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Environmental interactions of Lactobacillus reuteri

signal transduction, gene expression and extracellular proteins of a lactic acid bacterium

Wall, Torun (2005). Environmental interactions of Lactobacillus reuteri. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis agriculturae Sueciae, 1652-6880 ; 2005:104
ISBN 91-576-6903-1
[Doctoral thesis]

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Abstract

The commensal bacterium Lactobacillus reuteri inhabits the human gastrointestinal tract and possesses putative probiotic, i.e. health-promoting, properties. In this thesis, features important for the ecological performance of L. reuteri and for interactions between the bacterium, its host and the environment were characterised. Extracellular proteins were identified in two L. reuteri strains. Firstly, fifty-three proteins were revealed in strain DSM 20016 using signal sequence phage display. Secondly, a draft genome sequence of strain ATCC 55730 was screened with bioinformatics tools and 126 genes encoding extracellular proteins were identified. Few obvious adhesion or colonisation factors were found, although an R28-like proteins putatively involved in adherence to mucosal surfaces was detected. The early response to sudden acid shock was studied with gene expression analyses using microarrays. When L. reuteri was exposed to an acidic pH, similar to the conditions in the human stomach, the chaperone-encoding clpA and genes putatively involved in cell envelope biogenesis were induced. Inactivation of clpA resulted in an acidic-sensitive phenotype. Seven complete two-component systems consisting of a histidine kinase and a response regulator were identified in the genome of L. reuteri ATCC 55730. Sequence analysis indicated that all seven systems belonged to the OmpR family. In order to expose the function of one of these systems, the response regulator was inactivated. The resulting mutant displayed increased sensitivity to NaCl and the antibiotic ampicillin. Results from gene expression analyses indicate that this two-component system regulates genes involved in cell envelope alterations in relation to stress. Therefore, this system was designated Lea (L. reuteri Envelope Altering). Taken together, these studies demonstrate the importance of the cell envelope for interactions between L. reuteri and its environment. The findings provide a basic insight in the adaptation mechanisms and the life strategies of this species. In addition, this work provides a foundation for further investigations and characterisation of the commensal bacterium L. reuteri.

Authors/Creators:Wall, Torun
Title:Environmental interactions of Lactobacillus reuteri
Subtitle:signal transduction, gene expression and extracellular proteins of a lactic acid bacterium
Year of publishing :November 2005
Volume:2005:104
Number of Pages:41
Papers/manuscripts:
NumberReferences
ALLI. Wall, T., Roos, S., Jacobsson, K., Rosander, A. & Jonsson, H. 2003. Phage display reveals 52 novel extracellular and transmembrane proteins from Lactobacillus reuteri DSM 20016T. Microbiology 149: 3493-3505. II. Båth, K., Roos, S., Wall, T. & Jonsson, H. 2005. The cell surface of Lactobacillus reuteri ATCC55730 highlighted by identification of 126 extracellular proteins from the genome sequence. FEMS Microbiology Letters (In press). III. Wall, T., Båth, K., Britton, RA., Jonsson, H., Versalovic, J. & Roos, S. The early response to acid shock in Lactobacillus reuteri involves the ClpA chaperone and cell surface alteration. (Manuscript). IV. Wall, T., Hüfner, E., Jonsson, H., Hertel, C. & Roos, S. Two-component signal transduction in Lactobacillus reuteri. (Manuscript).
Place of Publication:Uppsala
ISBN for printed version:91-576-6903-1
ISSN:1652-6880
Language:English
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:X Agricola extesions > X30 Life sciences
Subjects:Not in use, please see Agris categories
Agrovoc terms:lactobacillus, lactic acid bacteria, acids, proteins, gene expression, stress
Keywords:Lactobacillus reuteri, signal transduction, two-component system, stress, acid, extracellular proteins, lactic acid bacteria
URN:NBN:urn:nbn:se:slu:epsilon-791
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-791
ID Code:967
Department:(NL, NJ) > Dept. of Microbiology (until 161231)
Deposited By: Torun Wall
Deposited On:01 Nov 2005 00:00
Metadata Last Modified:02 Dec 2014 10:08

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