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Open Access Research

Functional identification in Lactobacillus reuteri of a PocR-like transcription factor regulating glycerol utilization and vitamin B12 synthesis

Filipe Santos126, Jennifer K Spinler34, Delphine MA Saulnier347, Douwe Molenaar12, Bas Teusink12, Willem M de Vos5, James Versalovic34 and Jeroen Hugenholtz26*

Author Affiliations

1 Center for Integrative Bioinformatics, Vrije Universiteit Amsterdam, Boelelaan 1085, 1081 HV Amsterdam, The Netherlands

2 TI Food and Nutrition, Kluyver Centre for Genomics of Industrial Fermentation, and NCSB, Nieuwe Kanaal 9A, 6709 PA, Wageningen, The Netherlands

3 Department of Pathology & Immunology, 1 Baylor Plaza, Baylor College of Medicine, Houston, TX 77030, USA

4 Department of Pathology, Texas Children's Hospital, 1102 Bates Avenue, Houston, TX 77030, USA

5 Laboratory of Microbiology, Wageningen University and Research Centre, Dreijenplein 10, 6703 HB Wageningen, The Netherlands

6 Department of Microbiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands

7 Current Address: NIZO Food Research, Ede, 6710 BA, the Netherlands

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Microbial Cell Factories 2011, 10:55  doi:10.1186/1475-2859-10-55

Published: 21 July 2011

Abstract

Background

Lactobacillus reuteri harbors the genes responsible for glycerol utilization and vitamin B12 synthesis within a genetic island phylogenetically related to gamma-Proteobacteria. Within this island, resides a gene (lreu_1750) that based on its genomic context has been suggested to encode the regulatory protein PocR and presumably control the expression of the neighboring loci. However, this functional assignment is not fully supported by sequence homology, and hitherto, completely lacks experimental confirmation.

Results

In this contribution, we have overexpressed and inactivated the gene encoding the putative PocR in L. reuteri. The comparison of these strains provided metabolic and transcriptional evidence that this regulatory protein controls the expression of the operons encoding glycerol utilization and vitamin B12 synthesis.

Conclusions

We provide clear experimental evidence for assigning Lreu_1750 as PocR in Lactobacillus reuteri. Our genome-wide transcriptional analysis further identifies the loci contained in the PocR regulon. The findings reported here could be used to improve the production-yield of vitamin B12, 1,3-propanediol and reuterin, all industrially relevant compounds.