2026-09-18T20:41:28Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/22538 2023-07-10 col_2142_5131 col_2142_16338 com_2142_5130 com_2142_16337 com_2142_14793 com_2142_8903

Wolfe, R.S. DiMarco, Anthony Andrew 2011-05-07T13:43:04Z 2011-05-07T13:43:04Z 10000-01-01 1990 The biosynthetic pathway of methanogenesis proceeds via several bound intermediates. One of the coenzymes involved in this conversion is tetrahydromethanopterin (H$\sb4$MPT), a structural and biochemical analog of tetrahydrofolate (THF). Enzymes mediating these reactions in Methanobacterium thermoautotrophicum were subjected to biochemical and molecular analysis to determine their relatedness to the analogous THF-dependent reactions in non-methanogens. Purification of the 5,10-methenyl-H4MPT cyclohydrolase (CYC) revealed that this enzyme was distinct and separable from the enzymes catalyzing the previous formyl group transfer reaction and subsequent reduction reaction. This is an important evolutionary consideration with respect to the THF-utilizing enzymes. Extensive biochemical analysis of the cyclohydrolase was performed to characterize the enzyme's analogy to its THF-utilizing counterpart. This work suggested a functional conservation within the pterin binding sites of different pterin enzymes. To investigate this further, the gene encoding the formyl-MFR:H$\sb4$MPT formyltransferase (FTR) was cloned and sequenced. No similarity with other pterin enzymes was found; FTR apparently possesses a novel pterin binding site. FTR was expressed as a catalytically functional enzyme in E. coli. As the first such success with a methane biosynthetic enzyme, this is an encouraging invitation to further manipulations. Surprisingly, ftr is transcribed as a monocistronic message; promoter and terminator sequences were identified. Biochemical analysis of methyltransfer reactions in this organism, compounded with additional observations relating to other enzymes involved in methanogenesis, led to the proposition of a methanogenic metabolon, the methanogenosome, where methanogenic reactions are physically integrated, but separated from enzyme reactions not involved in methanogenesis. Made available in DSpace on 2011-05-07T13:43:04Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9114222.pdf: 5081351 bytes, checksum: abed9bb72bf6ee80f272e78957b971a8 (MD5) Previous issue date: 1990 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:58:18Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:27:24-05:00 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 U of I Only AAI9114222 (UMI)AAI9114222 http://hdl.handle.net/2142/22538 eng Copyright 1990 DiMarco, Anthony Andrew Biology, Molecular Biology, Microbiology Biochemical and molecular characterization of tetrahydromethanopterin-dependent enzymes in methanogenesis text Ph.D. Microbiology Microbiology University of Illinois at Urbana-Champaign Dissertation