Fig. 1.

Y. pestis Hms-dependent biofilm model. Chains of circles represent linked monomers of the EPS component of the biofilm (filled and unfilled circles, acetylated and deacetylated monomers). Labels indicate the putative or proven enzymic activities/functions of Hms proteins. The ‘+’ sign indicates likely stimulation of HmsR enzymatic activity by c-di-GMP. At 26–34 °C, all Hms proteins are highly expressed, while at 37 °C, the levels of HmsH, HmsR and HmsT are significantly reduced to varying degrees by post-translational mechanisms. HmsT degradation reduces c-di-GMP levels. This, along with low levels of HmsR and HmsH, inhibits biofilm formation.