- The role of intestinal bacteria in health and disease
- Recombineering in lactic acid bacteria
- GTPase control of ribosome assembly
1. The role of intestinal bacteria in health and disease.
Recent work into the role of intestinal bacteria in a variety of disease states including inflammatory bowel disease, obesity, and diabetes has established a clear link between these bacteria and our health. The Britton laboratory is focused on two areas of research in this area: the role of probiotic bacteria in treating disease and the role of the intestinal microbiota in preventing pathogen invasion.
Probiotic Lactobacillus reuteri
Much of our work focuses on characterizing how different strains of Lactobacillus reuteri impact various aspects of the host response including inflammation, bone health, pathogen invasion and intestinal function. We use a variety of in vitro and animal models to explore how L. reuteri impacts health. Our overall goals are to identify novel probiotic strains that can be used to prevent or ameliorate disease and to develop a platform for the delivery of biotherapeutics.
Jones SE, Whitehead K, Saulnier D, Thomas CM, Versalovic J, Britton RA. (2011). Cyclopropane fatty acid synthase mutants of probiotic human-derived Lactobacillus reuteri are defective in TNF inhibition. Gut Microbes. 2:69-79
Walter J, Britton RA, and Roos S. (2011) Microbes and Health Sackler Colloquium: Host-microbial symbiosis in the vertebrate gastrointestinal tract and the Lactobacillus reuteri paradigm. PNAS. Epub June 25, 2010. Suppl 1:4645-52.
Schaefer L, Auchtung TA, Hermans KE, Whitehead D, Borhan B, Britton RA. (2010). The antimicrobial compound reuterin (3-hydroxypropionaldehyde) induces oxidative stress via interaction with thiol groups. Microbiology. 156:1589-1599.
Thomas, CM, Hong, T, van Pijkeren, JP, Hemerajata, P, Trinh, DV, Hu, W, Britton, RA, Kalkum, M, and Versalovic, J (2012). Histamine derived from probiotic Lactobacillus reuteri suppresses TNF via modulation of PKA and ERK signaling. PLoS One. 2012;7(2):e31951. Epub 2012 Feb 22.
Eaton KA, Honkala A, Auchtung TA, Britton RA. (2011). Probiotic Lactobacillus reuteri ameliorates disease due to Enterohemorrhagic Escherichia coli in germ free mice. Infection and Immunity. Jan;79(1):185-91. Epub 2010 Oct 25.
Microbiota and prevention of pathogen invasion.
We are interested in understanding how the intestinal microbiota provides a barrier to incoming pathogens and how perturbations of the microbiota result in an established infection. We have focused most of our attention on the pathogen Clostridium difficile, which is the most common cause of antibiotic associated diarrhea and is quickly becoming the most common cause of nosocomial infections. We have developed mini-bioreactors and mice colonized with a human intestinal microbiota to address which members of the community are responsible for inhibiting C. difficile invasion. Our ultimate goal is to develop a probiotic cocktail derived from the human intestinal microbiota that will suppress C. difficile invasion.
This project is funded by the NIH Enteric Research Investigative Network (ERIN). The Michigan State University ERIN is directed by Linda Mansfield with myself and Shannon Manning as project leaders.
Britton, RA and Young, VB. (2012). Interaction between the intestinal microbiota and host in Clostridium difficile colonization resistance. Trends in Microbiology. 7:313-19.
Britton, RA and Versalovic, J. (2009). Probiotics and gastrointestinal infections. Interdisciplinary Perspectives in Infectious Disease. 2008:290769. Epub 2009 Feb 4.
Collaborators: Much of the work we do is interdisciplinary and thus we engage in a number of collaborative projects. Our collaborators include Laura McCabe (Michigan State University), Nara Parameswaran (Michigan State University), Vincent Young (University of Michigan), James Versalovic (Baylor College of Medicine), Stefan Roos (Swedish University of Agricultural Sciences), Eamonn Connolly (Biogaia AB), Linda Mansfield (Michigan State University), Shannon Manning (Michigan State University), Kathryn Eaton (University of Michigan).
