Effect of amino acid deprivation and chloramphenicol treatment on cell sizes of rel+ and relA− strains of Escherichia coli

1978 ◽  
Vol 24 (6) ◽  
pp. 761-764 ◽  
Author(s):  
Edward E. Ishiguro ◽  
William D. Ramey
Keyword(s):  
Escherichia Coli ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Cell Size ◽  
Size Distributions ◽  
Amino Acid Deprivation ◽  
Cell Size Distributions ◽  
K 12 ◽  
Cell Envelopes ◽  
Derivatives Of

The effects of inhibition of protein synthesis on the cell size distributions of rel+ and relA− derivatives of Escherichia coli K-12 were determined. Amino acid deprivation resulted in a reduction in the cell sizes of rel+ strains but not of relA− strains. Treatment with chloramphenicol (CAM) did not alter the size distributions of either rel+ or relA− strains except when they were rel+dap−. CAM treatment of rel+dap− strains resulted in an increase in cell size. It is proposed that these results reflect differences in the structures of the cell envelopes of rel+ and relA− bacteria.

scholarly journals Point Mutations in Transmembrane Helices 2 and 3 of ExbB and TolQ Affect Their Activities in Escherichia coli K-12

2004 ◽  
Vol 186 (13) ◽  
pp. 4402-4406 ◽  
Author(s):  
Volkmar Braun ◽  
Christina Herrmann
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Transmembrane Helix ◽  
Point Mutations ◽  
Transmembrane Helices ◽  
The Third ◽  
Form Part ◽  
K 12

ABSTRACT Replacement of glutamate 176, the only charged amino acid in the third transmembrane helix of ExbB, with alanine (E176A) abolished ExbB activity in all determined ExbB-dependent functions of Escherichia coli. Combination of the mutations T148A in the second transmembrane helix and T181A in the third transmembrane helix, proposed to form part of a proton pathway through ExbB, also resulted in inactive ExbB. E176 and T148 are strictly conserved in ExbB and TolQ proteins, and T181 is almost strictly conserved in ExbB, TolQ, and MotA.

Effect of amino acid deprivation on initiation of protein synthesis in rat hepatocytes

1989 ◽  
Vol 256 (1) ◽  
pp. C18-C27 ◽  
Author(s):  
W. V. Everson ◽  
K. E. Flaim ◽  
D. M. Susco ◽  
S. R. Kimball ◽  
L. S. Jefferson
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Rat Hepatocytes ◽  
Initiation Factor ◽  
Synthetic Activity ◽  
Perfused Liver ◽  
Amino Acid Deprivation ◽  
Isolated Rat Hepatocytes ◽  
Reticulocyte Lysate

Conditions were defined for maintaining optimal protein synthetic activity in suspensions of freshly isolated rat hepatocytes. Under these conditions, isolated hepatocytes exhibited rates of protein synthesis and levels of polysomal aggregation equivalent to those observed in vivo and in perfused liver. Deprivation of total amino acids or single, essential amino acids resulted in a rapid decrease in the rate of protein synthesis, which was readily reversed by readdition of the deficient amino acid(s). The decrease was accompanied by a disaggregation of polysomes and an inhibition of 43S initiation complex formation, which was indicative of a limitation in the rate of initiation of protein synthesis. Extracts prepared from perfused liver deprived of amino acids were inhibitory to initiation of protein synthesis in reticulocyte lysate. The inhibition in reticulocyte lysate was accompanied by an increase in phosphorylation of the alpha-subunit of eukaryotic initiation factor 2 (eIF-2), suggesting activation of an eIF-2 alpha kinase or inhibition of a phosphatase in amino acid-deprived hepatocytes. This suggestion was confirmed by prelabeling hepatocytes with 32Pi before amino acid deprivation. Incorporation of 32Pi into eIF-2 alpha was two- to threefold higher in lysine-deprived cells than in hepatocytes incubated in fully supplemented medium. Overall, the results indicated that an increase in eIF-2 alpha phosphorylation was responsible for the defect in initiation of protein synthesis caused by amino acid deprivation.

scholarly journals MRI‐cytometry: Mapping nonparametric cell size distributions using diffusion MRI

2020 ◽  
Vol 85 (2) ◽  
pp. 748-761 ◽  
Author(s):  
Junzhong Xu ◽  
Xiaoyu Jiang ◽  
Sean P. Devan ◽  
Lori R. Arlinghaus ◽  
Eliot T. McKinley ◽  
...  
Keyword(s):  
Cell Size ◽  
Diffusion Mri ◽  
Size Distributions ◽  
Cell Size Distributions
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