期刊
SCIENTIFIC REPORTS
卷 5, 期 -, 页码 -出版社
NATURE PUBLISHING GROUP
DOI: 10.1038/srep16198
关键词
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资金
- Ministerio de Ciencia e Innovacion (MICINN)
- Ministerio de Economia y Competitividad (MINECO) [SAF2009-10824, SAF2012-39444-C02-01, BFU2009-10052, BFU2012-36825]
- Consejeria de Educacion de la Comunidad de Madrid [S2010/BMD/2457]
- BBSRC [BB/G015902/1]
- National Institutes of Health [GM61629]
- CIBER de Enfermedades Respiratorias (CIBERES)
- initiative of the Instituto de Salud Carlos III (ISCIII)
- MICINN (FPI program)
- Biotechnology and Biological Sciences Research Council [BB/G015902/1] Funding Source: researchfish
- BBSRC [BB/G015902/1] Funding Source: UKRI
Streptococcus pneumoniae is a major cause of life-threatening diseases worldwide. Here we provide an in-depth functional characterization of LytB, the peptidoglycan hydrolase responsible for physical separation of daughter cells. Identified herein as an N-acetylglucosaminidase, LytB is involved also in colonization and invasion of the nasopharynx, biofilm formation and evasion of host immunity as previously demonstrated. We have shown that LytB cleaves the GlcNAc-beta-(1,4)-MurNAc glycosidic bond of peptidoglycan building units. The hydrolysis occurs at sites with fully acetylated GlcNAc moieties, with preference for uncross-linked muropeptides. The necessity of GlcN acetylation and the presence of a single acidic moiety (Glu585) essential for catalysis strongly suggest a substrate-assisted mechanism with anchimeric assistance of the acetamido group of GlcNAc moieties. Additionally, modelling of the catalytic region bound to a hexasaccharide tripentapeptide provided insights into substrate-binding subsites and peptidoglycan recognition. Besides, cell-wall digestion products and solubilisation rates might indicate a tight control of LytB activity to prevent unrestrained breakdown of the cell wall. Choline-independent localization at the poles of the cell, mediated by the choline-binding domain, peptidoglycan modification, and choline-mediated (lipo) teichoic-acid attachment contribute to the high selectivity of LytB. Moreover, so far unknown chitin hydrolase and glycosyltransferase activities were detected using GlcNAc oligomers as substrate.
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