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Effects of metabolic flux on stress response pathways in Lactococcus lactis
Author(s) -
Duwat Patrick,
Ehrlich S. Dusko,
Gruss Alexandra
Publication year - 1999
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.1999.01222.x
Subject(s) - lactococcus lactis , biology , mutant , context (archaeology) , gene , genetics , mutation , metabolic pathway , strain (injury) , microbiology and biotechnology , bacteria , lactic acid , paleontology , anatomy
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 isolatedthermoresistant insertionalmutants (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.