Effects of metabolic flux on stress response pathways in Lactococcus lactis.

Abstract	Studies of cellular responses to stress conditions such as heat, oxygen or starvation have revealed the existence of numerous specific or interactive response pathways. We previously observed in Lactococcus lactis that inactivation of the recA gene renders the lactococcal strain sensitive not only to DNA-damaging agents but also to oxygen and heat. To further examine the stress response pathways in L. lactis, we isolated thermoresistant insertional mutants (Trm) of the recA strain. Eighteen independent trm mutations were identified and characterized. We found that mutations map in only seven genes, implicated in purine metabolism (deoB, guaA and tktA), phosphate uptake (pstB and pstS), mRNA stability (pnpA) and in one uncharacterized gene (trmA). All the trm mutations, with the exception of trmA, confer multiple stress resistance to the cell. Some of the mutations confer improved heat stress resistance not only in the recA but also in the wild-type context. Our results reveal that cellular metabolic pathways are intimately related to stress response and that the flux of particular metabolites, notably guanine and phosphate, may be implicated in stress response in lactococci.
Authors	P Duwat, S D Ehrlich, A Gruss
Journal	Molecular microbiology (Mol Microbiol) Vol. 31 Issue 3 Pg. 845-58 (Feb 1999) ISSN: 0950-382X [Print] England
PMID	10048028 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
Chemical References	ATP-Binding Cassette Transporters Escherichia coli Proteins Guanine Nucleotides Heat-Shock Proteins Periplasmic Binding Proteins Phosphate-Binding Proteins Phosphates PstS protein, E coli Guanosine Xanthine Hypoxanthine Inosine Guanine Carbon Hydrogen Peroxide Rec A Recombinases
Topics	ATP-Binding Cassette Transporters (genetics) Carbon (physiology) Cell Survival Escherichia coli Proteins Genes, Bacterial Guanine (pharmacology) Guanine Nucleotides (physiology) Guanosine (pharmacology) Heat-Shock Proteins (genetics, physiology) Hydrogen Peroxide (pharmacology) Hypoxanthine (pharmacology) Inosine (pharmacology) Lactococcus lactis (genetics, physiology) Metabolism (physiology) Molecular Sequence Data Mutagenesis, Insertional Periplasmic Binding Proteins Phosphate-Binding Proteins Phosphates (pharmacology) Rec A Recombinases (genetics) Temperature Time Factors Xanthine (pharmacology)

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