Expression and role of the universal stress protein, UspA, of Escherichia coli during growth arrest

The synthesis of the small, cytoplasmic protein UspA universal stress protein A) of Escherichia coli is induced as soon as the cell growth rate falls below the maximal growth rate supported by the medium, regardless of the condition inhibiting growth. The increase in UspA synthesis appears to be the result of Induction of the monocistronic uspA gene. Induction of this gene during a heat-shock treatment is demonstrated to be the result of transcriptional activation of Σ 70 -dependent promoter which has previously been shown to be activated also during carbon starvation-induced growth arrest. Mutant cells lacking UspA grow at rates indistinguisible from the isogenic parent at different temperatures and in the presence of different growth inhibitors but are impaired in their ability to survive prolonged periods of complete growth inhibition caused by a variety of diverse stresses, including CdCl 2 , H 2 O 2 , DNP, CCCP exposure, and osmotic shock. Moreover, the uspA mutation results in an increased sensitivity of cells to carbon-source starvation (i.e. glucose, glycerol or succinate depletion). Also, the mutation causes a marked alteration in the timing of starvation protein expression but protein expression during steady-state growth appears to be normal. The results presented have prompted us to postulate that UspA may have a general protective function related to the growth arrest state.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73757/1/j.1365-2958.1994.tb00334.x.pd

Positive regulatory gene for temperature-controlled proteins in Escherichia coli

SummaryA group of nine proteins of Escherichia coli K12 vary in steady state level with growth temperature, and are particularly abundant above 40[deg]C. The identities of most of these HTP (high temperature production) proteins are unknown; they are primarily recognizable on two-dimensional polyacrylamide gels by their very high rates of synthesis during the ten-minute period following a shift-up in temperature. This stimulation, as much as 20-fold for some HTP proteins, is abolished by a conditionally lethal nonsense mutation in a chromosomal gene located at 75 minutes. Evidence suggests that this regulatory gene, htpR, makes an activator protein that is required for heat induction of HTP proteins.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24372/1/0000641.pd

Identification of a conditionally essential heat shock protein in Escherichia coli

Protein D48.5 was recognized as a heat-inducible protein of Escherichia coli during the screening of a group of random, temperature-inducible Mud-Lac fusion mutants. Physiological and genetic analysis demonstrated that (i) the structural gene for this protein, designated htpI, is a member of the o32-dependent heat shock regulon, (ii) at 37[deg]C the synthesis of protein D48.5 is nearly constitutive, increasing slightly with growth rate in media of different composition, and (iii) this protein is essential for growth at high temperature.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31386/1/0000299.pd

Patterns of protein synthesis in E. coli: a catalog of the amount of 140 individual proteins at different growth rates

The amount of 140 individual proteins of E. coli B/r was measured during balanced growth in five different media. The abundance of each protein was determined from its absolute amount in 14C-glucose-minimal medium and a measurement of its relative amount at each growth rate using a double labeling technique. Separation of the proteins was carried out by two-dimensional gel electrophoresis.This catalog of proteins, combined with 50 additional ribosomal proteins already studied, comprises about 5% of the coding capacity of the genome, but accounts for two thirds of the cell's protein mass.The behavior of most of these proteins could be described by a relatively small number of patterns. 102 of the 140 proteins exhibited nearly linear variations with growth rate. The remaining 38 proteins exhibited levels which seemed to depend more on the chemical nature of the medium than on growth rate.Proteins, including the ribosomal proteins, that increase in amount with increasing growth rate account for 20% of total cell protein by weight during growth on acetate, 32% on glucose-minimal medium and 55% on glucose-rich medium. Proteins with invariant levels in the various media comprise about 4% of the cell's total protein.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22607/1/0000157.pd

Stress proteins in biology and medicine : Edited by R. Morimoto, A. Tissieres, and C. Georgopoulos. Cold Spring Harbor, New York: Cold Spring Harbor Laboratory Press. (1990). 450 pp. $97.00

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28305/1/0000059.pd