Abstract
ABSTRACT
Mycobacterium tuberculosis
(Mtb) survives host defenses by adapting to host conditions, including acid stress, during infection. A critical survival strategy involves pH homeostasis, mediated by complex signaling systems that regulate metabolic reprogramming and stress responses. While the lysine acetyltransferase Rv0998 is known to support Mtb hypoxia adaptation and metabolic flexibility, its role in acid stress remains unexplored. Here, we investigated the consequences of
rv0998
deletion in 7H9 with glucose as the major carbon source. RNA-seq analysis showed that loss of Rv0998 altered the transcriptional response to acidic pH, including changes in the DosR regulon and
pfkB
/Rv2029c. Stable isotope tracing with [U-
13
C
6
]-glucose also showed reduced fractional
13
C labeling across central carbon metabolites in the
rv0998
mutant, with the largest decrease at acidic pH observed in upper glycolytic and connected hexose-phosphate intermediates. Growth and glucose-labeling phenotypes of
dosR
and
pfkB
mutants provided focused examples of stress-responsive and carbon-metabolic processes associated with the broader Rv0998 response. These findings indicate that Rv0998 contributes to coordinated transcriptional and metabolic adaptation of Mtb to acidic pH, and support further investigation of how stress-responsive regulatory programs are coupled to carbon metabolism during acid adaptation.
IMPORTANCE
Mycobacterium tuberculosis
(Mtb) persists in host environments that are both acidic and nutritionally variable, but the regulatory processes that connect these stresses to metabolism remain incompletely understood. We show that loss of the lysine acetyltransferase Rv0998 impairs growth at acidic pH when glucose is the major carbon source, and is accompanied by broad changes in gene expression and incorporation of glucose-derived carbon into central metabolites. The phenotype is not apparent when glycerol is also present, indicating that the response depends on carbon-source context. These findings identify Rv0998 as a contributor to the coordination of acid-stress adaptation and central carbon metabolism in Mtb, the bacterium that causes tuberculosis.