{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,7,30]],"date-time":"2025-07-30T13:19:28Z","timestamp":1753881568253,"version":"3.41.2"},"reference-count":30,"publisher":"American Society for Microbiology","issue":"2","license":[{"start":{"date-parts":[[2024,2,28]],"date-time":"2024-02-28T00:00:00Z","timestamp":1709078400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2024,2,28]],"date-time":"2024-02-28T00:00:00Z","timestamp":1709078400000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.asm.org\/non-commercial-tdm-license"}],"content-domain":{"domain":["journals.asm.org"],"crossmark-restriction":true},"short-container-title":["mSphere"],"published-print":{"date-parts":[[2024,2,28]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n          <jats:sec>\n            <jats:title\/>\n            <jats:p>\n              Rickettsiae are Gram-negative obligate intracellular parasites of numerous eukaryotes. Human pathogens of the transitional group (TRG), typhus group (TG), and spotted fever group (SFG) rickettsiae infect blood-feeding arthropods, have dissimilar clinical manifestations, and possess unique genomic and morphological attributes. Lacking glycolysis, rickettsiae pilfer numerous metabolites from the host cytosol to synthesize peptidoglycan and lipopolysaccharide (LPS). For LPS, O-antigen immunogenicity varies between SFG and TG pathogens; however, lipid A proinflammatory potential is unknown. We previously demonstrated that\n              <jats:italic>Rickettsia akari<\/jats:italic>\n              (TRG),\n              <jats:italic>Rickettsia typhi<\/jats:italic>\n              (TG), and\n              <jats:italic>Rickettsia montanensis<\/jats:italic>\n              (SFG) produce lipid A with long 2\u2032 secondary acyl chains (C16 or C18) compared to short 2\u2032 secondary acyl chains (C12) in\n              <jats:italic>Rickettsia rickettsii<\/jats:italic>\n              (SFG) lipid A. To further probe this structural heterogeneity and estimate a time point when shorter 2\u2032 secondary acyl chains originated, we generated lipid A structures for two additional SFG rickettsiae (\n              <jats:italic>Rickettsia rhipicephali<\/jats:italic>\n              and\n              <jats:italic>Rickettsia parkeri<\/jats:italic>\n              ) utilizing fast lipid analysis technique adopted for use with tandem mass spectrometry (FLAT\n              <jats:sup>n<\/jats:sup>\n              ). FLAT\n              <jats:sup>n<\/jats:sup>\n              allowed analysis of lipid A structure directly from host cell-purified bacteria, providing a substantial improvement over lipid A chemical extraction. FLAT\n              <jats:sup>n<\/jats:sup>\n              -derived structures indicate SFG rickettsiae diverging after\n              <jats:italic>R. rhipicephali<\/jats:italic>\n              evolved shorter 2\u2032 secondary acyl chains. While 2\u2032 secondary acyl chain lengths do not distinguish\n              <jats:italic>Rickettsia<\/jats:italic>\n              pathogens from non-pathogens,\n              <jats:italic>in silico<\/jats:italic>\n              analyses of\n              <jats:italic>Rickettsia<\/jats:italic>\n              LpxL late acyltransferases revealed discrete active sites and hydrocarbon rulers for long versus short 2\u2032 secondary acyl chain addition. Our collective data warrant determining\n              <jats:italic>Rickettsia<\/jats:italic>\n              lipid A inflammatory potential and how structural heterogeneity impacts lipid A-host receptor interactions.\n            <\/jats:p>\n            <jats:sec>\n              <jats:title>IMPORTANCE<\/jats:title>\n              <jats:p>\n                Deforestation, urbanization, and homelessness lead to spikes in Rickettsioses. Vector-borne human pathogens of transitional group (TRG), typhus group (TG), and spotted fever group (SFG) rickettsiae differ by clinical manifestations, immunopathology, genome composition, and morphology. We previously showed that lipid A (or endotoxin), the membrane anchor of Gram-negative bacterial lipopolysaccharide (LPS), structurally differs in\n                <jats:italic>Rickettsia rickettsii<\/jats:italic>\n                (later-evolving SFG) relative to\n                <jats:italic>Rickettsia montanensis<\/jats:italic>\n                (basal SFG),\n                <jats:italic>Rickettsia typhi<\/jats:italic>\n                (TG), and\n                <jats:italic>Rickettsia akari<\/jats:italic>\n                (TRG). As lipid A structure influences recognition potential in vertebrate LPS sensors, further assessment of\n                <jats:italic>Rickettsia<\/jats:italic>\n                lipid A structural heterogeneity is needed. Here, we sidestepped the difficulty of\n                <jats:italic>ex vivo<\/jats:italic>\n                lipid A chemical extraction by utilizing fast lipid analysis technique adopted for use with tandem mass spectrometry, a new procedure for generating lipid A structures directly from host cell-purified bacteria. These data confirm that later-evolving SFG pathogens synthesize structurally distinct lipid A. Our findings impact interpreting immune responses to different\n                <jats:italic>Rickettsia<\/jats:italic>\n                pathogens and utilizing lipid A adjuvant or anti-inflammatory properties in vaccinology.\n              <\/jats:p>\n            <\/jats:sec>\n          <\/jats:sec>","DOI":"10.1128\/msphere.00609-23","type":"journal-article","created":{"date-parts":[[2024,1,23]],"date-time":"2024-01-23T14:01:39Z","timestamp":1706018499000},"update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":1,"title":["Structural determination of\n            <i>Rickettsia<\/i>\n            lipid A without chemical extraction confirms shorter acyl chains in later-evolving spotted fever group pathogens"],"prefix":"10.1128","volume":"9","author":[{"given":"Hyojik","family":"Yang","sequence":"first","affiliation":[{"name":"Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, Maryland, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Victoria I.","family":"Verhoeve","sequence":"additional","affiliation":[{"name":"Department of Microbiology and Immunology, School of Medicine, University of Maryland, Baltimore, Maryland, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Courtney E.","family":"Chandler","sequence":"additional","affiliation":[{"name":"Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, Maryland, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Shreeram","family":"Nallar","sequence":"additional","affiliation":[{"name":"Division of Vaccine Research, Institute of Human Virology, University of Maryland, Baltimore, Maryland, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Greg A.","family":"Snyder","sequence":"additional","affiliation":[{"name":"Department of Microbiology and Immunology, School of Medicine, University of Maryland, Baltimore, Maryland, USA"},{"name":"Division of Vaccine Research, Institute of Human Virology, University of Maryland, Baltimore, Maryland, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5016-8694","authenticated-orcid":true,"given":"Robert K.","family":"Ernst","sequence":"additional","affiliation":[{"name":"Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, Maryland, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5447-7264","authenticated-orcid":true,"given":"Joseph J.","family":"Gillespie","sequence":"additional","affiliation":[{"name":"Department of Microbiology and Immunology, School of Medicine, University of Maryland, Baltimore, Maryland, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"235","reference":[{"key":"e_1_3_3_2_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41467-022-30385-6"},{"key":"e_1_3_3_3_2","doi-asserted-by":"publisher","DOI":"10.1093\/gigascience\/giab021"},{"key":"e_1_3_3_4_2","doi-asserted-by":"publisher","DOI":"10.1128\/mBio.00859-17"},{"key":"e_1_3_3_5_2","doi-asserted-by":"publisher","DOI":"10.1128\/mBio.01342-21"},{"key":"e_1_3_3_6_2","doi-asserted-by":"publisher","unstructured":"Figueroa-Cuilan WM Irazoki O Feeley M Smith E Nguyen T Cava F Goley ED. 2023. 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