Different evolutionary paths lead plants and animals to the same crossroads

Jan 31, 2011
Despite their divergent evolutionary history, membrane-bound kinase receptors in animals and plants rely on similar regulatory mechanisms to control their activity. Credit: Image: Courtesy of Yvon Jaillard, Michael Hothorn and Jamie Simon, Salk Institute for Biological Studies

In analyzing the molecular sensor for the plant growth hormone brassinolide, researchers at the Salk Institute for Biological Studies discovered that although plants took an evolutionary path different from their animal cousins, they arrived at similar solutions to a common problem: How to reliably receive and process incoming signals.

The team's findings, published in the February 1, 2011 issue of , revealed that so-called tyrosine phosphorylation—used as an "on" or "off" switch and long thought to be a feature unique to animal cells—is a mechanism conserved across the animal and plant kingdoms.

"There seem to be only so many ways to build a robust signaling system," says Howard Hughes Medical Institute investigator Joanne Chory, Ph.D., professor and director of the Plant Molecular and Cellular Biology Laboratory and holder of the Howard H. and Maryam R. Newman Chair, "and and animals have hit upon the same mechanisms."

As different as they may seem, both mammalian and plant cells need to be able to perceive small molecule hormones to respond to changes in the environment. While human cells draw on a wide variety of sensor molecules, including more than 800 different G-protein-coupled , 48 known nuclear hormone receptors and 72 receptor kinases, plants rely mostly on the latter.

"This group of receptors is by far the largest one in plants," says postdoctoral researcher and co-first author Michael Hothorn, "but we don't know much about the activation mechanism apart from 'there's a bunch of new phosphorylations.'"

Kinases transfer phosphate groups to proteins and come in two principal flavors: They either attach the phosphate group to the amino acid tyrosine within the protein or to serine or threonine. The vast majority of receptor kinases in animals possess tyrosine kinase activity, while only a few are specific for serine-threonine.

With the exception of a small handful of dual-specificity kinases, all plant receptor kinases have been pegged as serine-threonine kinases. One of few known outliers is the receptor for brassinolide, a key element of plants' response to light. "Binding of brassinolide to its receptor allows plants to adjust growth when they need to outcompete their neighbors to reach more light or water," explains postdoctoral researcher and co-first author Yvon Jaillais. "But at the same time the receptor needs to be tightly regulated so plants don't waste their resources when they don't have to."

The brassinolide receptor BRI1 is kept in a relatively inactive state by its intracellular tail and a small inhibitory protein known as BKI1. Based on earlier studies in Chory's lab, the Salk researchers knew that autophosphorylation of the receptor was necessary, but what triggered the release of the inhibitory protein remained unclear.

In an effort to understand the activation mechanism, the Salk researchers discovered that BKI1 acts through two evolutionarily conserved motifs: a 20-amino- acid sequence that binds the receptor kinase domain and a lysine-arginine-rich motif that anchors the inhibitory peptide to the plasma membrane. Phosphorylation of a key tyrosine within the membrane-targeting motif releases BKI1 from the membrane, relieving kinase inhibition and allowing the formation of an active signaling complex.

The phosphorylation of BKI1 is not only the first documented example of tyrosine transphosphorylation in plants, the underlying principle also closely resembles the mechanism used by bona fide receptor tyrosine kinases to regulate their activity. "Plant and animal receptor kinases evolved independently, yet their activation relies on similar mechanisms," says Chory.

By defining common features in plant and animal receptor signaling pathways, the Salk researchers hope to learn more about what the requirements for a robust signaling system are. Although plants don't encode canonical tyrosine kinases in their genomes, tyrosine phosphorylation will emerge as an important topic in plant signaling, predicts Hothorn.

Explore further: How a molecular Superman protects the genome from damage

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User comments : 14

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nuge
5 / 5 (4) Jan 31, 2011
So evolution can bring organisms to the same form along different paths? Awesome, that explains star trek races.
GaryB
1 / 5 (1) Feb 01, 2011
The convergence of Star Trek races was in fact brought about by evolution, just not in the way you're thinking. It was brought about by playing off of certain human propensities.

kevinrtrs
1 / 5 (11) Feb 01, 2011
Plants are essential for animal life on earth, hence it should not be surprising that they produce that which is required for animal life. If they didn't and were just random unrelated developments of their own, no animals or humans would survive.
Evolutionists have a really big, big, BIG headache with plants. There is no clear evidence of ANY kind of evolutionary development. Most of the fossils dated in their billions of years look exactly like the stuff that exists today. There's no easily expressed method to classify or build an evolutionary tree. Right now there's multiple suggestions and lots of arguments about what is related to what or what preceded what. The word "conserved" gives away the nonsense that is evolutionary thought: It basically means "we're stumped that there should even be a hint of commonality between X and Y".

