OmpC and OmpF are required for growth under hyperosmotic stress above pH 8 in Escherichia coli

Kaeriyama, Masahide; Machida, Kazuhiro; Kitakaze, A.; Wang, H.; Lao, Qizong; Fukamachi, Toshihiko; Saito, Hiromi; Kobayashi, Hiroshi

doi:10.1111/j.1472-765x.2006.01845.x

Cited by 29 publications

(21 citation statements)

References 25 publications

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“…Porins are encoded by osmoresponsive genes in E. coli, are upregulated under osmotic stress, and contribute to the accumulation of high intracellular levels of compatible solutes (34). OmpC and OmpF are required for growth under hyperosmotic stress above pH 8 in E. coli (26). E. coli GGG10 harboring pYFP-nmpC exhibited substantially improved survival at 60°C.…”

Section: Discussionmentioning

confidence: 99%

Solute Transport Proteins and the Outer Membrane Protein NmpC Contribute to Heat Resistance of Escherichia coli AW1.7

Ruan

Pleitner

Gänzle

et al. 2011

Appl Environ Microbiol

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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.Escherichia coli is a common contaminant of the food supply. The majority of the strains of this species are not pathogenic; however, their relatively high resistance to environmental insults and the occurrence of virotypes with a low infectious dose, particularly enterohemorrhagic E. coli, make E. coli an organism of major concern in the production of minimally processed foods, particularly produce and fresh beef (11).Most strains of E. coli have a D 60 value (the duration of heat treatment at 60°C required to reduce the number of microorganisms to 1/10 of the initial value) of less than 1 min. However, the heat resistance of E. coli is highly variable among different strains and individual strains exhibit D 60 values of up to 6.5 min (8,21,25,37). The heat resistance of individual strains of E. coli relates to their ability adapt to heat stress by the homoviscous adaptation of the plasma membrane, as well as the synthesis of heat shock proteins (20, 43). The 32 -induced expression of heat shock proteins after sublethal thermal stress increases resistance to lethal heat treatment (43; for a review, see reference 6). Increased basal expression of the heat shock proteins DnaK, Lon, and ClpX was linked to the increased heat resistance of E. coli mutants LMM1010, LMM1020, and LMM 1030 (1, 21). The S -mediated general stress response additionally contributes to acid, heat, pressure, and salt resistance in E. coli (2,14,22,3...

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Section: Discussionmentioning

confidence: 99%

Solute Transport Proteins and the Outer Membrane Protein NmpC Contribute to Heat Resistance of Escherichia coli AW1.7

Ruan

Pleitner

Gänzle

et al. 2011

Appl Environ Microbiol

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“…Moreover, an ompR mutant is affected in the level of expression of many genes [Oshima et al, 2002]. Similarly, mutants in the ompC and ompF genes were also growthdeficient at high osmolarity and alkaline pH [Kaeriyama et al, 2006;Sato et al, 2000]. The ompA gene is repressed in acid pH [Huang et al, 2007].…”

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confidence: 99%

The Complexities of Porin Genetic Regulation

Cruz

Calva²

2010

Microb Physiol

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Our understanding of porin regulation has revealed not only increasing complexity in the regulatory mechanisms, but also that the porin repertoire is more extensive than previously conceived. Initially, the OmpR response regulator was described as the master regulator of porin genes, but many more regulators are involved such as CpxR, PhoB, Lrp, Rob, MarA, SoxS, CadC, CRP, Fnr, ToxR, H-NS, StpA, IHF, HU and LeuO. In addition to MicF, the first small RNA (sRNA) that was proposed to regulate porin expression, porins are post-transcriptionally regulated by a variety of other sRNAs, namely, MicC, MicA, IpeX, RseX, InvR, CyaR and RybB. Future challenges include the full integration of all the regulatory circuitries. Whether quiescent porins are merely replacements of the major porins or are part of novel metabolic programs has yet to be elucidated. The comprehensive exploration of the environmental determinants that affect porin gene expression should yield valuable new information about the functions of these important proteins.

