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Targeting of proteins to different cellular compartments in E. coli. From MicrobeWiki, the student-edited microbiology resource Jump to: navigation, search Contents [hide]

   * 1 Introduction
   * 2 Section 1
   * 3 Section 2
   * 4 Section 3
   * 5 Conclusion
   * 6 References

Introduction

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Escherichia coli (E. coli)is an inhabitant of the human intestine and a model organism for gram-negative bacteria (http://en.wikipedia.org/wiki/Escherichia_coli). While it has been long assumed that prokaryotes lack the sophistical intracellular architecture of eukaryotic cells and are unorganized bags of cytoplasm surrounded by a membrane, more recent research has shown that prokaryotes do indeed have cytoplasmic organization with the nucleoid and various proteins restricted to certain areas. A fundamental issue for cells is how to target protein to their correct cellular location. In gram-negative bacteria proteins may need to be selectively localized to the inner membrane, outer membrane, periplasm or secreted outside the cell (Figure 1). Proteins that fail to reach their correct localization will not function appropriately. For example, the Lac Y gene product, lactose permease, must be present in the inner membrane to allow lactose entry into the cytoplasm.

Figure 1.A schematic diagram of compartments in E. coli.
Figure 1.A schematic diagram of compartments in E. coli. From Pugsley 57 (1) 50 1993 Microbiology and Molecular Biology Reviews. http://mmbr.asm.org/cgi/reprint/57/1/50

File:EscherichiaColi NIAID.jpg

Figure 1.A schematic diagram of compartments in E. coli. From Pugsley 57 (1) 50 1993 Microbiology and Molecular Biology Reviews. http://mmbr.asm.org/cgi/reprint/57/1/50

File:EscherichiaColi NIAID.jpg

[x 400px|right|A schematic diagram of compartments in E. coli. From Current Opinion in Biotechnology, ] Other examples: Bold Italic Subscript: H2O Superscript: Fe3+


Introduce the topic of your paper. What microorganisms are of interest? Habitat? Applications for medicine and/or environment?

Inner Membrane

Include some current research, with at least one figure showing data.

Periplasm

Include some current research, with at least one figure showing data.

Outer membrane

Include some current research, with at least one figure showing data. Conclusion

Extracellular

In addition to targeting to various cellular locations, some proteins are destined to leave the cell entirely and enter the extracellular environment. Examples include hemolysins (http://en.wikipedia.org/wiki/Hemolysin ) exotoxins that l yse host cells to release nutrients and pili that mediate attachment to substrates. In gram-negative cells secreted proteins must cross both the inner and outer membranes. Secretion across the outer membranes differs from secretion across the inner membrane in a number of respects. In contrast to the IM Sec proteins through which proteins pass in an unfolded state, proteins may partially fold in the periplasm prior to secretion through the OM. In addition any OM transporters lack access to cytoplasmic ATP so different energy sources must be used. Thanassim and Hultgren (2000) have reviewed the different pathways proteins may take on their voyage outside the Gram-negative cell. They discuss

Overall text length at least 3,000 words, with at least 3 figures.

References

Cornelis, P. Current opinion in biotechnology 2000;11(5):450-4. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VRV-41BV2FD-8&_user=7774802&_coverDate=10%2F01%2F2000&_rdoc=1&_fmt=high&_orig=gateway&_origin=gateway&_sort=d&_docanchor=&view=c&_searchStrId=1665295606&_rerunOrigin=google&_acct=C000062877&_version=1&_urlVersion=0&_userid=7774802&md5=1b0d9c4e9467114f398efccfe82636d5&searchtype=a

Edited by student of Joan Slonczewski for BIOL 238 Microbiology, 2010, Kenyon College. Retrieved from "http://microbewiki.kenyon.edu/index.php/BIOL_238_Paper_2010" Category: Pages edited by students of Joan Slonczewski at Kenyon College