Biological complexity:one enzyme two hormones (Introduction)

by David Turell , Wednesday, November 23, 2016, 22:23 (2703 days ago) @ David Turell

Tight controls are necessary for all levels of hormones, which are very active biologically. This plant has one enzyme that controls the levels of two plant hormones:

http://phys.org/news/2016-11-enzyme-hormones.html

"the research team of Joseph Jez, professor of biology in Arts & Sciences and a Howard Hughes Medical Institute Professor, reports that the enzyme GH3.5 can control the levels of two plant hormones, auxin and salicylic acid. It is the first enzyme of its kind known to control completely different classes of hormones.

"Auxin controls a range of responses in the plant, including cell and tissue growth and normal development. Salicylic acid, on the other hand, helps plants respond to infections, which often take resources away from growth. Plants must tightly control the levels of auxin and salicylic acid to properly grow and react to new threats.

"'Plants control hormone levels through a combination of making, breaking, modifying and transporting them," said Corey Westfall, a former graduate student who led this Jez lab work along with current graduate student Ashley Sherp.

"By stitching an amino acid to a hormone, GH3.5 takes the hormones out of circulation, reducing their effect in the plant.

***

"The scientists were expecting to find key differences between GH3.5 and related proteins that would account for its unique ability to modify multiple hormones.
To their surprise, the part of the enzyme that binds and modifies hormones looked almost identical to related enzymes that can only modify auxin. The surprising similarities between the multi-purpose GH3.5 and its single-use relatives suggests that unrecognized elements of these proteins influence which molecules they can bind and transform.

"'These surprising results mean there's something going on that we're not seeing in the sequence or the structure of these enzymes," Jez said.

"Solving this mystery could tell us more about how enzymes distinguish among similar molecules, a discriminatory ability that is critical for all life, including people as well as plants."

Comment: Enzymes are the workhorses of biological chemistry. They cause reactions to happen quickly. The molecules are giant and very specific in form in order to do their job. How does evolved life find them in a landscape of possible forms?