Affiliation:
1. Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland
2. Department of Microbiology, University College Cork, Cork, Ireland
3. Alimentary Pharmabiotic Centre, Cork, Ireland
Abstract
ABSTRACT
In this study, whole-genome microarrays were used to gain insights into the global molecular response of
Lactococcus lactis
subsp.
lactis
IL1403 at an early stage of infection with the lytic phage c2. The bacterium differentially regulated the expression of 61 genes belonging to 14 functional categories, including cell envelope processes (12 genes), regulatory functions (11 genes), and carbohydrate metabolism (7 genes). The nature of these genes suggests a complex response involving four main mechanisms: (i) induction of membrane stress proteins, (ii)
d
-alanylation of cell wall lipoteichoic acids (LTAs), (iii) maintenance of the proton motive force (PMF), and (iv) energy conservation. The phage presence is sensed as a membrane stress in
L. lactis
subsp.
lactis
IL1403, which activated a cell wall-targeted response probably orchestrated by the concerted action of membrane phage shock protein C-like homologues, the global regulator SpxB, and the two-component system CesSR. The bacterium upregulated genes (
ddl
and
dltABCD
) responsible for incorporation of
d
-alanine esters into LTAs, an event associated with increased resistance to phage attack in Gram-positive bacteria. The expression of genes (
yshC
,
citE
,
citF
) affecting both PMF components was also regulated to restore the physiological PMF, which was disrupted following phage infection. While mobilizing the response to the phage-mediated stress, the bacterium activated an energy-saving program by repressing growth-related functions and switching to anaerobic respiration, probably to sustain the PMF and the overall cell response to phage. To our knowledge, this represents the first detailed description in
L. lactis
of the molecular mechanisms involved in the host response to the membrane perturbations mediated by phage infection.
Publisher
American Society for Microbiology
Subject
Virology,Insect Science,Immunology,Microbiology
Cited by
56 articles.
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