Navigation Links
Biological wires carry electricity thanks to special amino acids
Date:3/11/2013

Slender bacterial nanowires require certain key amino acids in order to conduct electricity, according to a study to be published in mBio, the online open-access journal of the American Society for Microbiology, on Tuesday, March 12.

In nature, the bacterium Geobacter sulfurreducens uses these nanowires, called pili, to transport electrons to remote iron particles or other microbes, but the benefits of these wires can also be harnessed by humans for use in fuel cells or bioelectronics. The study in mBio reveals that a core of aromatic amino acids are required to turn these hair-like appendages into functioning electron-carrying biological wires.

"It's the aromatic amino acids that make it a wire," says lead author Derek Lovley of the University of Massachusetts, Amherst. Lovley and his colleagues removed the pivotal amino acids from the pili and replaced them with smaller, non-aromatic amino acids. Without these key components, Lovley says, the pili are nothing more than protein strings. "We showed it's not good enough to just make the string - you've got to make a wire," says Lovley.

G. sulfurreducens "breathes" by removing electrons from organic materials and funneling them to iron oxides or to other microorganisms, much the way humans pull electrons out of organic molecules in food and dump them on oxygen. The bacteria use their pili to reach out to iron oxides or other microbes, transferring the "waste" electrons along the structure to the destination. Geobacter's pili are only 3-5 nanometers wide, but they can be 20 micrometers long, many times longer than the cell itself.

Trafficking in electrons is how all living things breathe, but it is normally carried out by discrete proteins or other molecules that act like containers for shuttling electrons from one place to another. Lovley says earlier results showed the pili in G. sulfurreducens possess metallic-like conductivity, the ability to carry electrons along a continuous structure, a controversial finding in biology.

To investigate how pili accomplish this singular feat, Lovley says they looked to non-biological organic materials that can conduct electricity. "In those synthetic materials, it's aromatic compounds that are responsible for the conductivity. We hypothesized that maybe it's similar in the Geobacter pili. In this case, it would be aromatic amino acids." Aromatic compounds have a highly stable ring-shaped structure made of carbon atoms.

Turning to the pili, Lovley says his group looked for aromatic amino acids in the parts of the pili proteins that would most likely contribute to the conductivity. Using genetic techniques, they developed a strain of Geobacter that makes pili that lack aromatic amino acids in these key regions, then they tested whether these pili could still conduct electricity. They could not. Removing the aromatic amino acids was a bit like taking the copper out of a plastic-covered electrical wire: no copper means no current, and all you're left with is a string.

Removing aromatic amino acids from the pili prevents the bacteria from reducing iron, too, says Lovley, an important point because it adds further proof that Geobacter uses its pili as nanowires for carrying electrons to support respiration.

Metal reducers like Geobacter show a lot of promise for use in fuel cells, says Lovley, and by feeding electrons to the microbes that produce the methane, they're an important component of anaerobic digesters that produce methane gas from waste products. Understanding how they shuttle their electrons around and how to optimize the way the pili function could lead to better technologies.

Moving forward, Lovley says his own lab plans to explore the possibilities of biological nanowires, exploring how to make them more or less conductive.


'/>"/>

Contact: Jim Sliwa
jsliwa@asmusa.org
202-942-9297
American Society for Microbiology
Source:Eurekalert

Related biology news :

1. Wayne State University researchers techniques enable more, faster testing of biological liquids
2. Snooze button on biological clocks improves cell adaptability
3. Advance promises to expand biological control of crop pests
4. Visualizing biological networks in 4-D
5. Cornell engineers solve a biological mystery and boost artificial intelligence
6. The neurobiological consequence of predating or grazing
7. UTSA engineer Hai-Chao Han named Fellow of Medical and Biological Engineering Institute
8. A nanoscale window to the biological world
9. Synthetic and biological nanoparticles combined to produce new metamaterials
10. New book details the biological and cultural diversity of Khawa Karpo, sacred mountain of Tibet
11. Developing second skin military fabric to repel chemical and biological agents
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:4/6/2017)... Forecasts by Product Type (EAC), Biometrics, Card-Based ... & Logistics, Government & Public Sector, Utilities / Energy ... Nuclear Power), Industrial, Retail, Business Organisation (BFSI), Hospitality & ... for a definitive report on the $27.9bn Access Control ... ...
(Date:4/3/2017)... , April 3, 2017  Data captured ... engineering platform, detected a statistically significant association ... prior to treatment and objective response of ... potential to predict whether cancer patients will ... treatment, as well as to improve both pre-infusion ...
(Date:3/28/2017)... India , March 28, 2017 ... IP, Biometrics), Hardware (Camera, Monitors, Servers, Storage Devices), Software ... Vertical, and Region - Global Forecast to 2022", published ... Billion in 2016 and is projected to reach USD ... between 2017 and 2022. The base year considered for ...
Breaking Biology News(10 mins):
(Date:10/10/2017)... ... October 10, 2017 , ... ... targeted antibody-drug conjugate (ADC) therapeutics, today confirmed licensing rights that give it ... Nanoparticle), a technology developed in collaboration with Children’s Hospital Los Angeles (CHLA). ...
(Date:10/10/2017)... -- International research firm Parks Associates announced today that ... TMA 2017 Annual Meeting , October 11 in Scottsdale, Arizona ... market and how smart safety and security products impact the competitive landscape. ... Parks Associates: Smart Home Devices: Main Purchase ... "The residential security market has experienced continued growth, ...
(Date:10/10/2017)... PA (PRWEB) , ... October 10, 2017 , ... ... year’s recipients of 13 prestigious awards honoring scientists who have ... presented in a scheduled symposium during Pittcon 2018, the world’s leading conference and ...
(Date:10/9/2017)... ... October 09, 2017 , ... At its national board meeting in North ... in Harvard University’s Departments of Physics and Astronomy, has been selected for membership in ... winning team for the 2015 Breakthrough Prize in Fundamental physics for the discovery of ...
Breaking Biology Technology: