title: SpoVT: From Fine-Tuning Regulator inBacillus subtilisto Essential Sporulation Protein inBacillus cereus.
abstract: Sporulation is a highly sophisticated developmental process adopted by most Bacilli as a survival strategy to withstand extreme conditions that normally do not support microbial growth. A complicated regulatory cascade, divided into various stages and taking place in two different compartments of the cell, involves a number of primary and secondary regulator proteins that drive gene expression directed toward the formation and maturation of an endospore. Such regulator proteins are highly conserved among various spore formers. Despite this conservation, both regulatory and phenotypic differences are observed between different species of spore forming bacteria. In this study, we demonstrate that deletion of the regulatory sporulation protein SpoVT results in a severe sporulation defect inBacillus cereus, whereas this is not observed inBacillus subtilis. Although spores are initially formed, the process is stalled at a later stage in development, followed by lysis of the forespore and the mother cell. A transcriptomic investigation ofB. cereusΔspoVTshows upregulation of genes involved in germination, potentially leading to premature lysis of prespores formed. Additionally, extreme variation in the expression of species-specific genes of unknown function was observed. Introduction of theB. subtilisSpoVT protein could partly restore the sporulation defect in theB. cereus spoVTmutant strain. The difference in phenotype is thus more than likely explained by differences in promoter targets rather than differences in mode of action of the conserved SpoVT regulator protein. This study stresses that evolutionary variances in regulon members of sporulation regulators can have profound effects on the spore developmental process and that mere protein homology is not a foolproof predictor of similar phenotypes.
authors: Top Institute Food and NutritionWageningen, Netherlands; Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of GroningenGroningen, Netherlands.
authors: Robyn T
authors: RT
authors: Eijlander
authors: Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen Groningen, Netherlands.
authors: Siger
authors: S
authors: Holsappel
authors: Top Institute Food and NutritionWageningen, Netherlands; Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of GroningenGroningen, Netherlands.
authors: Anne
authors: A
authors: de Jong
authors: Department of Chemical Engineering and Biotechnology, Institute of Biotechnology, University of Cambridge Cambridge, UK.
authors: Abhinaba
authors: A
authors: Ghosh
authors: Department of Chemical Engineering and Biotechnology, Institute of Biotechnology, University of Cambridge Cambridge, UK.
authors: Graham
authors: G
authors: Christie
authors: Top Institute Food and NutritionWageningen, Netherlands; Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of GroningenGroningen, Netherlands.
authors: Oscar P
authors: OP
authors: Kuipers
keywords: Bacillus cereus; SpoVT; gene regulation; germination; sporulation