Isolation and characterization of mutations affecting UDPG pyrophosphorylase activity in Dictyostelium discoideum

A procedure for screening large numbers of clones for an enzyme activity was used to isolate mutations which affect UDPG pyrophosphorylase activity (EC 2.7.7.9) in the cellular slime mold Dictyostelium discoideum. Five strains were recovered which have little or no UDPG pyrophosphorylase activity. Ten other strains were found which have significant activity in vivo which is rapidly inactivated upon cell lysis. These strains have permitted us to evaluate the role of UDPG pyrophosphorylase during growth and development. The enzyme affects the growth rate of the cells but is not essential for growth. However, during development the lack of enzyme activity leads to cell death and lysis. Strains which lack UDPG pyrophosphorylase accomplish early developmental events but are unable to culminate. However, certain biochemical and cytological differentiations associated with late stages were observed.