[An update of calcium signaling in bacteria--a review]

In eukaryotes, Ca2+ is an important second messenger and regulates diverse cellular activities ranging from muscle contraction to fertilization. In bacteria, growing evidence suggests that Ca2+ also plays important regulatory roles in various physiological processes. Here we review current understanding of calcium regulation in bacteria from the following aspects: 1) the concept of bacterial [Ca2+]i and its determination; 2) cellular processes affected by [Ca2+]i changes; 3) transportation of Ca2+ across bacterial membrane; 4)eukaryotic calcium binding proteins in bacteria and their functions.