PMID:21398480

Citation	Ruan, L, Pleitner, A, Gänzle, MG and McMullen, LM (2011) Solute transport proteins and the outer membrane protein NmpC contribute to heat resistance of Escherichia coli AW1.7. Appl. Environ. Microbiol. 77:2961-7
Abstract	This study aimed to elucidate determinants of heat resistance in Escherichia coli by comparing the composition of membrane lipids, as well as gene expression, in heat-resistant E. coli AW1.7 and heat-sensitive E. coli GGG10 with or without heat shock. The survival of E. coli AW1.7 at late exponential phase was 100-fold higher than that of E. coli GGG10 after incubation at 60°C for 15 min. The cytoplasmic membrane of E. coli AW1.7 contained a higher proportion of saturated and cyclopropane fatty acids than that of E. coli GGG10. Microarray hybridization of cDNA libraries obtained from exponentially growing or heat-shocked cultures was performed to compare gene expression in these two strains. Expression of selected genes from different functional groups was quantified by quantitative PCR. DnaK and 30S and 50S ribosomal subunits were overexpressed in E. coli GGG10 relative to E. coli AW1.7 upon heat shock at 50°C, indicating improved ribosome stability. The outer membrane porin NmpC and several transport proteins were overexpressed in exponentially growing E. coli AW1.7. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of membrane properties confirmed that NmpC is present in the outer membrane of E. coli AW1.7 but not in that of E. coli GGG10. Expression of NmpC in E. coli GGG10 increased survival at 60°C 50- to 1,000-fold. In conclusion, the outer membrane porin NmpC contributes to heat resistance in E. coli AW1.7, but the heat resistance of this strain is dependent on additional factors, which likely include the composition of membrane lipids, as well as solute transport proteins.
Links	PubMed PMC3126406 Online version:10.1128/AEM.01930-10
Keywords	Carrier Proteins/metabolism; Cell Membrane/chemistry; Escherichia coli/physiology; Escherichia coli/radiation effects; Escherichia coli Proteins/metabolism; Gene Expression Profiling; Heat-Shock Response; Hot Temperature; Membrane Lipids/analysis; Microarray Analysis; Microbial Viability/radiation effects; Porins/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ECOLI:NMPC		GO:0015288: porin activity	ECO:0000314:		F		Fig 3 E.coli cells expressing nmpC were more reistant to heat and had a higher survival rate.	complete CACAO 4522

References

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