New type of bacterial protection found within cells

Nov 13, 2012

UC Irvine biologists have discovered that fats within cells store a class of proteins with potent antibacterial activity, revealing a previously unknown type of immune system response that targets and kills bacterial infections.

Steven Gross, UCI professor of developmental & cell biology, and colleagues identified this novel intercellular role of histone proteins in fruit flies, and it could herald a new approach to fighting bacterial growth within cells. The study appears today in eLife, a new peer-reviewed, open-access journal supported by the Howard Hughes Medical Institute, the Max Planck Society and the Wellcome Trust.

"We found that these histone proteins have pan-antibacterial abilities and can have a wide-ranging effect," Gross said. "If we can discover how to manipulate the system to increase histone levels, we may one day have a new way to treat patients with bad bacterial infections."

Histones exist in large numbers in most animal cells; their primary job is to help DNA strands fold into compact and robust structures inside the nucleus. Gross said there is some evidence that histones secreted from cells protect against bacteria living outside cells. However, many bacteria enter cells, where they can avoid the immune system and continue replicating.

In principle, Gross said, histones could protect cells against such bacteria from the inside, but for many years this was thought unlikely because most histones are bound to DNA strands in the cell nucleus, whereas bacteria multiply in the cellular fluid outside the nucleus, called cytosol. Additionally, free histones can be extremely damaging to cells, so most species have developed mechanisms to detect and degrade free histones in the cytosol.

In their study, Gross and colleagues demonstrate that histones bound to lipid () droplets can protect cells against bacteria without causing any of the harm normally associated with the presence of free histones. In experiments with lipid droplets purified from Drosophila fruit fly embryos, they show that lipid-bound histones can be released to kill bacteria.

The researchers injected similar numbers of bacteria into Drosophila embryos that contained lipid-bound histones and into embryos genetically modified to not contain them. They discovered that the histone-deficient flies were 14 times more likely to die of bacterial infections. Similar results were found in experiments on adult flies. Additional evidence suggested that histones might also protect mice against .

"Because numerous studies have now identified histones on lipid droplets in many different – from humans as well as mice and flies – it seems likely that this system may be quite general," Gross said.

Explore further: Friction harnessed by proteins helps organize cell division

More information: Anand et al. eLife 2012;1:e00003. DOI: 10.7554/eLife.00003

add to favorites email to friend print save as pdf

Related Stories

Roles of DNA packaging protein revealed

Feb 12, 2009

Scientists at Albert Einstein College of Medicine of Yeshiva University have found that a class of chromatin proteins is crucial for maintaining the structure and function of chromosomes and the normal development ...

Researchers provide atomic view of a histone chaperone

Mar 01, 2012

Mayo Clinic researchers have gained insights into the function of a member of a family of specialized proteins called histone chaperones. Using nuclear magnetic resonance (NMR) spectroscopy and X-ray crystallography, they ...

Recommended for you

For cells, internal stress leads to unique shapes

1 hour ago

From far away, the top of a leaf looks like one seamless surface; however, up close, that smooth exterior is actually made up of a patchwork of cells in a variety of shapes and sizes. Interested in how these ...

Adventurous bacteria

2 hours ago

To reproduce or to conquer the world? Surprisingly, bacteria also face this problem. Theoretical biophysicists at Ludwig-Maximilians-Universitaet (LMU) in Munich have now shown how these organisms should ...

Revealing camouflaged bacteria

5 hours ago

A research team at the Biozentrum of the University of Basel has discovered an protein family that plays a central role in the fight against the bacterial pathogen Salmonella within the cells. The so cal ...

User comments : 0

More news stories

Chimpanzees prefer firm, stable beds

Chimpanzees may select a certain type of wood, Ugandan Ironwood, over other options for its firm, stable, and resilient properties to make their bed, according to a study published April 16, 2014 in the open-access ...

For cells, internal stress leads to unique shapes

From far away, the top of a leaf looks like one seamless surface; however, up close, that smooth exterior is actually made up of a patchwork of cells in a variety of shapes and sizes. Interested in how these ...

Down's chromosome cause genome-wide disruption

The extra copy of Chromosome 21 that causes Down's syndrome throws a spanner into the workings of all the other chromosomes as well, said a study published Wednesday that surprised its authors.

IBM posts lower 1Q earnings amid hardware slump

IBM's first-quarter earnings fell and revenue came in below Wall Street's expectations amid an ongoing decline in its hardware business, one that was exasperated by weaker demand in China and emerging markets.