Holin, CidA (Bayles, 2003; Yang et al., 2005; Ranjit et al. 2011).  Functions in biofilm formation in part by mediating release of cytoplasmic DNA during cell lysis to contribute to the biofilm matrix (Ranjit et al. 2011; Fischer et al. 2013).  This protein contributes to cell lysis of dying cells (Patton et al. 2005).  Calcium-chelating alizarin and other anthraquinones inhibit biofilm formation and modulate the expression of the cid/lrg genes (encoding the holin/antiholin system) (Lee et al. 2016). CidA and LrgA function as holins to support endolysin-induced lysis, and the lrgAB operon also facilitates pyruvate uptake during microaerobic and anaerobic growth (Laabei and Duggan 2022). The Staphylococcus aureus CidA and LrgA proteins are functional holins involved in the transport of by-products of carbohydrate metabolism (Endres et al. 2022).