title: Genomic and proteomic analysis of the Alkali-Tolerance Response (AlTR) in Listeria monocytogenes 10403S.
abstract: BACKGROUND
  Information regarding the Alkali-Tolerance Response (AlTR) in Listeria monocytogenes is very limited. Treatment of alkali-adapted cells with the protein synthesis inhibitor chloramphenicol has revealed that the AlTR is at least partially protein-dependent. In order to gain a more comprehensive perspective on the physiology and regulation of the AlTR, we compared differential gene expression and protein content of cells adapted at pH 9.5 and un-adapted cells (pH 7.0) using complementary DNA (cDNA) microarray and two-dimensional (2D) gel electrophoresis, (combined with mass spectrometry) respectively.
  
  
  RESULTS
  In this study, L. monocytogenes was shown to exhibit a significant AlTR following a 1-h exposure to mild alkali (pH 9.5), which is capable of protecting cells from subsequent lethal alkali stress (pH 12.0). Adaptive intracellular gene expression involved genes that are associated with virulence, the general stress response, cell division, and changes in cell wall structure and included many genes with unknown functions. The observed variability between results of cDNA arrays and 2D gel electrophoresis may be accounted for by posttranslational modifications. Interestingly, several alkali induced genes/proteins can provide a cross protective overlap to other types of stresses.
  
  
  CONCLUSIONS
  Alkali pH provides therefore L. monocytogenes with nonspecific multiple-stress resistance that may be vital for survival in the human gastrointestinal tract as well as within food processing systems where alkali conditions prevail. This study showed strong evidence that the AlTR in L. monocytogenes functions as to minimize excess alkalisation and energy expenditures while mobilizing available carbon sources.
authors.affiliation: Food Microbiology Research Group, University of Ulster, Northern Ireland, UK. stathis.giotis@bbsrc.ac.uk
authors.forename: Efstathios S
authors.initials: ES
authors.lastname: Giotis
authors.forename: Arunachalam
authors.initials: A
authors.lastname: Muthaiyan
authors.forename: Ian S
authors.initials: IS
authors.lastname: Blair
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Wilkinson
authors.forename: David A
authors.initials: DA
authors.lastname: McDowell
mesh_terms: D000468:Alkalies / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D008089:Listeria monocytogenes / Q000737:chemistry / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D013058:Mass Spectrometry; D020411:Oligonucleotide Array Sequence Analysis; D014176:Protein Biosynthesis / Q000187:drug effects; D040901:Proteomics
chemical_list: D000468:Alkalies; D001426:Bacterial Proteins