Ca2+ signaling in prokaryotes

Abstract

431In both higher and lower eukaryotes, Ca 2+ ions are common intracellular signaling messengers. Along with cyclic nucleotides, diacylglycerol, nitric oxide, signaling oligopeptides, and some other active mole cules and ions, Ca 2+ cations are involved in the regula tion of numerous processes in eukaryotic cells, such as cell cycle, nuclear division, nerve impulse conduction, muscle contraction, and others [1][2][3].In prokaryotes, the role of Ca 2+ in intracellular sig naling is considerably less studied. Only a few works have considered Ca 2+ ions as potential regulators of such cellular processes as ion transport, spore germi nation, heterocyst differentiation, gene expression, cell motility, adaptation to low or high temperatures, virulence, etc. [5][6][7][8][9][10]. For a long time, investigation of Ca 2+ signaling in microbial cells was hindered by methodological problems in determining intracellular calcium concentrations ([Ca 2+ ] i ), calcium contami nation, reagent toxicity, and difficulties in handling individual cells; these questions were discussed in [11][12][13]. However, the unique optical methods and other approaches to investigation of individual bacte rial cells developed in the 1990s, which made it possi ble to register the changes in Ca 2+ levels in microbial cytosol in response to various external stimuli [14][15][16], boosted the studies of the regulatory functions of Ca 2+ in prokaryotic signaling.In the present review, we discuss the historical development of ideas concerning Ca 2+ signaling in prokaryotic cells and the current concepts of the related research in evolutionary biology. FUNCTIONS OF Ca 2+ IN PROKARYTIC CELLSThe first studies concerning the role of Ca 2+ as a secondary messenger in prokaryotic organisms date back to the 1970s, when Ordal found that decreased Ca 2+ intake by bacterial cells affected the chemotactic behavior in Bacillus subtilis [17]. Further research confirmed his observations in other microorganisms. A study on Escherichia coli showed that a decrease in [Ca 2+ ] i could alter the swimming mode in flagellate bacteria. Specifically, the characteristic slow and directed swimming changed to chaotic disordered motion [18]. Measurements of [Ca 2+ ] i levels in E. coli performed using the Fura 2 fluorescent Ca 2+ indicator revealed that bacterial repellents caused a temporary increase in [Ca 2+ ] i (to over 100 nM) and inhibited chemotaxis, whereas attractants, in contrast, tempo rarily decreased [Ca 2+ ] i levels and stimulated chemot axis [18].Experiments on blocking the voltage gated Ca 2+ channels (Cav) of different types (L, P/Q, and R) showed that inhibitors added to the incubation medium impaired the chemotactic behavior of bacte ria. In prokaryotes, it was expected that the stimuli inducing chemotactic reactions may increase the intake of extracellular Ca 2+ through the ion channels opened in response to membrane depolarization, as it occurs in protists and even in multicellular eukaryotes. However, there was no direct correlation between the extracellular...

Ion and pH Sensitivity of a TMBIM Ca2+ Channel

“…Nevertheless, intracellular Ca 2+ is key to bacterial chemotaxis, mobility, virulence, and adaptation to the environment (Dominguez et al, 2015). Although there are no intracellular Ca 2+ stores in bacteria, several components of the Ca 2+ signaling toolkits are expressed, including Ca 2+ -binding proteins and Ca 2+ -transport systems, such as P-type ATPases and electrochemical potential-driven transporters and channels (Dominguez, 2004;Shemarova and Nesterov, 2014;Dominguez et al, 2015). While basal cytosolic [Ca 2+ ] in prokaryotes is kept low in the 100 to 300 nM range, cytosolic [Ca 2+ ] can transiently rise in responses to nitrogen starvation, environmental stress, and production of metabolites (Dominguez et al, 2015).…”

Evidence of human‐like Ca2+ channels and effects of Ca2+ channel blockers in Acanthamoeba castellanii

“…Prokaryotes and microbes as primitive as algae are known to express a wide range of ion channels in their cellular membranes including Cav (Shemarova & Nesterov, ). As there are diverse types of calcium channels that are vital to the survival of microbes, selective antagonism of a specific type of Cav expressed by the microbe could prove as an alternative to conventionally used antibiotics in order to combat drug‐resistant infections.…”

Calcium binding to a disordered domain of a type III-secreted protein from a coral pathogen promotes secondary structure formation and catalytic activity

“…The regulation of protein function by Ca 2+ -dependent structural transitions provides a ubiquitous mechanism for cellular signaling networks in all kingdoms of life 1–3 . The rise of intracellular calcium levels is also a typical response in both pathogenic and mutually beneficial plant/microbe interactions 4 .…”