Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: SATURDAY, November 20, 1993 TAG: 9311200076
SECTION: NATIONAL/INTERNATIONAL PAGE: A-5 EDITION: METRO
SOURCE: Seattle Times
DATELINE: SEATTLE LENGTH: Medium
The new understanding of how life works was called "an exceptionally beautiful and interesting story" by Harvard biologist Richard Losick, who wrote an essay on the implications of the work in Friday's issue of the journal Science.
"We're very excited," said Kelly Hughes, the team leader.
His graduate students are going on to determine whether the mechanism could someday be used to get bacteria to produce useful proteins or antibodies for drugs.
Genes represent the blueprints that tell an organism's cells how to develop. Scientists have known for some time that genes switch on and off to give instructions.
For example, genes controlling growth eventually will switch off in a human's teen years, while genes controlling sexual development will switch on.
Learning how to turn genes on and off is one of the Holy Grails of microbiology because it would provide strategies to combat disease or genetic defects.
The Hughes team discovered that not only do genes control an organism's development, but the organism also can control the influence of the genes.
The evidence came in work with salmonella bacteria, part of the E. coli family.
The bacteria build rotating tails called flagella that work like propellers. How do the primitive organisms know when to start and stop building their tails?
Hughes learned the bacteria produce a regulatory protein called FlgM, which suppresses the gene that carries the instructions to build the tails.
When the salmonellae grow the "basal body hooks" their tails will attach to, however, that provides holes in the bacteria and exits for the FlgM protein. The protein leaves the bacteria, lifting the suppression of the gene and letting it direct construction.
As the flagella lengthen, FlgM continues to leak down the interior of the tails, allowing their continued growth. But once the gene orders the tails' final cap, the FlgM can't escape and again accumulates and suppresses the gene from further building.
The discovery that FlgM can be temporarily excreted, Hughes explained, opens the possibility that proteins or antibodies that humans want could also be made and excreted - an example of how this kind of basic discovery might have a practical application.
by CNB