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Chemotactic and osmotic signals share a cGMP transduction pathway in Dictyostelium discoideum
Author(s) -
Kuwayama Hidekazu,
Van Haastert Peter J.M
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)00183-5
Subject(s) - chemotaxis , dictyostelium discoideum , microbiology and biotechnology , osmotic shock , signal transduction , biology , dictyostelium , mutant , myosin light chain kinase , intracellular , phosphorylation , biochemistry , receptor , gene
In the ameboid eukaryote Dictyostelium discoideum , chemotactic stimulation by cAMP induces an increase of intracellular cGMP and subsequently the phosphorylation of myosin heavy chain II. Resistance to high osmotic stress also requires transient increases of intracellular cGMP and phosphorylation of myosin heavy chain II, although the kinetics is much slower than for chemotaxis. To examine if chemotaxis and osmotic stress share common signaling components we systematically analyzed the osmotic cGMP response and survival in chemotactic mutants with altered cGMP signaling. Null mutants with deletions of cell surface cAMP receptors or the associated GTP‐binding proteins G α 2 and G β show no cAMP‐induced cGMP response and chemotaxis; in contrast, osmotic stress induces the normal cGMP accumulation and survival. The same result was obtained with the non‐chemotactic mutant KI‐10, which lacks the activation of guanylyl cyclase by cAMP. This indicates that these components are required for chemotaxis but not osmotic cGMP signaling and survival. The potential guanylyl cyclase null mutant KI‐8 shows no chemotaxis, no osmotic cGMP increase and reduced survival in high osmolarity. Two types of cGMP‐binding protein mutants, KI‐4 and KI‐7, also show reduced tolerance during high osmotic stress. Taken together, these observations clarify that chemotactic and osmotic signals are detected by different mechanisms, but share a cGMP signaling pathway.