{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,21]],"date-time":"2026-02-21T03:52:51Z","timestamp":1771645971986,"version":"3.50.1"},"reference-count":0,"publisher":"SAGE Publications","issue":"4","license":[{"start":{"date-parts":[[2001,12,1]],"date-time":"2001-12-01T00:00:00Z","timestamp":1007164800000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.sagepub.com\/page\/policies\/text-and-data-mining-license"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Microbial Drug Resistance"],"published-print":{"date-parts":[[2001,12]]},"abstract":"<jats:p>\n                    The recently identified\n                    <jats:italic toggle=\"yes\">murMN<\/jats:italic>\n                    operon is essential for the production of branched-structured muropeptides in the cell wall and also for the expression of the resistant phenotype in penicillin-resistant\n         strains of\n                    <jats:italic toggle=\"yes\">Streptococcus pneumoniae<\/jats:italic>\n                    . The purpose of studies described in this communication was to understand better the role of\n                    <jats:italic toggle=\"yes\">murMN<\/jats:italic>\n                    in penicillin resistance. Deletion of\n                    <jats:italic toggle=\"yes\">murM<\/jats:italic>\n                    in\n         the penicillin-resistant strain Pen6, which causes reduction in the penicillin MIC from 6.0 to 0.03\n                    <jats:italic toggle=\"yes\">\u03bc<\/jats:italic>\n                    g\/ml, was successfully complemented to recover the original high level of penicillin resistance\n         in transformants that received functional\n                    <jats:italic toggle=\"yes\">murM<\/jats:italic>\n                    alleles cloned in plasmid pLS578. Inactivation of penicillin resistance was not accompanied by any detectable change in the low affinity or abnormal\n         molecular size pattern of the penicillin-binding proteins (PBPs) nor in the mosaic sequence of PBP2X typical of resistant strain Pen6. Exposure of strain Pen6 with inactivated\n                    <jats:italic toggle=\"yes\">murM<\/jats:italic>\n                    to 0.05\n                    <jats:italic toggle=\"yes\">\u03bc<\/jats:italic>\n                    g\/ml\n         of penicillin (\n                    <jats:italic toggle=\"yes\">i.e.<\/jats:italic>\n                    , a concentration more than 100 times below the MIC of the parental strain) initiated a phenotypic response typical of penicillin-susceptible strains of pneumococci: inhibition\n         of growth followed by rapid and extensive loss of viability and lysis. Unexpectedly, inactivation of\n                    <jats:italic toggle=\"yes\">murMN<\/jats:italic>\n                    also caused hypersensitivity to lysis by low concentrations of a variety of cell wall active\n         antibiotics such as fosfomycin, D-cycloserine, and nisin, suggesting that the\n                    <jats:italic toggle=\"yes\">murMN<\/jats:italic>\n                    operon may perform an important regulatory role in the control of the irreversible antimicrobial effects of cell\n         wall inhibitors.\n                  <\/jats:p>","DOI":"10.1089\/10766290152773310","type":"journal-article","created":{"date-parts":[[2002,7,26]],"date-time":"2002-07-26T18:08:35Z","timestamp":1027706915000},"page":"303-316","source":"Crossref","is-referenced-by-count":29,"title":["The Role of\n                    <i>murMN<\/i>\n                    Operon in Penicillin Resistance and Antibiotic Tolerance of\n                    <i>Streptococcus pneumoniae<\/i>"],"prefix":"10.1177","volume":"7","author":[{"given":"Sergio R.","family":"Filipe","sequence":"first","affiliation":[{"name":"Laboratory of Microbiology, The Rockefeller University, New York, New York 10021 and Molecular Genetics Unit, Instituto de Tecnologia Qu\u00edmica e Biol\u00f3gica, Universidade Nova de Lisboa 2780, Oeiras, Portugal"}]},{"given":"Elena","family":"Severina","sequence":"additional","affiliation":[{"name":"Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142292 Russia"}]},{"given":"Alexander","family":"Tomasz","sequence":"additional","affiliation":[{"name":"Laboratory of Microbiology, The Rockefeller University, New York, New York 10021"}]}],"member":"179","published-online":{"date-parts":[[2001,12]]},"container-title":["Microbial Drug Resistance"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/journals.sagepub.com\/doi\/pdf\/10.1089\/10766290152773310","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/journals.sagepub.com\/doi\/pdf\/10.1089\/10766290152773310","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,2,10]],"date-time":"2026-02-10T18:13:57Z","timestamp":1770747237000},"score":1,"resource":{"primary":{"URL":"https:\/\/journals.sagepub.com\/doi\/full\/10.1089\/10766290152773310"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2001,12]]},"references-count":0,"journal-issue":{"issue":"4","published-print":{"date-parts":[[2001,12]]}},"alternative-id":["10.1089\/10766290152773310"],"URL":"https:\/\/doi.org\/10.1089\/10766290152773310","relation":{},"ISSN":["1076-6294","1931-8448"],"issn-type":[{"value":"1076-6294","type":"print"},{"value":"1931-8448","type":"electronic"}],"subject":[],"published":{"date-parts":[[2001,12]]}}}