scholarly journals Genetic and physiological tests of three phosphate-specific transport mutants of Escherichia coli.

1981 ◽  
Vol 145 (3) ◽  
pp. 1249-1256 ◽  
Author(s):  
G Zuckier ◽  
A Torriani
Keyword(s):  
Escherichia Coli ◽  
Specific Transport ◽  
Transport Mutants ◽  
Physiological Tests

scholarly journals Elucidation of a PTS–Carbohydrate Chemotactic Signal Pathway inEscherichia coliUsing a Time-resolved Behavioral Assay

1999 ◽  
Vol 10 (4) ◽  
pp. 1133-1146 ◽  
Author(s):  
Renate Lux ◽  
V. Ranjit N. Munasinghe ◽  
Fred Castellano ◽  
Joseph W. Lengeler ◽  
John E. T. Corrie ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Response Regulator ◽  
High Sensitivity ◽  
Signal Pathway ◽  
Response Threshold ◽  
Computer Assisted ◽  
Time Resolved ◽  
Response Range ◽  
Transport Mutants ◽  
Signaling Activity

Chemotaxis of Escherichia coli toward phosphotransferase systems (PTSs)–carbohydrates requires phosphoenolpyruvate-dependent PTSs as well as the chemotaxis response regulator CheY and its kinase, CheA. Responses initiated by flash photorelease of a PTS substrates d-glucose and its nonmetabolizable analog methyl α-d-glucopyranoside were measured with 33-ms time resolution using computer-assisted motion analysis. This, together with chemotactic mutants, has allowed us to map out and characterize the PTS chemotactic signal pathway. The responses were absent in mutants lacking the general PTS enzymes EI or HPr, elevated in PTS transport mutants, retarded in mutants lacking CheZ, a catalyst of CheY autodephosphorylation, and severely reduced in mutants with impaired methyl-accepting chemotaxis protein (MCP) signaling activity. Response kinetics were comparable to those triggered by MCP attractant ligands over most of the response range, the most rapid being 11.7 ± 3.1 s−1. The response threshold was <10 nM for glucose. Responses to methyl α-d-glucopyranoside had a higher threshold, commensurate with a lower PTS affinity, but were otherwise kinetically indistinguishable. These facts provide evidence for a single pathway in which the PTS chemotactic signal is relayed rapidly to MCP–CheW–CheA signaling complexes that effect subsequent amplification and slower CheY dephosphorylation. The high sensitivity indicates that this signal is generated by transport-induced dephosphorylation of the PTS rather than phosphoenolpyruvate consumption.

A new locus in the phosphate specific transport (PST) region of Escherichia coli

1984 ◽  
Vol 197 (1) ◽  
pp. 98-103 ◽  
Author(s):  
Ruth Levitz ◽  
Avihou Klar ◽  
Nehemia Sar ◽  
Ezra Yagil
Keyword(s):  
Escherichia Coli ◽  
Specific Transport

Genes encoding osmoregulatory proline/glycine betaine transporters and the proline catabolic system are present and expressed in diverse clinical Escherichia coli isolates

1994 ◽  
Vol 40 (5) ◽  
pp. 397-402 ◽  
Author(s):  
Doreen E. Culham ◽  
Katherine S. Emmerson ◽  
Bonnie Lasby ◽  
Daniel Mamelak ◽  
Brian A. Steer ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Dna Sequences ◽  
Glycine Betaine ◽  
Clinical Isolates ◽  
E Coli ◽  
High Osmolality ◽  
Proline Catabolism ◽  
K 12 ◽  
Physiological Tests

Sixty-three clinical isolates identified as Escherichia coli, 30 from the human urinary tract and 33 derived from other human origins, were screened for proline/glycine betaine transporters similar to those that support proline catabolism and proline- or glycine betaine-based osmoregulation in E. coli K-12. Both molecular (DNA- and protein-based) analyses and physiological tests were performed. All tests were calibrated with E. coli K-12 derivatives from which genetic loci putP (encoding a proline transporter required for proline catabolism), proP, and (or) proU (loci encoding osmoregulatory proline/glycine betaine transporters) had been deleted. All clinical isolates showed both enhanced sensitivity to the toxic proline analogue azetidine-2-carboxylate on media of high osmolality and growth stimulation by glycine betaine in an artificial urine preparation of high osmolality. DNA sequences similar to the putP, proP, and proU loci of E. coli K-12 were detected by DNA amplification and (or) hybridization and protein specifically reactive with antibodies raised against the ProX protein of E. coli K-12 (a ProU constituent) was detected by western blotting in over 95% of the isolates. Two anomalous isolates were reclassified as non-E. coli on the basis of the API 20E series of tests. A protein immunochemically cross-reactive with the ProP protein of E. coli K-12 was also expressed by the clinical isolates. Since all three transporters were ubiquitous, no particular correlation between clinical origin and PutP, ProP, or ProU activity was observed. These data suggest that the transporters encoded in loci putP, proP, and proU perform housekeeping functions essential for the survival of E. coli cells in diverse habitats.Key words: osmoregulation, betaine transport, urinary tract infection, Escherichia coli.

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