The synthesis of the bacteriocin sakacin A is a temperature-sensitive process regulated by a pheromone peptide through a three-component regulatory system.
Sakacin A is a bacteriocin produced by Lactobacillus sakei Lb706. The gene cluster (sap) encompasses a regulatory unit composed of three consecutive genes, orf4 and sapKR. sapKR encode a histidine protein kinase and a response regulator, while orf4 encodes the putative precursor of a 23-amino-acid cationic peptide (termed Sap-Ph). The authors show that Sap-Ph serves as a pheromone regulating bacteriocin production. Lb706 produced bacteriocin when the growth temperature was kept at 25 or 30 degrees C, but production was reduced or absent at higher temperatures (33.5-35 degrees C). Production was restored by lowering the growth temperature to 30 degrees C, but at temperatures of 33-34 degrees C also by adding exogenous Sap-Ph to the growth medium. A knock-out mutation in orf4 abolished sakacin A production. Exogenously added Sap-Ph complemented this mutation, unambiguously showing the essential role of this peptide for bacteriocin production. Another sakacin A producer, Lactobacillus curvatus LTH1174, had a similar response to temperature and exogenously added Sap-Ph.
Diep
Dzung B
DB
Laboratory for Microbial Gene Technology, Department of Biotechnological Sciences, Agricultural University of Norway, PO Box 5051,N-1432 Ås, Norway1.
Axelsson
Lars
L
MATFORSK, Norwegian Food Research Institute, Osloveien 1, N-1430 Ås, Norway2.
Grefsli
Camilla
C
Laboratory for Microbial Gene Technology, Department of Biotechnological Sciences, Agricultural University of Norway, PO Box 5051,N-1432 Ås, Norway1.
Nes
Ingolf F
IF
Laboratory for Microbial Gene Technology, Department of Biotechnological Sciences, Agricultural University of Norway, PO Box 5051,N-1432 Ås, Norway1.
D000595:Amino Acid Sequence; D001430:Bacteriocins / Q000096:biosynthesis* / Q000235:genetics*; D001483:Base Sequence; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D000071677:Histidine Kinase; D007778:Lactobacillus / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D008969:Molecular Sequence Data; D005810:Multigene Family; D016366:Open Reading Frames / Q000235:genetics; D010675:Pheromones / Q000378:metabolism* / Q000494:pharmacology; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism; D013696:Temperature
D001430:Bacteriocins; D010675:Pheromones; D011498:Protein Precursors; C071456:sakacin A; D011494:Protein Kinases; D000071677:Histidine Kinase