PLEIOTROPIC CHANGES RESULTING FROM DEPLETION OF ERA, AN ESSENTIAL GTP-BINDING PROTEIN IN ESCHERICHIA-COLI

Phenotypic analysis of a temperature-sensitive era mutant strain indicates that Escherichia coli cells depleted of Era undergo many physiological changes. At 43-degrees-C, a completely non-permissive temperature, growth is arrested because of loss of the gene and depletion of the Era protein. Depletion of Era at 43-degrees-C results in depressed synthesis of heat-shock proteins DnaK, GroEL/ES, D33.4 and C62.5, lack of thermal induction of ppGpp pool levels, and increased capacity for carbon source metabolism through the citric acid cycle. Thus, in addition to inhibition of cell growth and viability, loss of Era function results in pleiotropic changes including abnormal adaptation to thermal stress.