Figure 2. Carbohydrate uptake and metabolism by Y. pestis in its mammalian host.

Genes encoding transporters for fructose (FruAB), mannose (ManZYX), maltose (MalEMGKF and MalE₂FG), glucose (PtsG), gluconate (GntM) and fructuronate (GntP) and the carbohydrate metabolism genes shown in red or purple were all overexpressed in vivo [7]. In virulence tests, mutants lacking a gene highlighted in red were virulence-attenuated, whereas those lacking a gene highlighted in purple were not. Genes in grey were not upregulated in vivo and their role in virulence has yet to be elucidated; hence, the importance of the metabolic fluxes involving the corresponding enzymes in virulence is unknown (grey arrows). Red and purple arrows respectively indicate the metabolic fluxes considered to be important and non-essential for virulence. Yellow arrowheads represent the metabolic pathways that glucose and gluconate might follow.