TABLE 3.

Genes identified by microarray analysis to be downregulated at 4°C in both log- and stationary-phase cellsa

Protein category and geneProtein functionbChange (n-fold) in cells grown toc:
Log phaseStationary phase
Virulence factors
    lmo0201 (plcA)Phosphatidylinositol-specific phospholipase C−8.3−8.8
    lmo0202 (hly)Listeriolysin O precursor−20.7−26.1
    lmo0205 (plcB)Phospholipase C−5.3−3.3
Heat shock proteins
    lmo2069 (groES)Class I heat shock protein (chaperonin) GroES−5.8−4.4
    lmo2068 (groEL)Class I heat shock protein (chaperonin) GroEL−5.7−3.1d
Metabolism
    lmo0210 (ldh)Similar to l-lactate dehydrogenase−4.0−3.8
Transcription or translation
    lmo0822Similar to transcriptional regulators−2.2−2.4
Other or hypothetical proteins
    lmo0104Unknown−2.6−3.7
    lmo0355Similar to flavocytochrome c fumarate reductase chain A−9.2−3.9
    lmo1219Unknown−2.5−4.8
    lmo2453Similar to lipolytic enzyme−2.1−5.5
  • a While only 10 genes met the stringent criteria for being downregulated at 4°C in both log- and stationary-phase cells (i.e., a ≥2-fold change and an adjusted P value of <0.001), 11 genes are listed here. groEL was included (even though groEL differential expression in stationary-phase cells did not meet the criterion of an adjusted P value of <0.001) as this gene is in the same operon as groES (which met the criteria of a ≥2-fold change and an adjusted P value of <0.001); all genes downregulated at 4°C in either log- or stationary-phase cells are listed in Tables S3 and S4 in the supplemental material.

  • b Protein functions are based on annotations provided by ListiList (http://genolist.pasteur.fr/ListiList/), TIGR (http://cmr.tigr.org/tigr-scripts/CMR/CmrHomePage.cgi), the NCBI (http://www.ncbi.nlm.nih.gov/), and the KEGG Sequence Similarity Database (http://www.genome.jp/kegg/ssdb/).

  • c Change (n-fold) indicates the transcript ratio between L. monocytogenes 10403S cells grown at 4°C and those grown at 37°C (as determined by microarray analysis); negative values indicate transcript levels that are lower at 4°C than at 37°C (e.g., a value of −8.6 indicates an 8.6-fold-lower transcript level at 4°C than at 37°C).

  • d For lmo2068 (groEL), differential transcription in stationary-phase cells was significant at an adjusted P value of <0.05 but not at an adjusted P value of <0.001.