title: Microarray analysis of a two-component regulatory system involved in acid resistance and proteolytic activity in Lactobacillus acidophilus.
abstract: Two-component regulatory systems are one primary mechanism for environmental sensing and signal transduction. Annotation of the complete genome sequence of the probiotic bacterium Lactobacillus acidophilus NCFM revealed nine two-component regulatory systems. In this study, the histidine protein kinase of a two-component regulatory system (LBA1524HPK-LBA1525RR), similar to the acid-related system lisRK from Listeria monocytogenes (P. D. Cotter et al., J. Bacteriol. 181:6840-6843, 1999), was insertionally inactivated. A whole-genome microarray containing 97.4% of the annotated genes of L. acidophilus was used to compare genome-wide patterns of transcription at various pHs between the control and the histidine protein kinase mutant. The expression pattern of approximately 80 genes was affected by the LBA1524HPK mutation. Putative LBA1525RR target loci included two oligopeptide-transport systems present in the L. acidophilus genome, other components of the proteolytic system, and a LuxS homolog, suspected of participating in synthesis of the AI-2 signaling compound. The mutant exhibited lower tolerance to acid and ethanol in logarithmic-phase cells and poor acidification rates in milk. Supplementation of milk with Casamino Acids essentially restored the acid-producing ability of the mutant, providing additional evidence for a role of this two component system in regulating proteolytic activity in L. acidophilus.
authors.affiliation: Department of Food Science, North Carolina State University, Box 7624, Raleigh, NC 27695, USA.
authors.forename: M Andrea
authors.initials: MA
authors.lastname: Azcarate-Peril
authors.forename: Olivia
authors.initials: O
authors.lastname: McAuliffe
authors.forename: Eric
authors.initials: E
authors.lastname: Altermann
authors.forename: Sonja
authors.initials: S
authors.lastname: Lick
authors.forename: W Michael
authors.initials: WM
authors.lastname: Russell
authors.forename: Todd R
authors.initials: TR
authors.lastname: Klaenhammer
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D003470:Culture Media; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D000071677:Histidine Kinase; D006863:Hydrogen-Ion Concentration; D007779:Lactobacillus acidophilus / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D010447:Peptide Hydrolases / Q000235:genetics / Q000378:metabolism*; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D011494:Protein Kinases; D000071677:Histidine Kinase; D010447:Peptide Hydrolases