Study reveals enzyme that behaves like a 'quantum inchworm'

May 16, 2000

Little is known about the actions of the tiny, critically important machines that maintain DNA, the chemical code coiled inside all living cells. Now UC Davis researchers have peered under the hood of one such machine to reveal new details about the workings of these essential housekeepers.

RecBC is an enzyme that works inside the E. coli bacterium. This nanomachine, one one-billionth of a meter in size, is a molecular motor. It moves along DNA, separating the two sides of the ladder-shaped DNA so that its rungs can be repaired, their code can be read or they can be paired with another DNA partner.

Most DNA investigators expected that RecBC would move along one to five rungs, or nucleotides, at a time -- a respectable step size for enzymes. But in Thursday's issue of the journal Nature, microbiologists Stephen Kowalczykowski and Piero Bianco report that RecBC has the longest stride yet seen. It is an enzymatic Paul Bunyan, striding ahead 23 rungs every advance.

That kind of workout burns a lot of fuel, and the new finding will require researchers to think differently about how such enzymes use cellular energy sources.

The researchers also found that RecBC has a unique gait. Its front end completes its 23-rung advance, anchors itself to the DNA, and then pulls its back end forward, separating the DNA behind it in a plowlike fashion. Because of this novel mechanism, the researchers dubbed RecBC the "quantum inchworm."

"Overall, understanding this protein will further our understanding of how to maintain chromosomes and to correct genetic defects," said Kowalczykowski. On a smaller scale, literally, the new findings may help engineers who are trying to build nanomachines for jobs such as delivering new genes to DNA or drugs to specific genetic targets in cancer cells, he said.
-end-
The research was supported by a grant from the National Institutes of Health.

Media contacts: Stephen Kowalczykowski, Microbiology, (530) 752-5938, sckowalczykowski@ucdavis.edu;
Piero Bianco, Microbiology, (530) 752-9027, prbianco@ucdavis.edu;
Sylvia Wright, News Service, (530) 752- 7704, ,swright@ucdavis.edu.

University of California - Davis

Related DNA Articles from Brightsurf:

A new twist on DNA origami
A team* of scientists from ASU and Shanghai Jiao Tong University (SJTU) led by Hao Yan, ASU's Milton Glick Professor in the School of Molecular Sciences, and director of the ASU Biodesign Institute's Center for Molecular Design and Biomimetics, has just announced the creation of a new type of meta-DNA structures that will open up the fields of optoelectronics (including information storage and encryption) as well as synthetic biology.

Solving a DNA mystery
''A watched pot never boils,'' as the saying goes, but that was not the case for UC Santa Barbara researchers watching a ''pot'' of liquids formed from DNA.

Junk DNA might be really, really useful for biocomputing
When you don't understand how things work, it's not unusual to think of them as just plain old junk.

Designing DNA from scratch: Engineering the functions of micrometer-sized DNA droplets
Scientists at Tokyo Institute of Technology (Tokyo Tech) have constructed ''DNA droplets'' comprising designed DNA nanostructures.

Does DNA in the water tell us how many fish are there?
Researchers have developed a new non-invasive method to count individual fish by measuring the concentration of environmental DNA in the water, which could be applied for quantitative monitoring of aquatic ecosystems.

Zigzag DNA
How the cell organizes DNA into tightly packed chromosomes. Nature publication by Delft University of Technology and EMBL Heidelberg.

Scientists now know what DNA's chaperone looks like
Researchers have discovered the structure of the FACT protein -- a mysterious protein central to the functioning of DNA.

DNA is like everything else: it's not what you have, but how you use it
A new paradigm for reading out genetic information in DNA is described by Dr.

A new spin on DNA
For decades, researchers have chased ways to study biological machines.

From face to DNA: New method aims to improve match between DNA sample and face database
Predicting what someone's face looks like based on a DNA sample remains a hard nut to crack for science.

Read More: DNA News and DNA Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.