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“…For many bacteria in the natural environment, growth is limited by the availability of nutrients. Uptake of nutrients occurs via protein channels known as porins in the OM of gram-negative bacteria (20), and the transcription of specific porin genes increases under nutrient starvation (21) and in response to, for example, phosphate starvation (27) and osmotic stress (18). An increase in the number of porin molecules in the OM is therefore an important response to nutrient limitation, and so any increase in the surface area of the OM, with a concomitant increase in porins, may be beneficial.…”

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confidence: 99%

Nanoscale Visualization of a Fibrillar Array in the Cell Wall of Filamentous Cyanobacteria and Its Implications for Gliding Motility

Read¹,

Connell

Adams³

2007

J Bacteriol

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Many filamentous cyanobacteria are motile by gliding, which requires attachment to a surface. There are two main theories to explain the mechanism of gliding. According to the first, the filament is pushed forward by small waves that pass along the cell surface. In the second, gliding is powered by the extrusion of slime through pores surrounding each cell septum. We have previously shown that the cell walls of several motile cyanobacteria possess an array of parallel fibrils between the peptidoglycan and the outer membrane and have speculated that the function of this array may be to generate surface waves to power gliding. Here, we report on a study of the cell surface topography of two morphologically different filamentous cyanobacteria, using field emission gun scanning electron microscopy (FEGSEM) and atomic force microscopy (AFM). FEGSEM and AFM images of Oscillatoria sp. strain A2 confirmed the presence of an array of fibrils, visible as parallel corrugations on the cell surface. These corrugations were also visualized by AFM scanning of fully hydrated filaments under liquid; this has not been achieved before for filamentous bacteria. FEGSEM images of Nostoc punctiforme revealed a highly convoluted, not parallel, fibrillar array. We conclude that an array of parallel fibrils, beneath the outer membrane of Oscillatoria, may function in the generation of thrust in gliding motility. The array of convoluted fibrils in N. punctiforme may have an alternative function, perhaps connected with the increase in outer membrane surface area resulting from the presence of the fibrils.Cyanobacteria are phototrophic prokaryotes that vary in morphology from unicellular strains to filamentous forms capable of complex cellular differentiation (1, 2). Many cyanobacteria are motile. Some unicellular Synechococcus strains are capable of swimming by a mechanism that does not employ flagella (28) in which thrust is generated by an extracellular protein, SwmA (6, 19), but most motile cyanobacteria employ gliding, which requires attachment to a surface. The unicellular Synechocystis sp. strain PCC 6803 moves by a form of gliding often referred to as twitching motility, which is powered by type IV pili on the cell surface (4,5,30). In filamentous strains, in which forward movement is often accompanied by rotation of the filament about its long axis (10), the mechanism of gliding is unknown. Halfen and Castenholz proposed a model for gliding (11) based on the results of their own electron microscopy (EM) studies of motile filamentous cyanobacteria and on the theories of Jarosch (16). They speculated that the motor for gliding in the filamentous Oscillatoriaceae might be provided by proteinaceous contractile fibrils, 6 to 9 nm in diameter, located between the peptidoglycan layer and the outer membrane (OM) and that rotation of the filaments during gliding might be a result of the helical arrangement of the fibrils. An ultrastructural examination of the cell walls of four gliding filamentous cyanobacteria by Hoiczyk and Baumeister (12...

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OmpC and OmpF are required for growth under hyperosmotic stress above pH 8 in Escherichia coli

Cited by 29 publications

References 25 publications

Solute Transport Proteins and the Outer Membrane Protein NmpC Contribute to Heat Resistance of Escherichia coli AW1.7

Solute Transport Proteins and the Outer Membrane Protein NmpC Contribute to Heat Resistance of Escherichia coli AW1.7

The Complexities of Porin Genetic Regulation

Nanoscale Visualization of a Fibrillar Array in the Cell Wall of Filamentous Cyanobacteria and Its Implications for Gliding Motility

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