University Of Texas Southwestern Medical Center At Dallas Researchers Identify Key Photoreceptor In Fungi

[Guest guest]

http://www.sciencedaily.com/releases/2002/07/020705090349.htm

Source: University Of Texas Southwestern Medical Center At Dallas

(http://www.swmed.edu/)

Date: Posted 7/5/2002

UT Southwestern Researchers Identify Key Photoreceptor In Fungi

DALLAS - July 4, 2002 - After 40 years of searching for the photoreceptor

that controls multiple vital processes in fungi, researchers at UT

Southwestern Medical Center at Dallas have discovered the protein that

triggers this phenomenon.

Light regulates several physiological processes in fungi, including their

ability to produce spores and the synchronization of their internal

biological clocks, but their photoreceptors - receptors that are sensitive

to light and are essential for most ongoing processes - were not known until

this breakthrough discovery made by UT Southwestern researchers.

In this week's on-line version of Science, the researchers report that the

protein White Collar -1, or WC-1, is the photoreceptor for light responses

in fungi, which encompass yeast and mold. Fungi share with bacteria the

important ability to break down complex organic substances of almost every

type and are essential to the recycling of carbon and other elements in the

cycle of life. Fungi are also important as foods and to the fermentation

process in the development of substances for industrial and medical

importance, including alcohol, antibiotics, other drugs and antitoxins.

UT Southwestern researchers also specifically identified WC-1's role in the

internal biological clock of fungi, which is called the circadian clock and

is controlled by light. This internal time-keeping system is a fundamental

property in almost all organisms, allowing them to adapt to the natural

environment.

" This discovery is important because it provides a better understanding of

how life works and how life adjusts to the environment, " said Dr. Yi Liu,

senior author of the study and an assistant professor of physiology at UT

Southwestern.

WC-1 previously had been identified as a protein involved in the transfer of

genetic code information, a process called transcription, but researchers

had not discovered its role as a photoreceptor until now.

" We hypothesized if the photo sensory domain of WC-1 was removed, all light-

regulated processes, including the circadian clock, would be blind, " said

Liu.

The researchers tested this hypothesis by creating an organism that lacked

WC-1 putative photo sensory domain. Liu and his collaborators demonstrated

that WC-1, like all known photoreceptors, is associated with a photo

pigment, the molecule that is sensitive to light.

" As we predicted, this mutant organism was literally blind to light. The

circadian clock was no longer synchronized by light and the light-regulated

genes were not turned on after light treatment, which affected many

physiological processes, " Liu said.

" All light responses were interrupted in this mutant, including the growth

of mold and the production of spores, " said Liu, who also was co-author of a

second study published on this week's Science Web site about the role of

WC-1 in mediating light input to the circadian clock.

Other researchers involved in the UT Southwestern study included Drs. Ping

Cheng and Qiyang He, both first authors of the study and postdoctoral

researchers in physiology; Dr. Gardner, assistant professor of

biochemistry; Lixing Wang, a research technician in physiology; and Dr.

Yuhong Yang, a postdoctoral researcher in physiology.

The study was supported by grants from the National Institutes of Health.

Note: This story has been adapted from a news release issued by University

Of Texas Southwestern Medical Center At Dallas for journalists and other

members of the public. If you wish to quote from any part of this story,

please credit University Of Texas Southwestern Medical Center At Dallas as

the original source. You may also wish to include the following link in any

citation:

http://www.sciencedaily.com/releases/2002/07/020705090349.htm