TABLE 2.
Genes of lactobacilli putatively involved in stress resistance studied by mutant analysis
Functional category | Gene or locus tag(s)a | Identification approachb | Putative function | Organism | Mutant phenotype | Reference(s) |
---|---|---|---|---|---|---|
Cell envelope | lr1516 | Microarray expression analysis | Putative esterase involved in PG biosynthesis and reorganization | L. reuteri ATCC 55730 | Increased sensitivity to acid and bile | 266, 277 |
LBA1272 | Dedicated approach | Cyclopropane fatty acid synthase | L. acidophilus NCFM | Increased sensitivity to acid | 127 | |
dltD | Dedicated approach | d-Alanylation of LTA | L. rhamnosus GG | Increased sensitivity to simulated gastric juice (pH 2), increased sensitivity to defensins | 188 | |
dltA | Dedicated approach | d-Alanylation of LTA | L. reuteri 100-23 | Decreased adaptation to acid, increased sensitivity to defensins | 270 | |
slpA | Dedicated approach | S-layer protein | L. acidophilus NCFM | Increased resistance to bile, decreased resistance to osmotic stress | 127 | |
cdpA | Comp. gen. (weak similarity to S-layer proteins) | Cell division and separation protein | L. acidophilus NCFM | Increased resistance to bile, decreased resistance to osmotic stress | 3, 127 | |
Protection and repair DNA and proteins | dps | Microarray expression analysis | DNA protection during starvation and other stresses | L. reuteri ATCC 55730 | No significantly increased sensitivity to bile | 277 |
clpL | Microarray expression analysis | Clp ATPase (chaperone) | L. reuteri ATCC 55730 | Increased sensitivity to acid and bile | 6, 277 | |
clpE | Microarray expression analysis | Clp ATPase (chaperone) | L. reuteri ATCC 55730 | No significantly increased sensitivity to bile | 277 | |
clpC | R-IVET | Clp ATPase (chaperone) | L. plantarum WCFS1 | Reduced persistence capacity in vivo | 31, 33 | |
msrB | IVET | Methionine sulfoxide reductase | L. reuteri 100-23 | Reduced persistence capacity in vivo | 268, 269 | |
luxS | Dedicated approach | Activated methyl cycle | L. rhamnosus GG | Reduced persistence capacity in vivo | 135 | |
2CRS regulators | LBA1524 | Comp.gen. (in silico) | Histidine protein kinase | L. acidophilus NCFM | Increased sensitivity to acid | 11 |
LBA1430* | Microarray expression analysis | Histidine protein kinase | L. acidophilus NCFM | Increased sensitivity to bile | 191 | |
LBA1431* | Microarray expression analysis | Response regulator | L. acidophilus NCFM | Increased sensitivity to bile | 191 | |
LBA1432* | Microarray expression analysis | Hypothetical protein with similarity to RelA/SpoT | L. acidophilus NCFM | Increased sensitivity to bile | 191 | |
rrp-1 | Dedicated approach | Response regulator | L. sakei 23K | Increased sensitivity to acid | 173 | |
rrp-48 | Dedicated approach | Response regulator | L. sakei 23K | Increased sensitivity to acid | 173 | |
Active removal of stressors | copA | R-IVET | Copper-transporting ATPase | L. plantarum WCFS1 | Reduced competitive ability in mouse intestine | 31, 33 |
gadC (LBA0057) | Comp.gen. (genome)c | Glutamate/γ-aminobutyrate antiporter | L. acidophilus NCFM | Increased sensitivity to acid | 10 | |
LBA0867 | Comp.gen. (genome)c | Transcriptional regulator | L. acidophilus NCFM | Increased sensitivity to acid and bile | 10 | |
LBA0995 | Comp.gen. (genome)c | Amino acid permease | L. acidophilus NCFM | Increased sensitivity to acid and bile | 10 | |
LBA0996 | Comp.gen. (genome)c | Ornithine decarboxylase | L. acidophilus NCFM | Increased sensitivity to acid but increased resistance to bile | 10 | |
Lr1265 | Microarray expression analysis | Multidrug resistance protein (ABC transporter family) | L. reuteri ATCC 55730 | Decreased adaptation to bile | 277 | |
Lr1584 | Microarray expression analysis | MDR protein (major facilitator family) | L. reuteri ATCC 55730 | Decreased adaptation to bile | 277 | |
LBA1427* | Microarray expression analysis | Putative oxidoreductase, role in bile salt modification? | L. acidophilus NCFM | Increased tolerance to bile | 191 | |
LBA1428* | Microarray expression analysis | Hypothetical protein with similarity to redox proteins, role in bile salt modification? | L. acidophilus NCFM | Increased tolerance to bile | 191 | |
LBA1429* | Microarray expression analysis | MDR protein (major facilitator family) | L. acidophilus NCFM | Increased sensitivity to bile | 191 | |
bshA | Comp.gen. (genome) | Bile salt hydrolase | L. acidophilus NCFM | Inability to hydrolyze bile salts conjugated to chenodeoxycholic acid; no altered bile tolerance | 165 | |
bshB | Comp.gen. (genome) | Bile salt hydrolase | L. acidophilus NCFM | Inability to hydrolyze bile salts conjugated to taurine; no altered bile tolerance | 165 | |
LJ0056, LJ1147, LJ1413 | Comp.gen. (genome) | Bile salt hydrolases | L. johnsonii NCC533 | A triple mutant showed gut persistence similar to that of the wild type | 67 | |
bsh1 | Comp.gen. (genome) | Bile salt hydrolase | L. plantarum WCFS1 | Reduced tolerance to glycodeoxycholic acid but not to taurodeoxycholic acid | 132 |
*, these genes are located in an operon in L. acidophilus NCFM (191).
Comp.gen., comparative genomics.
Genome, information based on genome sequence.