology University of Illinois at Urbana-Champaign Dissertation Ph.D.