Pyruvate kinase plays a central role in glucose catabolism in bacteria, and efficient utilization of this hexose has been linked to the virulence of Brucella strains in mice. The brucellae produce a single pyruvate kinase which is an ortholog of the Bradyrhizobium manganese (Mn)-dependent pyruvate kinase PykM. A biochemical analysis of the Brucella pyruvate kinase and phenotypic analysis of a Brucella abortus mutant defective in high-affinity Mn import indicate that this enzyme is an authentic PykM ortholog which functions as a Mn-dependent enzyme in vivo. The loss of PykM has a negative impact on the capacity of the parental 2308 strain to utilize glucose, fructose, and galactose but not on its ability to utilize ribose, xylose, arabinose, or erythritol, and a pykM mutant displays significant attenuation in C57BL/6 mice. Although the enzyme pyruvate phosphate dikinase (PpdK) can substitute for the loss of pyruvate kinase in some bacteria and is also an important virulence determinant in Brucella, a phenotypic analysis of B. abortus 2308 and isogenic pykM, ppdK, and pykM ppdK mutants indicates that PykM and PpdK make distinctly different contributions to carbon metabolism and virulence in these bacteria. IMPORTANCE Mn plays a critical role in the physiology and virulence of Brucella strains, and the results presented here suggest that one of the important roles that the high-affinity Mn importer MntH plays in the pathogenesis of these strains is supporting the function of the Mn-dependent kinase PykM. A better understanding of how the brucellae adapt their physiology and metabolism to sustain their intracellular persistence in host macrophages will provide knowledge that can be used to design improved strategies for preventing and treating brucellosis, a disease that has a significant impact on both the veterinary and public health communities worldwide. Citation Pitzer JE, Zeczycki TN, Baumgartner JE, Martin DW, Roop RM, II. 2018. The manganesedependent pyruvate kinase PykM is required for wild-type glucose utilization by Brucella abortus 2308 and its virulence in C57BL/6 mice. J Bacteriol 200:e00471-18. https://doi.org/10 .1128/JB.
Downloaded fromin vitro cultivation (5), but for others, this metal only appears to be required when the bacteria are subjected to an environmental stress, such as an exposure to reactive oxygen species (ROS) (6). Mn-dependent superoxide dismutases such as SodA, for instance, are important cytoplasmic antioxidants in bacteria (7), and in some cases, bacteria can substitute Mn for Fe in cellular proteins that do not require the redox activity of the latter metal for their function as a means of protecting these proteins from damage mediated by ROS via Fenton chemistry (6).Brucella strains produce a single high-affinity Mn transporter, MntH, and a phenotypic analysis of an isogenic mntH mutant derived from B. abortus 2308 indicates that Mn plays an important role in the basic physiology of these bacteria (8). The B. abortus mntH mutant, for instance, displays delayed growth compared to...
