Department of Environmental Protection, Estación Experimental del Zaidín, CSIC, Granada, Spain.
J Bacteriol. 2012 Dec;194(24):6782-9. doi: 10.1128/JB.01094-12. Epub 2012 Oct 5.
LapF is a large secreted protein involved in microcolony formation and biofilm maturation in Pseudomonas putida. Its C-terminal domain shows the characteristics of proteins secreted through a type I secretion system and includes a predicted calcium binding motif. We provide experimental evidence of specific binding of Ca(2+) to the purified C-terminal domain of LapF (CLapF). Calcium promotes the formation of large aggregates, which disappear in the presence of the calcium chelator EGTA. Immunolocalization of LapF also shows the tendency of this protein to accumulate in vivo in certain extracellular regions. These findings, along with results showing that calcium influences biofilm formation, lead us to propose a model in which P. putida cells interact with each other via LapF in a calcium-dependent manner during the development of biofilms.
LapF 是一种大型分泌蛋白，参与假单胞菌属中微菌落的形成和生物膜的成熟。其 C 端结构域具有通过 I 型分泌系统分泌的蛋白的特征，包括一个预测的钙结合基序。我们提供了 LapF（CLapF）的纯化 C 端结构域与 Ca(2+)特异性结合的实验证据。钙促进大聚集体的形成，而在钙螯合剂 EGTA 存在的情况下，这些聚集体会消失。LapF 的免疫定位也表明，该蛋白在体内倾向于在某些细胞外区域积累。这些发现，以及钙影响生物膜形成的结果，使我们提出了一个模型，即假单胞菌属细胞在生物膜形成过程中通过 LapF 以钙依赖性的方式相互作用。
