Identifying Substrate Specificity of Adenylation Domains in Methanogen NRPS Enzymes

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dc.contributor.advisor Lee, V en Matthews, Micheal en 2018-02-11T22:29:57Z en 2017 en
dc.identifier.uri en
dc.description Full text is available to authenticated members of The University of Auckland only. en
dc.description.abstract Inhibition of methane-producing archaea in ruminant animals has been an active area of research for many years, primarily motivated by pressures to minimise the carbon footprint of ruminant-based agriculture. To date, approaches to reduce methane production in ruminants have been only partially successful. Nonribosomal peptide synthetase (NRPS) enzymes (mru_0068, mru_0351, sm9_0755, and sm9_0760) from Methanobrevibacter ruminantium M1 and Methanobrevibacter millerae SM9 have been identified as potential molecular targets with which to develop methanogen reduction strategies. In bacteria and fungi, NRPS enzymes are involved in the synthesis of important secondary metabolites and as such are expected to confer significant survival advantage to producing methanogens. Crucial to understanding the biological role of these NRPS enzymes in their native hosts is the ability to synthesise their products in vitro, which in turn requires an understanding of substrate selection by the NRPS adenylation (A) domains. In this research project, attempts were made to determine the substrate selectivity of three different A domains in the NRPS enzymes. Internal A domain constructs for mru_0068-A1, mru_0068-A2, and mru_0351-A3 from M. ruminantium M1 were subcloned from the full-length NRPS enzymes with the aim of creating constructs amenable to purification into monomeric, soluble form. Attempts were made to purify the domains mru_0068-A2 and mru_0351-A3, however significant aggregation was observed for mru_0068-A2, reflecting ongoing challenges within the field for the expression of internal A domain truncations. Successful purification of soluble, monomeric mru_0351-A3 protein supported functional and structural studies into its substrate selectivity. Results from a biochemical PPi-release assay revealed that the A domain preferentially selects amino acid substrates on the basis of hydrophobic sidechain moieties, specifically valine, leucine, norvaline, and 2-aminobutyric acid. Attempts to crystallise the protein and determine its structure were not successful. Nevertheless, isolation of mru_0351-A3 in soluble, monomeric form has provided an experimental pathway by which to continue characterising its specificity through structural approaches and enzyme kinetics studies. Conditions for soluble expression of the mru_0068-A1 domain were also identified. en
dc.publisher ResearchSpace@Auckland en
dc.relation.ispartof Masters Thesis - University of Auckland en
dc.relation.isreferencedby UoA99265058009402091 en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
dc.rights Restricted Item. Available to authenticated members of The University of Auckland. en
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dc.title Identifying Substrate Specificity of Adenylation Domains in Methanogen NRPS Enzymes en
dc.type Thesis en Biological Sciences en The University of Auckland en Masters en
dc.rights.holder Copyright: The author en
pubs.elements-id 724107 en
pubs.record-created-at-source-date 2018-02-12 en

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