HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Supplementary Figures Errata Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Hamze, K. Articles by Séror, S. J. Search for Related Content PubMed PubMed Citation Articles by Hamze, K. Articles by Séror, S. J. Agricola Articles by Hamze, K. Articles by Séror, S. J.

Identification of genes required for different stages of dendritic swarming in Bacillus subtilis, with a novel role for phrC

Daria Julkowska

Sabine Autret

Krzysztof Hinc

Krzysztofa Nagorska

Université Paris-Sud, Institut de Génétique et Microbiologie, UMR CNRS 8621, Bât. 409, 91405 Orsay Cedex, France

Correspondence
Simone J. Séror
simone.seror{at}igmors.u-psud.fr

Highly branched dendritic swarming of B. subtilis on synthetic B-medium involves a developmental-like process that is absolutely dependent on flagella and surfactin secretion. In order to identify new swarming genes, we targeted the two-component ComPA signalling pathway and associated global regulators. In liquid cultures, the histidine kinase ComP, and the response regulator ComA, respond to secreted pheromones ComX and CSF (encoded by phrC) in order to control production of surfactin synthases and ComS (competence regulator). In this study, for what is believed to be the first time, we established that distinct early stages of dendritic swarming can be clearly defined, and that they are amenable to genetic analysis. In a mutational analysis producing several mutants with distinctive phenotypes, we were able to assign the genes sfp (activation of surfactin synthases), comA, abrB and codY (global regulators), hag (flagellin), mecA and yvzB (hag-like), and swrB (motility), to the different swarming stages. Surprisingly, mutations in genes comPX, comQ, comS, rapC and oppD, which are normally indispensable for import of CSF, had only modest effects, if any, on swarming and surfactin production. Therefore, during dendritic swarming, surfactin synthesis is apparently subject to novel regulation that is largely independent of the ComXP pathway; we discuss possible alternative mechanisms for driving srfABCD transcription. We showed that the phrC mutant, largely independent of any effect on surfactin production, was also, nevertheless, blocked early in swarming, forming stunted dendrites, with abnormal dendrite initiation morphology. In a mixed swarm co-inoculated with phrC sfp⁺ and phrC⁺ sfp (GFP), an apparently normal swarm was produced. In fact, while initiation of all dendrites was of the abnormal phrC type, these were predominantly populated by sfp cells, which migrated faster than the phrC cells. This and other results indicated a specific migration defect in the phrC mutant that could not be trans-complemented by CSF in a mixed swarm. CSF is the C-terminal pentapeptide of the surface-exposed PhrC pre-peptide and we propose that the residual PhrC 35 aa residue peptide anchored in the exterior of the cytoplasmic membrane has an apparently novel extracellular role in swarming.

Present address: Laboratoire de Génétique Microbienne, INRA, Domaine de Vilvert, 78352 Jouy en Josas Cedex, France.

Present address: Medical University of Gdansk, Debinki 1 80-211, Department of Medical Biotechnology, Intercollegiate Faculty of Biotechnology, Gdansk, Poland.

||Present address: Unité de Génétique des Génomes Bactériens, Institut Pasteur, 28 rue du Docteur Roux, 75724 Paris Cedex 15, France.

Supplementary figures showing a scheme of regulatory circuits controlling surfactin production and competence expression in liquid cultures, and surfactin-independent swarming patterns on LB are available with the online version of this paper.

This article has been cited by other articles:

				J. E. Patrick and D. B. Kearns Laboratory Strains of Bacillus subtilis Do Not Exhibit Swarming Motility J. Bacteriol., November 15, 2009; 191(22): 7129 - 7133. [Abstract] [Full Text] [PDF]