{"id":1248,"date":"2019-07-23T19:39:02","date_gmt":"2019-07-23T11:39:02","guid":{"rendered":"http:\/\/www.bioactivescreeninglibrary.com\/?p=1248"},"modified":"2022-01-07T10:54:01","modified_gmt":"2022-01-07T02:54:01","slug":"moieties-protrude-nam-binding-site-mimic-natural-substrate-form-covalent-adducts-prpp","status":"publish","type":"post","link":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/2019\/07\/23\/moieties-protrude-nam-binding-site-mimic-natural-substrate-form-covalent-adducts-prpp\/","title":{"rendered":"Moieties protrude into the NAM binding site and mimic the natural substrate to form covalent adducts with PRPP"},"content":{"rendered":"

NAMPT mutations that confer resistance to GMX1778, APO866 or TP201565, a structural analog of GMX1778 have been mapped to G217R, H191R, D93del, and Q388R. Based on the wild-type LY294002<\/a> enzyme structure, residues G217R and H191R appeared to protrude into the inhibitor-binding pocket, while D93 and Q388 are located on the dimer interface. In this work, we identify and characterize six mutations in NAMPT that confer resistance to a novel small molecule inhibitor of NAMPT, GNE-618. These include G217R, D93del as well as 4 previously unreported mutations. Furthermore, we determine the crystal structures of six NAMPT mutants in the apo form and in complex with various inhibitors and present a definitive model to explain the differential effects of the mutations on various structural classes of NAMPT inhibitors. We identified and characterized a variety of NAMPT protein mutations mediating resistance against the bi-aryl sulfone inhibitors, exemplified by GNE-618. The identification of resistance mutations in S165 is unexpected given its distance from the inhibitor-binding site. However, expression of S165F or S165Y mutant NAMPT proteins in a naive cell line resulted in decreased sensitivity to GNE-618, indicating that these mutations are sufficient to cause resistance to this NAMPT inhibitor. Furthermore, xenografts derived from cells harboring the S165Y mutation in NAMPT are resistant to GNE-618 at doses that are efficacious in the parental line, suggesting that this is relevant in vivo. Structural analyses of S165 NAMPT mutant proteins establish the critical role of the 380GRS in NAMPT catalysis. Crystal structures revealed a previously underappreciated conformational flexibility in this secondary structure element that can be exploited by resistance mutations through an allosteric mechanism. Our finding regarding the S165F\/Y mechanism of action provides an explanation regarding another mutant, Q388R, previously reported to cause resistance to GMX1778. Q388 is located at the C-terminal end of the 380GRS, and is normally buried under the protein surface. It is unlikely for an arginine residue to settle in the same space and maintain the wild-type ALK5 Inhibitor II<\/a> conformation of the helix. Given the flexibility associated with the 380GRS revealed by our analysis, we propose that R388 is likely to drive it into an alternative conformation that can negatively impact NAMPT inhibitor potency. In conclusion, we present a systematic approach of identifying resistant mutations and elucidating their mechanism of action. Our work provides the most comprehensive to-date structural analysis of resistance mutations to NAMPT inhibitors, important for future rational drug design of more effective inhibitors against this target and similar classes of enzymes and for better understanding of the catalytic mechanism for this important metabolic enzyme. Virus infection triggers the cellular interferonresponse to produce Type 1 IFN’s alpha and beta. Secreted IFNa\/b can stimulate the JAK-STAT pathway in an autocrine or paracrine manner to activate hundreds of IFN-stimulated genes, many of which have antiviral activities that elicit an antiviral state. Although the IFN system constitutes a powerful antiviral response, it rarely works to full capacity because virusencoded IFN antagonists circumvent it. Manipulation of a virus’s capacity to circumvent the IFN response enables both basic research and various practical applications. For example, genetic engineering has facilitated rational design of live-attenuated vaccines, where a common approach is to disable a virus’s IFN antagonist thereby restricting its ability to circumvent the IFN response.<\/p>\n","protected":false},"excerpt":{"rendered":"

NAMPT mutations that confer resistance to GMX1778, APO866 or TP201565, a structural analog of GMX1778 have been mapped to G217R, H191R, D93del, and Q388R. Based on the wild-type LY294002 enzyme structure, residues G217R and H191R appeared to protrude into the inhibitor-binding pocket, while D93 and Q388 are located on the dimer interface. In this work, … Continue reading “Moieties protrude into the NAM binding site and mimic the natural substrate to form covalent adducts with PRPP”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[],"_links":{"self":[{"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/posts\/1248"}],"collection":[{"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/comments?post=1248"}],"version-history":[{"count":1,"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/posts\/1248\/revisions"}],"predecessor-version":[{"id":1249,"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/posts\/1248\/revisions\/1249"}],"wp:attachment":[{"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/media?parent=1248"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/categories?post=1248"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/tags?post=1248"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}