Alkaline Phosphatase in Dictyostelium discoideum

Abstract

SUMMARYSeveral phosphatases have been demonstrated in Dictyostelium discoideum. The alkaline phosphatase, pH optimum 9.0, is a 5'-nucleotidase, attacking adenosine monophosphate and deoxyadenosine monophosphate, but catalyses also hydrolysis of p-nitrophenyl phosphate. In the absence of exogenous nutrients this enzyme increases about 6-fold in vitro during differentiation. Its activity\in vivo may in part be controlled through endproduct inhibition by orthophosphate which has been found to accumulate in the cells during sporulation. Exogenous orthophosphate and glucose repress the levels of alkaline phosphatase in the spores. The data support the conclusion that end product inhibition and repression collaborate to ensure maximal alkaline phosphatase activity in vivo during culmination. Exogenous adenosine and deoxyadenosine increase the alkaline phosphatase levels in the sorocarps.

The inhibition of Dictyostelium discoideum alkaline phosphatase by a low molecular weight factor and its implication for the developmental regulation of the enzyme

“…Several years ago, Gezelius and Wright reported differential instability of alkaline phosphatase extracted from vegetative amoebae, preculmination cells and sorocarps [9]. Enzyme from vegetative cells retained only ten percent of its activity when cell-free extracts were stored for X days at 4°C while from preculmination cells and sorocarp cells retained 29% and 50% of the initial activity respectively under identical conditions.…”

Partial Purification and Some Properties of Spore Germination Promoter(s) forDictyostelium discoideumExcreted byKlebsiella aerogenes

“…In this connection, it is noteworthy to recall that D. discoideum spores contain 65 mM inorganic phosphate. 7 ) We had analyzed and reported some of the chemical nature of the SGPs. 9 ) The data from these experiments also confirmed 'most of the characteristics of the SGPs such as heat stability and enzyme digestion.…”

Analysis of 5′ nucleotidase and alkaline phosphatase by gene disruption in Dictyostelium

“…The 5NT activity showed an alkaline pH optimum, and like ALP in other systems, was able to degrade the artificial substrate p-nitrophenyl phosphate (pNPP) (Gezelius and Wright, 1965). When the protein containing 5ЈAMP degrading activity was purified to homogeneity it was found that both 5ЈAMP and pNPP could be utilized as a substrate, but that the enzyme showed a high preference for 5ЈAMP over any other natural products.…”

“…In Dictyostelium a phosphatase activity exhibiting an alkaline pH optimum and a substrate preference for 5ЈAMP has been the subject of study by several laboratories (Armant and Rutherford, 1981;Weeks, 1985, 1989a,b;Cladaras et al, 1983;Das and Weeks, 1980Gezelius and Wright, 1965;Glomp et al, 1985;Krivanek, 1956;Loomis, 1969;MacLeod and Loomis, 1979;O'Day and Francis, 1973;Parish and Pelli, 1974;Tisa and Cotter, 1979). Assays of the phosphatase activity have utilized artificial substrates as well as 5ЈAMP.…”