Dataset Information

PBP2b plays a key role in both peripheral growth and septum positioning in Lactococcus lactis.

ABSTRACT: Lactococcus lactis is an ovoid bacterium that forms filaments during planktonic and biofilm lifestyles by uncoupling cell division from cell elongation. In this work, we investigate the role of the leading peptidoglycan synthase PBP2b that is dedicated to cell elongation in ovococci. We show that the localization of a fluorescent derivative of PBP2b remains associated to the septal region and superimposed with structural changes of FtsZ during both vegetative growth and filamentation indicating that PBP2b remains intimately associated to the division machinery during the whole cell cycle. In addition, we show that PBP2b-negative cells of L. lactis are not only defective in peripheral growth; they are also affected in septum positioning. This septation defect does not simply result from the absence of the protein in the cell growth machinery since it is also observed when PBP2b-deficient cells are complemented by a catalytically inactive variant of PBP2b. Finally, we show that round cells resulting from ?-lactam treatment are not altered in septation, suggesting that shape elongation as such is not a major determinant for selection of the division site. Altogether, we propose that the specific PBP2b transpeptidase activity at the septum plays an important role for tagging future division sites during L. lactis cell cycle.

SUBMITTER: David B

PROVIDER: S-EPMC5965867 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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PBP2b plays a key role in both peripheral growth and septum positioning in Lactococcus lactis.

David Blandine B Duchêne Marie-Clémence MC Haustenne Gabrielle Laurie GL Pérez-Núñez Daniel D Chapot-Chartier Marie-Pierre MP De Bolle Xavier X Guédon Eric E Hols Pascal P Hallet Bernard B

PloS one 20180523 5

Lactococcus lactis is an ovoid bacterium that forms filaments during planktonic and biofilm lifestyles by uncoupling cell division from cell elongation. In this work, we investigate the role of the leading peptidoglycan synthase PBP2b that is dedicated to cell elongation in ovococci. We show that the localization of a fluorescent derivative of PBP2b remains associated to the septal region and superimposed with structural changes of FtsZ during both vegetative growth and filamentation indicating ...[more]

PMID: 29791496

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Project description:The development of transcriptomic tools has allowed exhaustive description of stress responses. These responses always superimpose a general response associated to growth rate decrease and a specific one corresponding to the stress. The exclusive growth rate response can be achieved through chemostat cultivation, enabling all parameters to remain constant except the growth rate. We analysed metabolic and transcriptomic responses of Lactococcus lactis in continuous cultures at different growth rates ranging from 0.09 to 0.47 h-1. Growth rate was conditioned by isoleucine supply. Although the metabolism was constant and homolactic, a widespread transcriptomic response involving 30 % of the genome was observed. The expression of genes encoding physiological functions associated with biogenesis increased with growth rate (transcription, translation, fatty acid and phospholipids metabolism). Many phages, prophages and transposons related genes were down regulated by growth rate suggesting genome plasticity to be involved in the adaptation to slow growth. The growth rate response was compared to carbon and amino-acid starvation transcriptomic responses, revealing constant and significant involvement of growth rate regulations in these two stressful conditions (overlap 26%). Although stringent response mechanism is considered as the one governing growth deceleration in bacteria, the rigorous comparison of the two transcriptomic responses clearly indicated the mechanisms are distinct. Moreover it was established that genes positively regulated by growth rate are preferentially located in the vicinity of replication origin while those negatively regulated are mainly encountered at the opposite. This result demonstrates the often neglected relationship between genes expression and their location on chromosome. Keywords: growth rate impact, continuous cultures Continuous cultivation of Lactococcus lactis IL1403 were carried out on a chemically defined medium and under controlled conditions (30 Â°C, pH 6.6, nitrogen atmosphere). Cell samples were harvested at steady state. Total RNA was extracted from these samples and radiolabelled cDNA were prepared and hybridized on nylon arrays. 1948 amplicons specific of Lactococcus lactis IL1403 genes were spotted twice on the array. Samples corresponding to various growth rates were analyzed simultaneously and 3 independent repetitions were performed.

Dataset Information

PBP2b plays a key role in both peripheral growth and septum positioning in Lactococcus lactis.

Publications

PBP2b plays a key role in both peripheral growth and septum positioning in Lactococcus lactis.

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