Mycobacterial Gene cuvA Is Required for Optimal Nutrient Utilization and Virulence

Abstract

To persist and cause disease in the host, Mycobacterium tuberculosis must adapt to its environment during infection. Adaptations include changes in nutrient utilization and alterations in growth rate. M. tuberculosis Rv1422 is a conserved gene of unknown function that was found in a genetic screen to interact with the mce4 cholesterol uptake locus. The Rv1422 protein is phosphorylated by the M. tuberculosis Ser/Thr kinases PknA and PknB, which regulate cell growth and cell wall synthesis. Bacillus subtilis strains lacking the Rv1422 homologue yvcK grow poorly on several carbon sources, and yvcK is required for proper localization of peptidoglycan synthesis. Here we show that Mycobacterium smegmatis and M. tuberculosis strains lacking Rv1422 have growth defects in minimal medium containing limiting amounts of several different carbon sources. These strains also have morphological abnormalities, including shortened and bulging cells, suggesting a cell wall defect. In both mycobacterial species, the Rv1422 protein localizes uniquely to the growing cell pole, the site of peptidoglycan synthesis in mycobacteria. An M. tuberculosis ⌬Rv1422 strain is markedly attenuated for virulence in a mouse infection model, where it elicits decreased inflammation in the lungs and shows impaired bacterial persistence. These findings led us to name this gene cuvA (carbon utilization and virulence protein A) and to suggest a model in which deletion of cuvA leads to changes in nutrient uptake and/or metabolism that affect cell wall structure, morphology, and virulence. Its role in virulence suggests that CuvA may be a useful target for novel inhibitors of M. tuberculosis during infection.

The Listeria monocytogenes PASTA Kinase PrkA and Its Substrate YvcK Are Required for Cell Wall Homeostasis, Metabolism, and Virulence

“…subtilis YvcK is singly phosphorylated on a threonine residue near the C-terminus, but the site of phosphorylation is not precisely conserved [36,47]. Although the biochemical function of YvcK is unknown, like the PASTA kinases themselves, YvcK is important for both carbon metabolism and cell wall homeostasis [48–50]. In B .…”

“…subtilis and M . tuberculosis YvcK is required for growth on gluconeogenic substrates, pentose phosphate pathway/citric acid cycle intermediates and cholesterol, respectively [48,50]. Additionally, both B .…”

“…subtilis and M . tuberculosis ΔyvcK mutants display morphology defects under gluconeogenic growth conditions [48,50]. Although M .…”

“…tuberculosis CuvA localizes to the division septum and the poles, whereas B . subtilis YvcK localizes in a helical pattern, in both organisms CuvA/YvcK is required for Pbp1 localization under gluconeogenic growth conditions [49,50]. Finally, in B .…”

Metabolism Shapes the Cell

“…Another example of a connection between carbon metabolism and cell elongation is demonstrated by studies on YvcK. Homologs exist in a variety of bacteria (44)(45)(46), but YvcK is most extensively studied in B. subtilis (44,47,48). Although yvcK is not essential during growth in LB, cells with a yvcK deletion are round and lyse under gluconeogenic growth regimes, indicating a deficiency in elongasome function (44).…”