2. Recombineering in lactic acid bacteria. Recombineering technology allows for the precise genetic manipulation of bacterial chromosomes. Using single-stranded DNA (ssDNA) recombineering technology point mutations, small deletions, and small insertions can be recovered without the need for selection. Previous to our recent work, non-selected ssDNA recombineering could only be performed in Escherichia coli. We have now established non-selected recombineering in two lactic acid bacteria strains, Lactobacillus reuteri and Lactococcus lactis. We also have shown that recombineering can function in other Gram-positive bacteria as well. We can achieve average recombineering efficiencies of ~15% in L. lactis, which will now enable directed evolution of multiple chromosomal sites to be achieved simultaneously. Finally, we have also developed an efficient method for inserting genes stably into the chromosome of L. reuteri, which will enable the use of this human-derived organism to be used in the intestinal delivery of biotherapeutics and vaccines.L. reuteri.
van Pijkeren, JP and Britton RA. (2012). High-efficiency recombineering in lactic acid bacteria. Nucleic Acids Research. 2012 May;40(10):e76. Epub 2012 Feb 10 2012.
van Pijkeren JP, Neoh KM, Sirias D, Findley AS, Britton RA (2012). Exploring optimization parameters to increase ssDNA recombineering in Lactococcus lactis and Lactobacillus reuteri. Bioengineered Bugs. 3(4). [Epub ahead of print].
3. GTPase control of ribosome assembly. GTPases play an important role in the assembly of ribosomes in all three kingdoms of life. The molecular mechanisms by which they function are largely unknown. We are studying the ribosome assembly GTPase RbgA in Bacillus subtilis in an attempt to understand how these proteins act in the maturation of the large ribosomal subunit using a combination of biochemical, structural and genetic approaches. Interestingly, mutation or depletion of RbgA results in the accumulation of a ribosome assembly intermediate that is arrested at a very late stage of development. Work on eukaryotic homologs of RbgA suggests that these proteins are involved in a late assembly step of the large ribosomal subunit. The results from this bacterial work will have important implications for the formation of cytoplasmic, mitochondrial, and chloroplast ribosomes.
Collaborator: Joaquin Ortega (McMaster University).
Uicker, WU, Schaefer, L and Britton, RA (2006). The essential GTPase RbgA (YlqF) is required for 50S ribosome assembly in Bacillus subtilis. Molecular Microbiology. 59:528-40. Published online ahead of print Nov. 3, 2005.
Schaefer, L, Uicker, WU, Wicker-Planquart, C, Foucher, AE, Jault JM and Britton, RA (2006). Multiple GTPases participate in the assembly of the large ribosomal subunit in Bacillus subtilis. Journal of Bacteriology. 188:8252-8258.
Britton, RA, Schaefer, L, Wen, T, Pellegrini, O, Uicker, WC, Tobin, C, Mathy, N, Daou, R, Szyk, Y, and Condon, C (2007). Maturation of the 5Ã¢â‚¬â„¢-end of B. subtilis 16S rRNA by YkqC (RNase J1). Molecular Microbiology. 63:127-38.
Uicker, WC, Schaefer, L, Koenigsknecht, M, and Britton, RA (2007). The essential GTPase YqeH is required for proper ribosome assembly in Bacillus subtilis. Journal of Bacteriology. 189:2926-29.
Britton, RA. Role of GTPases in ribosome assembly. (2009). Annual Review of Microbiology. 2009;63:155-76.
Achila D, Gulati M, Jain N, Britton RA. (2012). Biochemical characterization of the ribosome assembly GTPase RbgA in Bacillus subtilis. Journal of Biological Chemistry. 153:564-73.
We are grateful to the following funding agencies for current and past support of our research: NIH, NSF, DARPA, Michigan State University Foundation, Gerber Foundation, Michigan State University Vice President for Research Office, Biogaia AB, Christian Hansen, Novozymes, Procter and Gamble, Michigan State University Department of Microbiology and Molecular Genetics.