It makes so much more sense from a biblical perspective that all animal and human life was given plants to eat in the beginning by a common designer.
kevinrtrs
1 / 5 (6) Feb 01, 2011
Just as a aside, the [image of the] kinase receptor seems like quite a happy chappy jumping jack having fun and enjoying itself!
Mayor__Dooley
4.2 / 5 (5) Feb 01, 2011
The only mystery of the evolutionary tree is where Kevin the Troll fits.
LivaN
5 / 5 (3) Feb 01, 2011

It makes so much more sense from a biblical perspective that all animal and human life was given plants to eat in the beginning by a common designer.


Why yes, that makes perfect sense!

Everything just suddenly existed because of the whim of some sort of being that existed...before everything existed? Wait I'm confused now. Did this entity exist before it made everything exist, or does it exist because it made everything exist?
PaulieMac
5 / 5 (7) Feb 01, 2011
Evolutionists have a really big, big, BIG headache with plants. There is no clear evidence of ANY kind of evolutionary development. Most of the fossils dated in their billions of years look exactly like the stuff that exists today.


Utter rubbish. You, literally, just made that up, obviously.

For anyone interested in the evolution of plants, I'd suggest the wiki article "Plant_Evolution" as a decent starter, with the references as further light reading.

Right now there's multiple suggestions and lots of arguments about what is related to what or what preceded what.


Also known as 'scientific debate'.
PaulieMac
5 / 5 (7) Feb 01, 2011
Plants are essential for animal life on earth, hence it should not be surprising that they produce that which is required for animal life. If they didn't and were just random unrelated developments of their own, no animals or humans would survive


Oh, what a tangled web we weave, when first we practice to deceive, eh Kevin?

Animals have evolved to eat what's available. Of *course* they have. As always you stress the "random" element of evolution - which is to say, mutation - but fail to account for selection. Which is not random.

Mutation + selection = evolution. Pretty simple stuff. No magical sky fairy required. And I must say - you do your cause no favours with your flimsy attempts. What you think to achieve with your dishonest posts, so lacking in logic is beyond me. Perhaps I should say: 'god only knows' ;-) lol
Skultch
5 / 5 (4) Feb 01, 2011
Ahhhh, Kevin. You crazy guy, you. :) Another drive-by coward move?

What motivates such a strange bird?
Ethelred
5 / 5 (3) Feb 02, 2011
Evolutionists have a really big, big, BIG headache with plants
No. Plants were one way that Darwin studied evolution. Plants were where we learned genes which fixed Darwin's problem where he thought inheritance is blended which was a problem for his theory.
here is no clear evidence of ANY kind of evolutionary development
Sure there is. Just not as much as for animals since plants don't have bones or teeth that hold up better over time. Plus there are simply less people interested in studying plants. Plants are boring.
Most of the fossils dated in their billions of years look exactly like the stuff that exists today
Yes. Those fossils you think don't exist since they came from more than 10,000 years ago have the exact same features on the same scale. They have a mostly spherical shape on the outside. Lots and lots of detail there. An outside and nothing else. Just enough to know they existed and thus annoy YECs to no end so they have engage in mendacity like that.

More
Ethelred
5 / 5 (2) Feb 02, 2011
There's no easily expressed method to classify or build an evolutionary tree.
Sure there is. Round phylum for everything untill there was some oxygen around.
The word "conserved" gives away the nonsense
Conservatives do spout a lot nonsense so I am not surprised that someone as ignorant as you would assume the word conserved implies nonsense.
"we're stumped that there should even be a hint of commonality between X and Y".
Oh horse manure. I am not stumped and doubt anyone else is. Well YOU are stumped by my question.

When was the Flood Kevin?
It makes so much more sense from a biblical perspective that all animal and human life was given plants to eat in the beginning by a common designer.
Except that the Earth is vastly more than 10,000 years old, the designer needs a designer, the flood never happened and we have megatons of evidence for evolution.

If the Flood happened why can't you tell us when it did, Kevin?

Ethelred
Moebius
1 / 5 (1) Feb 05, 2011
If I recall correctly, the different humanoid races in Star Trek are related, no convergent evolution necessary. Divergent if anything.
antialias
not rated yet Feb 06, 2011
The only mystery of the evolutionary tree is where Kevin the Troll fits.

Random mutation. They usually don't breed.
Pesto
not rated yet Mar 03, 2011
Plants are cool and not boring as pointed out by Etherlred. We cannot exist without plants whereas plants can exist without us! Plants are great adapters and we have a lots to learn from them. my two cents!