Identification of key peptidoglycan hydrolases for morphogenesis, autolysis, and peptidoglycan composition of Lactobacillus plantarum WCFS1

Microbial Cell Factories

Research

Pascal Hols¹  Thomas Rolain¹  Elvis Bernard²  Pascal Courtin³  Marie-Pierre Chapot-Chartier³  Michiel Kleerebezem⁴  Peter A Bron⁵ 

[1] Biochimie et Génétique Moléculaire Bactérienne, Institut des Sciences de la Vie, Université catholique de Louvain, Place Croix du Sud 5/L7.07.06, B-1348, Louvain-la-Neuve, Belgium;Biochimie et Génétique Moléculaire Bactérienne, Institut des Sciences de la Vie, Université catholique de Louvain, Place Croix du Sud 5/L7.07.06, B-1348, Louvain-la-Neuve, Belgium;INRA, UMR1319 Micalis, Jouy-en-Josas, F-78350, France;AgroParisTech, UMR Micalis, Jouy-en-Josas, F-78350, France;INRA, UMR1319 Micalis, Jouy-en-Josas, F-78350, France;AgroParisTech, UMR Micalis, Jouy-en-Josas, F-78350, France;TI Food & Nutrition, Nieuwe Kanaal 9A, 6709, Wageningen, PA, The Netherlands;NIZO food research, Kernhemseweg 2, 6718, EdeThe Netherlands, ZB;Host Microbe Interactomics Group, Wageningen University, De Elst 1, 6708, Wageningen, WD, The Netherlands;TI Food & Nutrition, Nieuwe Kanaal 9A, 6709, Wageningen, PA, The Netherlands;NIZO food research, Kernhemseweg 2, 6718, EdeThe Netherlands, ZB;Kluyver Centre for Genomics of Industrial Fermentation, Julianalaan 67, 2628, DelftThe Netherlands, BC;

关键词: Lactobacillus plantarum;    Peptidoglycan;    Autolysin;    Peptidoglycan hydrolase;    Glucosaminidase;    Muropeptidase;   

DOI  :  10.1186/1475-2859-11-137

 received in 2012-06-14, accepted in 2012-10-03,  发布年份 2012

来源: Springer

【 摘 要 】

BackgroundLactobacillus plantarum is commonly used in industrial fermentation processes. Selected strains are also marketed as probiotics for their health beneficial effects. Although the functional role of peptidoglycan-degrading enzymes is increasingly documented to be important for a range of bacterial processes and host-microbe interactions, little is known about their functional roles in lactobacilli. This knowledge holds important potential for developing more robust strains resistant to autolysis under stress conditions as well as peptidoglycan engineering for a better understanding of the contribution of released muramyl-peptides as probiotic immunomodulators.ResultsHere, we explored the functional role of the predicted peptidoglycan hydrolase (PGH) complement encoded in the genome of L. plantarum by systematic gene deletion. From twelve predicted PGH-encoding genes, nine could be individually inactivated and their corresponding mutant strains were characterized regarding their cell morphology, growth, and autolysis under various conditions. From this analysis, we identified two PGHs, the predicted N-acetylglucosaminidase Acm2 and NplC/P60 D,L-endopeptidase LytA, as key determinants in the morphology of L. plantarum. Acm2 was demonstrated to be required for the ultimate step of cell separation of daughter cells, whereas LytA appeared to be required for cell shape maintenance and cell-wall integrity. We also showed by autolysis experiments that both PGHs are involved in the global autolytic process with a dominant role for Acm2 in all tested conditions, identifying Acm2 as the major autolysin of L. plantarum WCFS1. In addition, Acm2 and the putative N-acetylmuramidase Lys2 were shown to play redundant roles in both cell separation and autolysis under stress conditions. Finally, the analysis of the peptidoglycan composition of Acm2- and LytA-deficient derivatives revealed their potential hydrolytic activities by the disappearance of specific cleavage products.ConclusionIn this study, we showed that two PGHs of L. plantarum have a predominant physiological role in a range of growth conditions. We demonstrate that the N-acetylglucosaminidase Acm2 is the major autolysin whereas the D,L-endopeptidase LytA is a key morphogenic determinant. In addition, both PGHs have a direct impact on PG structure by generating a higher diversity of cleavage products that could be of importance for interaction with the innate immune system.

【 授权许可】

Unknown   
© Rolain et al.; licensee BioMed Central Ltd. 2012. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.